.Net homepage

ASP.NET:Email Web Page

The code is very simple.allow to email the contents of a web page The page, with codebehind, is listed below:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="SendWebPageWithEmail.aspx.cs"
Inherits="Samples_SendWebPageWithEmail" %> 
<!DOCTYPE html public "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">   
<form ID="Form2" runat="server" method="post">
<table align="center" border="1">         
<tr><td colspan="2"><span ID="lblTitle">ASP.NET Email Web Page</span></td> </tr>
<tr><td>URL:</td></td><asp:textbox ID="txtURL" runat="server" Width="362px"></asp:textbox>
</tr><tr><td> To Email:</td>
<td  style="width: 158px"><asp:textbox ID="txtTo" runat="server" Width="362px"></asp:textbox>
</td></tr><tr><td>From Email:</td><td style="width: 158px">
 <asp:textbox ID="txtFrom" runat="server" Width="362px"></asp:textbox>
</td></tr><tr><td>Email Subject:</td><td  style="width: 158px">
<asp:textbox ID="txtSubject" runat="server" Width="362px"></asp:textbox>
</td></tr><tr><td><asp:button ID="btn_Send" runat="server" OnClick="btn_Send_Click" Text="Send" /></td>
<td  style="width: 158px"><asp:literal ID="ltr_sent" runat="server"></asp:literal>
<asp:label ID="lbl_Result" runat="server"></asp:label>
</td></tr>         
</table></form></html>

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Net;
using System.IO;

public partial class Samples_SendWebPageWithEmail : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
 private String readWebPage( string url)
{
String result;
WebResponse objResponse;
WebRequest objRequest = System.Net.HttpWebRequest.Create(url);
objResponse = objRequest.GetResponse();
using (StreamReader sr =new StreamReader(objResponse.GetResponseStream()))
{
result = sr.ReadToEnd();
 // Close and clean up the StreamReader
sr.Close();
}
return result;
}
protected void btn_Send_Click(object sender, EventArgs e)
{
String message = readWebPage(txtURL.Text);
if (Page.IsValid)
{
try
{
MailMessage EmailMsg = new MailMessage();
 //'Set the properties
EmailMsg.To.Add(txtTo.Text);
EmailMsg.From = new MailAddress(txtFrom.Text);
 //'If you want to CC this email to someone else //EmailMsg.CC.Add(CcM);
    //'Send the email in text format
EmailMsg.IsBodyHtml = true;
EmailMsg.Priority = MailPriority.Normal;
EmailMsg.Subject = txtSubject.Text;
EmailMsg.Body = message;//"webpage content?";
EmailMsg.IsBodyHtml = true; SmtpClient SMTPServer = new SmtpClient("MailServerName");
SMTPServer.UseDefaultCredentials = false;
System.Net.NetworkCredential SMTPUserInfo = new System.Net.NetworkCredential("Username","Password");
SMTPServer.Credentials = SMTPUserInfo;
SMTPServer.Send(EmailMsg);
lbl_Result.Text = "Page successfully  sent!";
ltr_Sent.Text = message;
}
catch (Exception ex)
{
lbl_Result.Text = "An error occurred: "  + ex.ToString();
}}}

Asp.Net Multiple File Upload...

The HtmlInputFile and the FileUpload controls allow the user to upload files to the server. FileUpload is a 2.0 addition server control that has most of the same features of the HtmlInputFile control, but with a few added properties. However, it would be easier to have a control that allows the user to upload more than one file at a time, or to allow the user to add a specific number of input file boxes dynamically in the form. Before we begin, you should be aware of some limitations. These controls do not store their viewstate; they implement the methods of IPostBackDataHandler; however, the LoadPostData method always returns false. Even overriding these methods yields no effect, as the value property for the file upload is read-only. I’ve done some research, and supposedly in newer browsers this could be set, but I have not come across a solution to do so. If you read my article on the Collapsible Panel, you will have seen this event notation, where each event has an ING and an ED event, one firing before the action takes place (while also allowing you to cancel it), and one that fires afterward. This is the structure for events to add and clear input boxes in the control. The control also implements IRepeatInfoUser, to render the file upload boxes in a horizontal or vertical fashion, or creating a table structure. This just adds to the versatility of the control, even though in most situations, it won’t be desired. In the rendering process, I render Add and Clear links using the header or footer sections of the render item. To determine this, the HasHeader and HasFooter methods of IRepeatInfoUser check the LinkLocation property enumeration.

public ReadOnly Property HasFooter() As Boolean Implements System.Web.UI.WebControls.IRepeatInfoUser.HasFooter 
  Get Return (Me.LinkLocation = LinkLocationType.Bottom)
End Get End Property
<Browsable(False)>public ReadOnly Property HasHeader() As Boolean Implements 
System.Web.UI.WebControls.IRepeatInfoUser.HasHeader 
Get Return (Me.LinkLocation = LinkLocationType.Top)
End Get End Property
<Browsable(False)>
public Sub RenderItem(ByVal itemType As System.Web.UI.WebControls.ListItemType,
 ByVal repeatIndex As Integer,
_ByVal repeatInfo As System.Web.UI.WebControls.RepeatInfo, 
_ByVal writer As System.Web.UI.HtmlTextWriter) 
Implements System.Web.UI.WebControls.IRepeatInfoUser.RenderItem writer.RenderBeginTag(HtmlTextWriterTag.Tr)
writer.RenderBeginTag(HtmlTextWriterTag.Td)
If (itemType = ListItemType.Header OrElse itemType = ListItemType.Footer) Then
 writer.AddAttribute(HtmlTextWriterAttribute.Href,
 "javascript:" & Page.ClientScript.GetPostBackEventReference(Me, "add"))
writer.RenderBeginTag(HtmlTextWriterTag.A)
writer.Write(Me.AddLinkText)
writer.RenderEndTag()
writer.Write(" ")
writer.AddAttribute(HtmlTextWriterAttribute.Href, "javascript:" & 
Page.ClientScript.GetPostBackEventReference(Me, "clear"))
writer.RenderBeginTag(HtmlTextWriterTag.A)
writer.Write(Me.ClearLinkText)
writer.RenderEndTag()
ElseIf (itemType = ListItemType.Item OrElse itemType = ListItemType.AlternatingItem) Then
Me.Controls(repeatIndex).RenderControl(writer)
End If writer.RenderEndTag() '/td
writer.RenderEndTag() '/tr
End Sub

The fileupload controls are created in CreateChildControls and rendered above as the item. The file boxes are based upon the
InputBoxes property, which is an integer value, stating how many input boxes to use for the control. This value is added or
reset through the AddNew and Clear methods, which AddNew adds one to it everytime, and Clear resets it back to one.

Protected Overrides Sub CreateChildControls()
For intI As Integer = 1 To Me.InputBoxes
Dim objBox As New FileUpload
objBox.ID = "fu" & intI
Me.Controls.Add(objBox)
Next End Sub

This control also makes use of the method GetPostBackEventReference in the RenderItem method. This method returns
a javascript string with the function that will perform the posting back (which is rendered in a link’s href property).
The references are shown below; we use two event arguments for this control: add and clear. RaisePostBackEvent handles
the postback. It receives the event argument, and calls the appropriate method. 'In RenderItem method, rendered in the HREF property of an

Page.ClientScript.GetPostBackEventReference(Me, "add")
Page.ClientScript.GetPostBackEventReference(Me, "clear")
public Sub RaisePostBackEvent(ByVal eventArgument As String) 
Implements System.Web.UI.IPostBackEventHandler.RaisePostBackEvent
Dim strArg As String = eventArgument.ToLower()
If (strArg = "add" OrElse strArg = "addnew") Then
AddNew()
ElseIf (strArg = "clear") Then Clear()
End If End Sub

This control also makes use of IPostBackDataHandler and uses the LoadPostData method to check any possible uploaded files,
and if there is one, raise an event. This allows the developer to handle the uploading of the file. As an alternative,
this control could
handle that action through an automated means by using an UploadFolder property, referencing a folder on the web server.

public Function LoadPostData(ByVal postDataKey As String, ByVal postCollection As 
_System.Collections.Specialized.NameValueCollection) As Boolean Implements_
 System.Web.UI.IPostBackDataHandler.LoadPostData Me.EnsureChildControls()
For Each objControl As Control In Me.Controls
If (TypeOf (objControl) Is FileUpload) Then

Dim objUpload As FileUpload = CType(objControl, FileUpload)
If (objUpload.HasFile) Then OnInputBoxPosted(New PostedFileEventArgs(objUpload.PostedFile))
End If 
End If 
Next 
End Function

For the control to receive postbacks, you have to call Page.RegisterRequiresPostBack method. This will then allow LoadPostData to fire.

protected Overrides Sub OnPreRender(ByVale As System.EventArgs)
MyBase.OnPreRender(e)
If (Page IsNot Nothing) Then Page.RegisterRequiresPostBack(Me)
End If
End Sub

This control works well with allowing users to upload multiple files. If using the links (add and clear), you may want to list a disclaimer stating that the user should add the desired number of textboxes first before browsing to all of the files, as they won’t be saved. Also, the control allows you to upload the files through a button of your own. If you don’t want the add/clear links shown, set the LinkLocation property to the None enumeration, and they will disappear. This class comes with a PostedFileEventArgs that contains details about the posted file, which is made available to the user in the InputBoxPosted event. It is defined below.

public Class PostedFileEventArgs
Inherits System.EventArgs

Private m_objFile As HttpPostedFile

public ReadOnly Property FileName() As String
Get
Return m_objFile.FileName
End Get
End Property <Browsable(False)>
Public ReadOnly Property FileStream() As Stream
Get
Return m_objFile.InputStream
End Get
End Property
<Browsable(False)>
Public Sub New(ByVal objFile As HttpPostedFile)
m_objFile = objFile
End Sub
public Sub SaveAs(ByVal strFilePath As String)
m_objFile.SaveAs(strFilePath)
End Sub
End Class

When the test page runs, test the links for adding/clearing. Also, try setting the InputBoxes property, and play around with the IRepeatInfoUser
properties to change the
layout. Lastly, when you upload files, it will render the name of the file in the page.

How to respond with code 404 (Not Found) in ASP.NET

Suppose you configured custom 404 page in web.config file in the customErrors section. So whenever user requests non-existent aspx page,
ASP.NET run-time returns well formatted message to the user. Also you have a page that shows articles from a database according to
article ID passed in the url (for example: article.aspx?id=1). But if user passes article ID that doesn't exists the page must return code
404 (Not Found) and show the custom 404 page like in the previous situation. Fortunately you don't need to parse the customErrors
section to get name of the custom 404 page. Just throw

HttpException: new HttpException(404, "Article not found");
ASP.NET run-time will catch the exception and will redirect to the custom 404.

Code snippets for some common operations with exceptions

Download and install these additional code snippets for common operations with exceptions. To use them type shortcut for the code
snippet that you want to add to your code and then type Tab, Tab to invoke it.

thr - throw new
thrni - throw new NotImplementedException("");

Send an e-mail any time an unhandled exception occurs

Consider using built-in ASP.NET health monitoring to monitor your website. Especially if you are not monitoring it at all yet.
ASP.NET health monitoring contains ready-to-use Web health-monitoring events classes (Web events) and health-monitoring
providers (listeners). For example, you can easily configure it to send an email any time an error is detected.

Turn off Session State if you're not using it

Since ASP.NETSession State is on by default, you pay the cost in memory even if you don't use it. If you're not using Session State,
turn it off and save yourself the overhead. There are several ways to do this:
1.If you're not using SessionState at all, turn it off completely via web.config file:

<system.web>
<sessionState mode="Off"></sessionState>
2.If you're using SessionState,
    but it's required only for a few pages, then first turn
    it off for all pages:
<system.web>
<pages 
enableSessionState="false">
 then enable it for a specific page:
<%@
Page ... EnableSessionState="true"
%>
P.S. obviously such optimization makes sense only for high-traffic web
    sites.

How to debug Windows Service startup

Actually you can use this trick every time when:
1.You want to debug a process startup.
2.You can't run the process by hitting F5 in Visual Studio (for example, Windows Service).
So the problem is that you can't simply attach the Visual Studio debugger to the process as there isn't one to attach to until after you start the process. However, once you start the process if you have a bug such as an exception in the process's initialization you won't get the debugger attached to the process before it's too late.
Calling
Debugger.Launch() or Debugger.Break()
in your code allow you to debug such problems. This methods pop up the following screen asking you which instance of the debugger it should use to debug the application.

How to change HTML markup produced by ASP.NET controls

There are at least two ways of changing HTML markup produced by standard ASP.NET controls. The most obvious one is to derive a new class based on an existing ASP.NET control class and override the necessary rendering methods. Another option that is worth considering is to write a small control adapter for the existing ASP.NET control. This is a little chunk of logic that you add to your web site to effectively "adapt" an ASP.NET control to render the HTML you prefer. This approach has the following two major advantages over custom controls:
1.You don't need to add the @Register directives to your pages.
2.The ASP.NET framework comes with a built-in means to apply the adapters to just certain browsers. When you build entirely new custom controls you have to write your own logic to handle browser detection to vary the response.
For example you can use
ASP.NET 2.0 CSS Friendly Control Adapters package to generate CSS friendly markup from some of the more commonly used ASP.NET controls.

Label to a form input field

If you set a label to a form element set the AssociatedControlID property. This will force the label to render as
<label> rather than <span>.
A benefit of using the AssociatedControlID property is that clicking a label when this property is set automatically changes the form focus to the associated form input.

Add Windows Explorer to your Visual Studio tools menu

I often need to open Windows Explorer and browse to the current file, folder, or project that I am working on in Visual Studio.
This tip allows you to achieve this by clicking "Windows Explorer" in the Tools menu, and is one of the most simple-yet-useful tips I know of.
To set it up, click Tools, then External Tools..., then click Add. Now enter the following data:
Title: Windows Explorer
Command: explorer.exe
Arguments: /select,"$(ItemPath)"
Leave Initial directoy blank, and click OK.
Now when you click Tools, Windows Explorer, Windows Explorer will open with the current file you are editing selected.

Correct event invocation

Be aware that if there are no subscribers a .NET event will be null. Therefore when raising the event from C# test it for null first.

public event EventHandler
                    SelectedNodeChanged;
protected 
    virtual void OnSelectedNodeChanged(object sender, EventArgs e)
{//Event will be null if there are no subscribers

if
                    (SelectedNodeChanged != null)
{
SelectedNodeChanged(this,e);} }

However in multithreaded application the last subscriber can unsubscribe immediately after the null check and before the event is raised. To avoid a null reference exception make a temporary copy of the event.

public event EventHandler SelectedNodeChanged;
protected virtual void OnSelectedNodeChanged(object sender, EventArgs e)
{
//Make a temporary copy of the event to avoid possibility of 
//a race condition if the last subscriber unsubscribes   
//immediately after the null check and before the event is raised. 
EventHandler handler = SelectedNodeChanged;
//Event will be null if there are no subscribers
if(handler != null)
{handler(this,e);} }

How to view code that is covered by the IntelliSense pop-up

When working in Visual Studio 2008 and the IntelliSense pop-up is visible, but you would like to view the code that is covered by it, press and hold the Ctrl key, and the pop-up becomes transparent so that you can view the code that is below the pop-up.

When returning DataReader from a function, specify CommandBehavior.CloseConnection

When you create an ADO.NET DataReader object, specify the CommandBehavior.CloseConnection enumeration in your call to ExecuteReader. This ensures that when you close the DataReader, the SQL connection is also closed. This is especially helpful when you return a DataReader from a function, and you do not have control over the calling code. If the caller forgets to close the connection but closes the reader, both are closed when the DataReader is created by using CommandBehavior.CloseConnection.
This is shown in the following code fragment.

public SqlDataReader CustomerRead(int CustomerID){
//... create connection and command, open connection
return myCommand.ExecuteReader(CommandBehavior.CloseConnection);
}
//... client code
SqlDataReader myReader = CustomerRead(10248);
//... read some data
myReader.Close(); 
// reader and connection  are closed

Use explicit casting instead of DataBinder.Eval

The DataBinder.Eval method uses .NET reflection to evaluate the arguments that are passed in and to return the results. Consider limiting the use of DataBinder.Eval during data binding operations in order to improve ASP.NET page performance. Consider the following ItemTemplate element within a Repeater control using DataBinder.Eval:

<ItemTemplate>
<tr><td><%#DataBinder.Eval(Container.DataItem,
            "field1") %></td>
<td><%#DataBinder.Eval(Container.DataItem,
        "field2") %></td></tr></ItemTemplate>

Using explicit casting offers better performance by avoiding the cost of .NET reflection. Cast the Container.DataItem as a DataRowView:

<ItemTemplate><tr>
<td><%# ((DataRowView)Container.DataItem)["field1"] %></td>
<td><%# ((DataRowView)Container.DataItem)["field2"] %></td>
</tr>
</ItemTemplate>

Consider using weak references for your custom caching solutions

Consider using weak references when you implement a custom caching solution, so that cached objects can be released by garbage collection when there is memory pressure. You should use weak references mostly for objects that are not small in size because the weak referencing itself involves some overhead. They are suitable for medium to large-sized objects stored in a collection.

Automatically insert attribute value quotes

Visual Studio HTML/ASPX editor can save you some time if you enable option
Tools | Options... | Text Editor | HTML | Format | Insert attribute value quotes when typing.
When this option is enabled, once you type a name of an attribute and following "=" symbol, Visual Studio automatically inserts a pair of quotes and invokes IntelliSense menu. After that you need only to select an attribute value from the menu and hit the Enter button. It's another nice timesaver.

Correct using of ASP.NET Cache

Often in ASP.NET application we see a code which looks like this one:

 if (Cache["SomeData"]!=null)
 {  string name = ((SomeClass)Cache["SomeData"]).Name;}

This code is not safe enough and the second statement can generate a NullReferenceException sometimes. There is no guaranttee that a cached object will stay in the cache between two calls. After the first call it can be deleted either by garbage collector or by another thread to refresh cached data. So to overcome this problem rewrite the code using as operator:

SomeClass< someClass = Cache["SomeData"] as SomeClass;
if (someClass != null)
          {
string name = someClass.Name;
//.....
}

How to create fully qualified URLs

With ASP.NET it's quite easy to get absolute path to a page by calling the VirtualPathUtility.ToAbsolute method. Getting absolute URL is not that obvious but still quite easy. Just combine request url with absolute path to your ASP.NET page:

string absolutePath = VirtualPathUtility.ToAbsolute("~/test/MyWebForm.aspx");
Uri newUri = new Uri(Request.Url, absolutePath);

COALESCE function instead of long CASE WHEN ... ELSE (T-SQL)

Instead of using long "

SELECT ... 
CASE WHEN ... ELSE ..."

construction, you can use the COALESCE function when you need to find a value that is not NULL. Lets review the following T-SQL expression,

in which we need to select an available "source":

SELECT TheSource =
CASE
WHEN localSource IS NOT NULL THEN
       
        localSource
WHEN intranetSource
IS NOT NULL THEN
   
    intranetSource
WHEN internetSource
IS NOT NULL THEN
   
    internetSource
ELSE 
   
    '' END
FROM ...
Now lets rewrite the code above using COALESCE function:
SELECT TheSource =COALESCE(localSource,intranetSource, internetSource, '')
FROM ...

The tip applies to MS SQL Server 2000/2005.

Cut a line into memory

While in Visual Studio.NET source code editor, press Ctrl+L to cut a line of code into memory. This is an easy way to move lines around your pages, or delete a set of lines quickly. Simple, yet useful!

How to check email works without using SMTP

Testing code that sends email has always been a pain. You had to set up a SMTP service just to test that your .NET application sends the e-mail correctly. However, there is a way to send e-mails with no SMTP server set up. Just configure your .NET application to drop e-mails into a specified folder instead of sending them via SMTP server:

<system.net> <mailSettings><smtp deliveryMethod="SpecifiedPickupDirectory">
<specifiedPickupDirectory pickupDirectoryLocation="c:\Test\"/> </smtp> </mailSettings>
</system.net>

This will instruct SmtpClient class to generate mail message,
                    save it as .eml file and drop it into c:\emailTest\folder.

What is the difference between UriBuilder.ToString and UriBuilder.Uri.ToString

UriBuilder.ToString - the resulting string always contains Port, even if it is the default port for the Scheme. For example - http://localhost:80/tips.
UriBuilder.Uri.ToString - the resulting string only contains the port if it is not the default port for the scheme. For example - http://localhost/tips.

Therefore, in most of the cases UriBuilder.Uri.ToString should be used to omit redundant port specification.

Visual Studio Bookmarks

Bookmarks can be used to mark places in the code, like the code that you might want to jump back and forward. Bookmarks can be related to task list shortcuts, kind of the same functinality. The bookmarks can be setup very easy, by pressing
Ctrl+K, Ctrl+K to leave bookmark.
For navigation, you can press
Ctrl+K, Ctrl+N to move to the next bookmark,
or Ctrl+K, CTRL+P for the previous bookmark. It's easy, just try it now.

Generating compiler warnings for calls to an obsolete methods

Throughout the product development cycle, occasionally certain methods become obsolete. If you can't modify those methods, will need to write another implementation of the method using a slightly different name or signature. To maintain compatibility, you do not want to remove the old method and break your code. This is where the .NET Obsolete attribute comes in handy:

[Obsolete("Use the new LogRequestEx instead.")]
public static void LogRequest(string feedUrl, string referer)
{
Setting the Obsolete attribute as above makes a warning message appear in the Visual Studio's Error List stating that the particular call to a method is obsolete. The warning message also includes your personalized message that you pass as the attribute's argument (such as, "Use the new LogRequestEx instead").

Big solutions can be organized using Solution Folders

Here is an example of a big Visual Studio.NET solution that contains numerous projects: Such a big Visual Studio.NET solutions can be organized by grouping related projects into folders. Just right-click on the solution node and choose Add | New Solution Folder to add a Solution Folder. Then just Drag'n'Drop projects into this folder. This also will allow you to do some operations on a group of projects. For example, unload all projects in a Solution Folder, collapse or hide entire Solution Folder so that you can work easily in Solution Explorer in Visual Studio.NET.

How to change the default view for Web pages and WinForms in Visual Studio

By default Visual Studio.NET initially displays Web pages and WinForms in a Design view. But if you prefer Source view, you can set it to be the default view. For Web pages:
1.Go to Tools | Options... | HTML Designer and select Source View.
2.Click OK button. For WinForms: 1.Right-click on a WinForm in the Solution Explorer and then click Open With.... Open With dialog opens. 2.Choose CSharp Editor in the list and then click Set as Default button.
3.Click OK button.

Use DebuggerBrowsable attribute to clean up class view in a debugger

The DebuggerBrowsable attribute determines if and how a field or property is displayed in the debugger variable windows. Let's review the following code example:

public class VehicleSeries{
private 
   
    string _name;
public string Name
{
get { return_name; }
set { _name = value; }
}
private List<string> _vehicles = newList<string>();
public List<string> Vehicles
{
get { return _vehicles; }

set { _vehicles = value; }
} }
The resulting display within the debugger is shown below:
Now lets remove duplicate information and show constituent vehicles
    by adding a few DebuggerBrowsable attributes:

public class VehicleSeries
{
[DebuggerBrowsable(DebuggerBrowsableState.Never)]

private 
   
    string _name;
public string Name
{
get { return_name; }
set { _name = value; }} [DebuggerBrowsable(DebuggerBrowsableState.Never)]
private List<string> _vehicles = newList<string>();
[DebuggerBrowsable(DebuggerBrowsableState.RootHidden)] 
public  List<string> Vehicles { get { 
 return _vehicles; } 
 
  set { _vehicles = value; }
  } }

This results in the following view in the debugger: P.S. Also take a look at a tip "Use DebuggerDisplay attribute for a better debugger experience

What is the difference between URL and URI?

A URL is the address of some resource on the web, which means that normally you type the address into a browser and you get something back. There are other type of resources than web pages, but that's the easiest conceptually. The browser goes out somewhere on the internet and accesses something. A URI is just a unique string that uniquely identifies something, commonly a namespace. Sometimes they look like a URL that you could type into the address bar of your web browser, but it doesn't have to point to any physical resource on the web. URI is the more generic term, and a URL is a particular type of URI in that a URL has to uniquely identify some resource on the web.

Don't generate unnecessary WinForm members for Label controls

To get rid of some auto-generated form level fields that point to a control that will never be referenced (for example, labels, panels, etc.), do the following:
1.In the Windows Forms Designer, select a control.
2.Set GenerateMember property for this control to false.
As a result a member of the form will not be generated for this control. It saves you 4 bytes per member and more importantly removes "clutter" from IntelliSense and any diagrams you auto generate.

Simplify the usability of your generic methods with type parameter inference

When the parameter signature of a generic method includes a parameter that is of the same type as the type parameter for the method, it's not necessary to specify the type parameter when calling the method. Let's review an example:

public class Class1
{
//both method type argument and parameter are of
    the same type public
   
    void SomeGenericMethod<T>(T sameAsTypeParameter)
{
} }
public 
   
    class Test
{
static 
   
    void Main()
{
Class1 obj = new Class1();

//It's not necessary to specify method type parameter
   
    //Instead of obj.SomeGenericMethod<int>(100)
        use
obj.SomeGenericMethod(100);
} }

As you can see in the example above, the syntax for calling generic method is identical to syntax of calling non-generic method. This ability is called generic type inference. To enable inference, the parameter signature of a generic method must include a parameter that is of the same type as the type parameter for the method. Note: the compiler cannot infer the type based on the type of the returned value alone.

Two approaches to update database row if exists, insert if not

The biggest challenge with update/insert (so called upsert) is to minimize any kind of locks. Unfortunately there is no silver bullet for this yet. So let's review two the most commonly used methods:

1. Update, if @@ROWCOUNT = 0 then insert
                   
                    UPDATE Table1 SET
                        Column1 = @newValue WHERE Id = @id
                   
                    IF @@ROWCOUNT = 0 BEGIN
                   
                    INSERT INTO Table1 (Id, Column1) VALUES (@id, @newValue) END

This method is good if you know that in most of the cases a row will exist and update will be performed. Otherwise the second method should be used.

2. If row exists update, otherwise insert
IF EXISTS(SELECT * FROM
       
        Table1 WHERE Id = @id)
BEGIN UPDATE Table1 
   
    SET Column1 = @newValue WHERE
        Id = @id
END
ELSE
BEGIN
INSERT INTO Table1 (Id, Column1) VALUES (@id, @newValue)
END

This one is good if you know that in most of the cases a row will not exist and insert will be performed. For such cases it executes SELECT statement followed by INSERT statement. That results in less expensive lock comparing to UPDATE + INSERT in previous method. P.S. both methods should be used in transaction with isolation level
Serializable.

Improve your code readability: make more sense to conditions

Instead of:
if (!string.IsNullOrEmpty(state) && state.Length == 2)
{
}
do this:
bool stateIsValid =!string.IsNullOrEmpty(state) && state.Length== 2;
if (stateIsValid)
{
}

Speed up inserting records into database with SqlBulkCopy class

When you need to insert a great deal of rows into database (for example, when importing data from a flat file or when importing data from one database into another one), and you need to do it programmatically because it needs to be pre-processed on the fly, then you should use SqlBulkCopy class. The class uses Tabular Data Stream for fast transmitting data from client to a database server (therefore you'll see a bunch of "strange" INSERT BULK statements in a SQL Profiler):

DataTable  dataTable = new DataTable();
using (SqlBulkCopy bulkCopy = new SqlBulkCopy(connection))
{bulkCopy.DestinationTableName = "dbo.DestinationTale";
bulkCopy.WriteToServer(dataTable);
}

Also try different values for SqlBulkCopy.BatchSize to adjust performance for your case. P.S. the tip applies only to MS SQL Server.

Create elegant code with Action delegate and List.ForEach method

Let's review the following code which works with generic collection:

List<Tip>tips = new
                   
                    List<Tip>(); 
  //represents a list of Tips //create SiteMapNode from each Tip
foreach (Tip tip  in tips)
{
string url = string.Format("{0}/tips/{1}.aspx", appPath, tip.Id);
SiteMapNode node = new
SiteMapNode(this,url, url, tip.Title);
node["lastmod"]=tip.PubDate.ToString("u");
AddNode(node, rootNode);
}

Although this code works well we can improve it using Action delegate and List.ForEach method. First we have to extract code to create SiteMapNode into a method:

private void AddSiteMapNode(Tip tip){
string url = string.Format("{0}/tips/{1}.aspx", appPath, tip.Id);
SiteMapNode node = new SiteMapNode(this,url,url,tip.Title);
node["lastmod"]=tip.PubDate.ToString("u");
AddNode(node, rootNode);
}

Separating it into a separate method has a few advantages, practically the ability to reuse the same logic for other uses. Now once we have this method creating SiteMapNode's from Tips collection would be: tips.ForEach(AddSiteMapNode); P.S. this tip also can be used with Array.ForEach method.

Disable Submit button after it was clicked

While submitting the form data to a server to be handled by the Click event of Submit button, it would be a good practice to disable the button. Here is a small code sample to achieve this:

btnSubmit.OnClientClick = ClientScript.GetPostBackEventReference(btnSubmit, "") + ";
  this.value='Submitting...';
  this.disabled = true;";

Note: don't apply the tip to buttons which cause validation. Such buttons require more advanced onclick handler which checks client-side validation result.

Setting focus during a validation error

The validation controls now (starting with ASP.NET 2.0) allow you to easily set focus on a control in error using the SetFocusOnError property:

<asp:RequiredFieldValidator SetFocusOnError="true" ErrorMessage="msg" ControlToValidate="TextBox1" runat="server" />

Which is better: Control or WebControl?

The System.Web.UI.Control class is the base class for all server controls. This provides the properties, methods, and events shared by all web controls. The System.Web.UI.WebControls.WebControl class derives from the Control class and adds style properties such as span, Forecolor, and Backcolor. Microsoft recommends:

if your custom control contains no user interface elements then derive from Control Class.
if your custom control provides a user interface, then derive from WebControl class.

Handling errors at the method level

1.If potential errors are recoverable in the routine
Use a combination of try…Catch blocks as a retry mechanism for error handling.
2.If useful information can be added to the exception
Create and throw a new exception with the added information.
3.If cleanup is required
Perform it in the finally block.
4.If potential errors are not recoverable in the routine
Recovery should be handled by the calling routine and its error-handling structure.

How to call a surrogate for Dispose() on StringBuilder objects

A typical use for the StringBuilder type looks like below:

class Program
{
static string UseStringBuilder(string token)
{
StringBuilder sb = new class="GramE"> StringBuilder();
int i = 10;
while (i-- > 0)
{
sb.Append(token +'\n');
}
string result = sb.ToString();
return result;}
static voidMain(string[] args)
{
Console.WriteLine(UseStringBuilder("first"));
Console.WriteLine(UseStringBuilder("second"));
} }

The issue with this code is that when sb goes out of scope it is mark for garbage collection, but the memory stored in it lingers until the garbage collector invokes its finalizer. That could amount to a lot of unused memory and hence might cost you some unnecessary garbage collections by the CLR. Given this behavior it would only look natural to call something like Dispose to take care of the underline memory buffer used in the StringBuilder. Unfortunately there is no Dispose method for this class, or any method to hint at freeing this unused memory in a deterministic way. The trick to get rid of this memory without invoking the finalizer is to set the Length to 0. The efficient code will become:

span class="keyword">classProgram
{
static string UseStringBuilder(string token)
{
StringBuilder sb = new StringBuilder();
int i = 10;
while (i-- > 0)
{
sb.Append(token + '\n');}
string result = sb.ToString();
sb.Length = 0; // this is the Dispose equivalent
return result;
}
static 
   
    void Main(string[] args)
{
Console.WriteLine(UseStringBuilder("first"));
//no need to call System.GC.Collect()
    for the unreferenced StringBuilder object Console.WriteLine(UseStringBuilder("second"));
} }

Update: use this trick with caution. There's no guarantee that future implementations of the runtime will act as described (tested only on .NET 2.0, 3.0 and 3.5). Only apply if you are working with big strings and have problems with memory/performance. Otherwise you will just complicate your code.
Thanks to Jeff Dean for pointing that out.

How to determine whether a property or a method is more appropriate for your needs

Use a method when:

The operation is a conversion, such as Object.ToString.
The operation is expensive enough that you want to communicate to the user that they should consider caching the result.
Obtaining a property value using the get accessor would have an observable side effect.
Calling the member twice in succession produces different results.
The order of execution is important. Note that a type's properties should be able to be set and retrieved in any order.
The member returns an array. Properties that return arrays can be very misleading. Usually it is necessary to return a copy of the internal array so that the user cannot change internal state. This, coupled with the fact that a user can easily assume it is an indexed property, leads to inefficient code.

P.S. this is not a comprehensive list of guidelines. See Design Guidelines for Class Library Developers for more.

Verbatim string literals

Verbatim string literal does not require the use of escape characters to define special characters. Instead, any information in the source code, including new lines, is included in the string. To define a string literal an @ symbol is placed before the opening quotation mark. Verbatim string literals are often used for specifying paths and multi-line strings:

string path = @"C:\Program Files\My Program";
//verbatim literal string path2 = "C:\\Program Files\\My Program";
//regular literalclass="keyword" string msg = @"Hello, This is a multi-line string";
//verbatim literal string msg2 = "Hello,\nThis is multi-line string";
//regular literal P.S. the only character that requires a different action is the quotation mark itself, which must be entered twice to indicate a single character.

Speed up Visual Studio 2005

Make sure Visual Studio 2005 SP1 is installed.
Turn off animation.
Go to Tools | Options | Environment and uncheck Animate environment tools.
Disable Navigation Bar.
If you are using ReSharper, you don't need VS2005 to update the list of methods and fields at the top of the file (CTRL-F12 does this nicely). Go to Tools | Options | Text Editor | C# and uncheck Navigation bar.
Turn off Track Changes.
Go to Tools | Options | Text Editor and uncheck Track changes. This will reduce overhead and speeds up IDE response.
Turn off Track Active item.
This will turn off jumping in the explorer whenever you select different files in different projects. Go to Tools | Options | Projects and Solutions and uncheck Track Active Item in Solution Explorer. This will ensure that if you are moving across files in different projects, left pane will still be steady instead of jumping around.
Turn off AutoToolboxPopulate.
There is an option in VS 2005 that will cause VS to automatically populate the toolbox with any controls you compile as part of your solution. This is a useful feature when developing controls since it updates them when you build, but it can cause VS to end up taking a long time in some circumstances. To disable this option, select the Tools | Options | Windows Forms Designer and then set AutoToolboxPopulate to False.

Optimize the launch of the Visual Studio 2005

Disable "Start Page".

1.Go to Tools | Options. 2.In Environment | Startup section, change At startup setting to Show empty environment.

Disable splash screen.

1.Open the properties of Visual Studio 2005 shortcut. 2.Add the parameter /nosplash to the target.

Close all unnecessary panels/tabs to prevent them from appearing when the IDE loads.

Conditional breakpoints in Visual Studio

You can specify a breakpoint condition which will be evaluated when a breakpoint is reached. The debugger will break only if the condition is satisfied. To specify a condition:
1.In a source window, right-click a line containing a breakpoint glyph and choose Condition from Breakpoints in the shortcut menu
2.In the Breakpoint Condition dialog box, define a boolean condition using the code in your local scope. For example, you can only break when _culture != "en-US".
3.Choose Is true if you want to break when the expression is satisfied or Has changed if you want to break when the value of the expression has changed.
4.Click OK.

Use Path.GetRandomFileName() or Path.GetTempFileName() when working with temp files

Do not reinvent function for generating unique name for temporary files. Use one of the existing methods:

System.IO.Path.GetTempFileName() - use this method if you want to create temporary file in user's temp folder.
System.IO.Path.GetRandomFileName() - use this method if you just want to generate unique file name.

Consider using System.IO.Path.Combine() instead of string concatenation

Let's review the following code for creating a file path:

public string GetFullPath(string fileName) {
string folder = ConfigurationManager.AppSettings["MyFolder"];
return folder + fileName;
}

This code is prone to error. For example, when you set the folder setting, you have to remember to make sure it ends with a slash.
To avoid such problems use Path.Combine() method which will ensure that the folder has ending slash:

public string   GetFullPath(string filename) {
string folder =  ConfigurationManager.AppSettings["MyFolder"];
return Path.Combine(folder, filename);
 }

Always check Page.IsValid in your button's EventHandler

Just because you are using ASP.NET validation controls, do not assume the page could not be submitted with invalid data. Also, just because you hide a control, do not assume buttons/textboxes/etc on it are not submit-able. It is perfectly fine to hide a control that a user should not access, but with very little code (or using a third party tool) users can easily make an HttpPost with any data they choose.

Use DebuggerStepThrough attribute to save time when debugging

When debugging code, one of the annoying things is to step into an one-line method or property. Assume that you have the following property:

private string word;
publicstring Word { get { return word; }

 set{ word = value; }
}

And you have a code that uses that property when calling a method: DoSomething(obj.Word); When you debug that line, and hit F11 to step into the method, you'll step into the get section of the property, and only then move on to the method. By placing System.Diagnostics.DebuggerStepThrough attribute above get and set sections of the property you instruct the debugger to step through that property and not into it:

public string Word
{
[System.Diagnostics.DebuggerStepThrough]
get { return word; }
[System.Diagnostics.DebuggerStepThrough]
set { word = value;}}

This instruction will cause the debugger not to step into method (property) as normal, but you can always place a breakpoint in that method and stop there.

Speed up string comparison

The Compare method compares strings in a local-aware fashion, so it has to convert the Unicode code of each character into a numeric value that reflects its position in the current culture's alphabet. For example, the Compare method considers the "b" lowercase character to come immediately after the "A" uppercase char and before the "B" uppercase char, even though the "A" and "B" characters are contiguous in the Unicode character set. This conversion activity takes time and consume CPU cycles, so you'll find that VB.NET is less efficient than VB6 at comparing strings. Using the = operator and other comparison operators doesn't help at all, because they map to the Compare method behind the scenes, so these operators suffer from the same performance loss. If you are only interested in checking whether two strings contain the same characters (in a case-sensitive comparison), you can speed up your code by using the CompareOrdinal shared method. This method is 3-4 times faster than the Compare method (or the = operator) because it just scans the two strings and compare the Unicode numeric code of each character.

Quickly move to matching brace in Visual Studio

Just press Ctrl+] and VS.NET will take you to the matching brace. It also will take you to the matching comment, region or quote depending on what is at the cursor now.

Linking a file in Visual Studio.NET

If in VS.NET you add to the current project an existing file that's located outside the current project's directory, the file is first copied in the project's directory, and then it's added to the project. However, you may want to share the same source file among multiple projects.
As a trivially simple example, perhaps you get tired of specifying the same AssemblyCompany and AssemblyCopyright strings, over and over again, in all your projects? Wouldn't it be nice to have a little two-line C# file tucked away somewhere, and include it by reference in all your projects?

[assembly: System.Reflection.AssemblyCompany(".Faithorg")][assembly:
                  System.Reflection.AssemblyCopyright("© 2009 All rights reserved.")]

To add a shared file, open the dialog to select an existing file with the Project | Add Existing Item… menu item and select the file you want to include. Then, instead of clicking the Open button, click the arrow on the left of that button, and click Link File from the list that drops down. This way you link to the original file, not to a local copy of it.

Don’t clear the stack trace when re-throwing an exception

Often, we need to put some exception handling on catch blocks (e.g., to rollback a transaction) and re-throw the exception. There are two ways of doing it. The wrong way:

try{
// Some code that throws an exception
}
catch (Exception ex)
{// some code that handles the exception
throw
   
    ex;}

Why is this wrong? Because, when you examine the stack trace, the point of the exception will be the line of the
"

throw
          style="font-size: 
          11pt"> ex;"

,
hiding the real error location.
Instead of "

throw
          style="font-size: 
          11pt"> ex;"

, which will throw a new exception and clear the stack trace,
simply use
"throw;": try{ // Some code that throws an exception}
catch (Exception ex)
{ // some code that handles the exception throw;}

If you don’t specify the exception, the throw statement will simply rethrow the very same exception the catch statement caught.
This will keep your stack trace intact, but still allows you to put code in your catch blocks.

Exceptions cause performance to suffer significantly

Do not rely on exceptions in your code and write code that avoids exceptions. Since exceptions cause performance to suffer significantly, you should never use them as a way to control normal program flow. If it is possible to detect in code a condition that would cause an exception, do so. Do not catch the exception itself before you handle that condition. Do not use exceptions to control logic. A database connection that fails to open is an exception but a user who mistypes his password is simply a condition that needs to be handled. Common scenarios include checking for null, assigning a value to a String that will be parsed into a numeric value, or checking for specific values before applying math operations.

//Unnecessary use of exception
try
{
value = 100/number;}
catch(Exception ex)
{
value = 0;
}

Quickly locate where the exceptions are thrown

How many times has this happened to you? You're working on code that's not quite functioning correctly. You suspect there's an exception being thrown somewhere, but it's being caught and ignored. Maybe this was intentional, or maybe it was poorly written code. Either way, you need to locate the problem. To do this, open the Exceptions dialog, either through the menu (Debug > Exceptions) or the keyboard shortcut (Ctrl+D, E). Under the Thrown column, check the box next to the Common Language Runtime Exceptions. Now, when an exception is thrown, VS immediately breaks at the offending line of code.

Visual Studio Full Screen Mode

You can quickly toggle into Full Screen mode by pressing Shift+Alt+Enter.

Incremental search in Visual Studio

1.Press Ctrl+I. 2.Start typing the text you are searching for. Note: you'll see the cursor jump to the first match, highlighting the current search string. 3.Press Ctrl+I again to jump to the next occurrence of the search string. 4.To stop search, press Esc. Advanced tip: Press Ctrl+Shift+I to search backwards.

Auto-complete the word in Visual Studio 2005

Type the first few characters of a control/variable/type name and hit Ctrl+Space or Alt+RightArrow to auto-complete the word. If there is more than one possibility Intellisense suggestions will pop up a window with available options.

Always set the "applicationName" property when configuring Membership and other Providers

Users created with the membership API will be associated with applicationName value specified in provider declaration in web.config file. This diagramm shows how user is associated with applicationName in database: When no applicationName attribute is configured, ASP.NET uses the application vroot path within the web-server to automatically calculate the applicationName to use when adding data to an ASP.NET Application Service database.
Now let's assume you develop an ASP.NET 2.0 application locally using Membership, Roles or Profile features and you haven't specified applicationName attribute. You create several new users. Because applicationName property was not specified your users were associated with auto calculated value (something like "/WebSite1"). This works fine when the application continues to run in the "/WebSite1" application virtual path. But if it is copied to another location or server with a different virtual path (for example: "/app1" or more commonly just "/"), then when the Membership APIs are used they will not "see" the users already in our database – since they will lookup membership data using a different application name and filter the users in the application_Users table accordingly. That is why you'll get a "Login attempt unsuccessful, please try again." message when you try to login.
The best way to prevent this from ever happening is to always specify the "applicationName" attribute when declaring your providers. One good default value to use is "/" – which is the root application name. This is the value specified for the default provider that ships with ASP.NET 2.0 (which by default stores the application service data within the ASPNETDB.MDF file under /app_data), and is why if you don't override the provider settings it will work if you copy an app to another machine. P.S. The reason why the applicationName setting even exists in the first place is so that you can map multiple applications and sites to the same database.

Don't forget to <clear/> when adding providers

You want to configure ASP.NET 2.0 to store your Membership/Role Management/Profile data within a remote SQL database. You decide to register a new provider within your web.config file like below:

<membership> <providers> <add name="AspNetSqlMembershipProvider"
  ,type="System.Web.Security.SqlMembershipProvider,
      System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
 
  connectionStringName="MyDatabase"
enablePasswordRetrieval="false" 
   
    enablePasswordReset="true"
   
    requiresQuestionAndAnswer="true" requiresUniqueEmail="false"
passwordFormat="Hashed" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="7" 
minRequiredNonalphanumericCharacters="1"
passwordAttemptWindow="10"
passwordStrengthRegularExpression=""
applicationName="/"/>
</providers> </membership>

When you run your application on a machine without SQL Express, though, you see some weird behavior. You might get a SQL error like so:
An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) The root cause of the above problem rests in how the new provider was registered within the web.config file.
The <providers> section within the web.config file is implemented as a collection, and so it is possible to register multiple providers at the same time (this is useful when you want to have some users authenticated using one Membership store, and others authenticated using a separate Membership store). By default ASP.NET 2.0 registers a set of default SQL Express providers within the root web.config file on your machine that create a SQL Express database within your /app_data directory to store/manage membership/role/profile data when you first access it. Because this is registered at the machine-wide level, all provider collections by default inherit this registration. Unless you explictly <clear/> or override the inherited value, your application will have this default membership/role/profile provider registered. Because the above web.config file simply added a new provider -- and didn't clear or replace the default provider registration -- the above application now has two Membership providers configured. When you do a Membership.CreateUser() call in your code, ASP.NET will attempt to create the user in both membership databases. If you don't have SQL Express installed on your system, the create-user attempt will fail for this database - which leads to the errors and/or weird behavior above.

To fix this problem add an explicit <clear/> directive before your <add/> statements within your web.config file:

<membership> <providers> <add name="AspNetSqlMembershipProvider" ,
          type="System.Web.Security.SqlMembershipProvider,
          System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
connectionStringName="MyDatabase"
enablePasswordRetrieval="false" enablePasswordReset="true"
requiresQuestionAndAnswer="true" requiresUniqueEmail="false"
 passwordFormat="Hashed" maxInvalidPasswordAttempts="5"
          minRequiredPasswordLength="7" minRequiredNonalphanumericCharacters="1"
          passwordAttemptWindow="10" passwordStrengthRegularExpression="" applicationName="/"/>
</providers> </membership>

Note that you must do this for each provider declaration that you register. So if you are adding providers for <roles> and <profile>, make sure you add the <clear/> directive in their providers section as well.

How to perform DateTime calculations in a right way

When coding, be careful if you need to perform DateTime calculations (add/subtract) on values representing time zones that practice daylight savings time. Unexpected calculation errors can result. Instead, convert the local time value to universal time, perform the calculation, and convert back to achieve maximum accuracy

. DateTime d; d = DateTime.Parse class="GramE">("Oct 26, 2003 12:00:00 AM");
//date assignment d = d.ToUniversalTime().AddHours(3.0).ToLocalTime();
//' - displays 10/26/2003 02:00:00 AM – Correct! MessageBox.Show(d.ToString());
Working with DateTime structs seems to be simple, but it's not

How to maintain the position of the scrollbar on postbacks

In ASP.NET 1.1 it was a pain to maintain the position of the scrollbar when doing a postback operation. This was especially true when you had a grid on the page and went to edit a specific row. Instead of staying on the desired row, the page would reload and you'd be placed back at the top and have to scroll down. In ASP.NET 2.0 you can simply add the MaintainScrollPostionOnPostBack attribute to the Page directive:
<%Page Language="C#" ... MaintainScrollPositionOnPostback="true" %>

strongly-typed access to previous page during cross-page postback

ASP.NET 2.0 introduced the concept of cross-page postbacks where one page could postback information to a page other than itself. This is done by setting the PostBackUrl property of a button to the name of the page that the button should postback data to. Normally, the posted data can be accessed by doing something like
PreviousPage.FindControl("ControlID").
However, this requires a cast if you need to access properties of the target control in the previous page (which you normally need to do). If you add a public property into the code-behind page that initiates the postback operation, you can access the property in a strongly-typed manner by adding the PreviousPageType directive into the target page of the postback. For example, if you have a page called Default.aspx that exposes a public property that returns a Textbox that is defined in the page, the page that data is posted to (lets call it SearchResults.aspx) can access that property in a strongly-typed manner (no FindControl() call is necessary) by adding the PreviousPageType directive into the top of the page:
<%@ PreviousPageType VirtualPath="Default.aspx" %>
By adding this directive, the code in SearchResults.aspx can access the TextBox defined in Default.aspx in a strongly-typed manner. The following example assumes the property defined in Default.aspx is named
SearchTextBox. TextBox tb = PreviousPage.SearchTextBox;
This code obviously only works if the previous page is Default.aspx. PreviousPageType also has a TypeName property as well where you could define a base type that one or more pages derive from to make this technique work with multiple pages.

How to get virtual path of web application

Getting the virtual paths local to server is pretty straight forward most of the time; just use Page.ResolveURL("~/whatever"). But what if you're in the BLL part of your app? Seeing as the Page.ResolveURL is not a static method you would have to create a new instance of Page before you can reference it... not good enough. In BLL use System.Web.HttpRuntime.AppDomainAppVirtualPath static property to get local virtual path of web application:
string url = HttpRuntime.AppDomainAppVirtualPath + "/whatever";
Note: if web application is in a server root folder AppDomainAppVirtualPath returns just "/". If web application is in a non-root folder it returns virtual path of the folder without "/" in the end.

strongly-typed access to Master Pages controls

If you have public properties defined in a Master Page that you'd like to access in a strongly-typed manner you can add the MasterType directive into a page as shown next:
<%MasterType VirtualPath="MasterPage.master" %>
You can then access properties in the target master page from a content page by writing code like the following:
this.Master.HeaderText = "Label updated using MasterType directive with VirtualPath attribute.";

Conditional compilation with ConditionalAttribute

It is possible to conditionally compile code out of the final product, this is usually useful when you want to have extra checks in the code (asserts, invariant checking) during development and testing, in debug mode, but do not want to incur the cost of this checking in the final release product.
Just put all of the checking into a method and place Conditional attribute on it.

public sealed classDebug { [Conditional("DEBUG")]
 publicstatic void Assert(bool condition, string message) { 
                
                 TraceInternal.Assert(condition,message);
                     } }

What this actually does is tell the compiler to only call the method when the supplied preprocessor symbol is defined.
The method will still be compiled and will still exist in the assembly. So, in a debug build a program that looks like this:

static  void Main(string[] args) {
Debug.Assert(true,"Thiscondition must be true");}
//will still look like that, but when compiled in release mode, will    look like this:
private static void Main(string[]args)
{
}

Note: the Debug classe of the .NET Framework use the ConditionalAttribute. So you don't have to worry about any performance hit whatsoever when you call various methods of this class as a debugging aid. These calls just won't make it in the release build.

How to locate control nested inside of another control

Finding controls within a Page's control hierarchy can be painful but if you know how the controls are nested you can use the lesser known "$" shortcut to find controls without having to write recursive code. The following example shows how to use the DefaultFocus property to set the focus on a textbox that is nested inside of a FormView control. Notice that the "$" is used to delimit the nesting:

<form      id="form1" DefaultFocus="formVw$txtName"
                   
                    runat="server"> <div>
<asp:FormView ID="formVw"
   
    runat="server"><ItemTemplate>
Name:<asp:TextBox 
       
        ID="txtName" 
           
            runat="server"Text='<%#Eval("FirstName") + " " + Eval("LastName")%>' /></ItemTemplate>
</asp:FormView></div>
</form>
This little trick can also be used on the server-side when calling FindControl():
TextBox tb = this.FindControl("form1$formVw$txtName")
as TextBox;
if (tb != null)
{
/Access TextBox control
}

How to set the default focus to a control when the page loads

This is another extremely simple thing that can be done without resorting to writing JavaScript. If you only have a single textbox (or two) on a page why should the user have to click in the textbox to start typing? Shouldn't the cursor already be blinking in the textbox so they can type away? Using the DefaultFocus property of the HtmlForm control you can easily do this.

<form id="frm"  DefaultFocus="txtUserName" runat="server"></form>

GridView Tips and Tricks

The web.config holding the connection will look similar to the following:

<configuration> <appSettings/> <connectionStrings>
               
                <add name="NorthwindConnectionString" connectionString="Data Source =

(local);IntegratedSecurity = SSPI; Initial Catalog=Northwind;"/>
</connectionStrings> </configuration>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
              <title>GridView Tips and Tricks </title>
              </head>
              <body>
<form id="form1" runat="server">
              <div>
              <asp:GridViewID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="CategoryID"
DataSourceID= "SqlDataSource1"
              ShowFooter="true" AllowPaging="True" AllowSorting="True" PageSize="5"
 OnRowDataBound="GridView1_RowDataBound">
<Columns> <asp:TemplateField
HeaderText="CategoryID" InsertVisible="False" SortExpression="CategoryID">
              <ItemTemplate><asp:LabelID="lblCategoryID" runat="server" Text='<%# Bind("CategoryID")%>'>
              </asp:Label></ItemTemplate> </asp:TemplateField>
              <asp:TemplateField HeaderText="CategoryName"SortExpression="CategoryName">
              <EditItemTemplate>
              <asp:TextBox ID="txtCategoryName" runat="server" Text='<%#Bind("CategoryName") %>'> </asp:TextBox>
</EditItemTemplate> <ItemTemplate><asp:Label ID="lblCategoryName" runat="server" Text='<%#Bind("CategoryName")%>'>
</asp:Label></ItemTemplate> </asp:TemplateField> <asp:TemplateFieldHeaderText="Description" 
SortExpression="Description">
              <EditItemTemplate><asp:TextBoxID="txtDesc" runat="server" Text='<%# Bind("Description")%>'>
</asp:TextBox></EditItemTemplate> <ItemTemplate><asp:Label ID="lblDesc" runat="server"

Text='<%#Bind("Description") %>'></asp:Label>
</ItemTemplate> </asp:TemplateField> </Columns></asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="Data Source=SUPROTIM;Initial

Catalog=Northwind;Integrated Security=True"
ProviderName="System.Data.SqlClient"
SelectCommand="SELECT
    [CategoryID],[CategoryName], [Description] FROM [Categories]"
UpdateCommand="UPDATE
    [Categories]SET [CategoryName] = @CategoryName, [Description] = @Description WHERE
    [CategoryID]= @CategoryID"/>
</div> </form> </body> </html>

Enable Disable Controls inside a GridView

There are at times when you have to disable controls on some rows, when a certain condition is satisfied. In this snippet, we will see how to disable editing for rows that have the CategoryName as ‘Confections’. Use the following code:

C#

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs
   
    e)   {
if (e.Row.RowType ==DataControlRowType.DataRow)
 { if (e.Row.DataItem!=
   
    null)
 {
 Label lblControl=(Label)e.Row.Cells[2].FindControl("lblCategoryName");
 if(lblControl.Text=="Confections")
 { e.Row.Cells[0].Enabled= 
   
    false; } }  } }

VB.NET
 Protected Sub 
   
    GridView1_RowDataBound(ByVal 
   
    sender As 
       
        Object,ByVale
   
    As GridViewRowEventArgs)
     
      If e.Row.RowType
    = DataControlRowType.DataRow Then     
           
            If Not
   
    e.Row.DataItem Is
        Nothing Then Dim lblControl 
               
                As Label= 
                   
                    CType(e.Row.Cells(2).FindControl("lblCategoryName"),Label) 
 
  If lblControl.Text = "Confections"
 
  Then     e.Row.Cells(0).Enabled=
 
  False     
      End If End If End
          If
 End Sub

Adding Arrows for Sorting Columns in a GridView

>When you are sorting the columns in a GridView, it would be a nice to have feature, to display arrows which depict either an ascending or descending sort as shown below. Create a folder called ‘images’ and add two small images called up.gif and down.gif:

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e) { 
 if (e.Row.RowType == DataControlRowType.Header)
 {   foreach    (TableCell cell 
     
      in e.Row.Cells) {
 if (cell.HasControls())
      {
   
    LinkButton btnSort = (LinkButton)cell.Controls[0];
   
    Image image = new
   
    Image();     if(btnSort.Text == GridView1.SortExpression)
     {
       
        if (GridView1.SortDirection == 
           
            SortDirection.Ascending) 
       
        {  image.ImageUrl
            = "images/up.gif"; } else 
               
                {    image.ImageUrl = "images/down.gif";  
        } }
           

            cell.Controls.Add(image); }
               
                }

VB.NET
Protected Sub GridView1_RowDataBound(ByVal sender As Object,ByVal e As GridViewRowEventArgs)
If e.Row.RowType = DataControlRowType.Header   Then   
 For Each cell As TableCell In e.Row.Cells
 If cell.HasControls()   Then
 Dim btnSort As LinkButton=CType(cell.Controls(0),LinkButton)
 Dim image As Image = New Image() If btnSort.Text
  = GridView1.SortExpression Then 
 If GridView1.SortDirection= SortDirection.Ascending Then
 image.ImageUrl="images/up.gif"
Else  image.ImageUrl="images/down.gif"
 End If 
                  End
If   cell.Controls.Add(image)               
 End If                        
 Next cell

How to programmatically hide a column in the GridView

There are two conditions to be checked in the Page_Load to hide a columns in the GridView, let us say the 3^rd column: If ‘AutoGenerateColumns’ = True on the GridView

C#
GridView1.HeaderRow.Cells[2].Visible= false;
foreach (GridViewRow
gvr in GridView1.Rows)
{
 gvr.Cells[2].Visible = false;
 }

VB.NET
GridView1.HeaderRow.Cells(2).Visible = 
   
    False
For Each
gvr As GridViewRow
   
    In GridView1.Rows
 gvr.Cells(2).Visible = False 
   
    Next
        gvr

If ‘AutoGenerateColumns’ = False on the GridView

C#
GridView1.Columns[2].Visible=false;

VB.NET

GridView1.Columns(2).Visible=False

Handling Concurrency Issues in GridView

>If you are using the SqlDataSource (or ObjectDataSource), you can use both the SqlDataSource.ConflictDetection and OldValuesParameterFormatString property to handle concurrency issues. These two properties together control how to perform updates and delete operations when the underlying data source changes, while the operation is being carried out. The original and modified versions of each column can be tracked using the two properties. Displaying Empty Data in a GridView When there are no results returned from the GridView control’s data source, the short and simple way of displaying a message to the user, is to use the GridView’s EmptyDataText property.

<asp:GridView ID="GridView1" runat="server" 
     
      AutoGenerateColumns="False"
     
      DataKeyNames="CategoryID"  DataSourceID="SqlDataSource1" 
                 
                  EmptyDataText="No data available"
         
          ShowFooter="true"AllowPaging="True"
             
              AllowSorting="True" 
                     
                      PageSize="5"OnRowDataBound="GridView1_RowDataBound">

Note: You can also add style to the EmptyDataText by using the EmptyDataRowStyle property.

Displaying an Image in case of Empty Data in a GridView

As an alternative to using the EmptyDataText property, if you need to display an image or any HTML/ASP.NET control, you can use the EmptyDataTemplate. In this snippet below, we are using the image control in the <EmptyDataTemplate> to display an image.

<asp:GridView ID="GridView1"
runat="server"
AutoGenerateColumns="False" DataKeyNames="CategoryID" DataSourceID="SqlDataSource1"
           
            ShowFooter="true"
           
            AllowPaging="True"
           
            AllowSorting="True"
           
            PageSize="5"
           
            OnRowDataBound="GridView1_RowDataBound">  
                   
                    <EmptyDataTemplate> <asp:Image 
     
      id="imgNoData" ImageUrl="~/images/NoDataFound.jpg" AlternateText="No
                  data found"
                     
                      runat="server"/> </EmptyDataTemplate>

How to Bind a List<> to a GridView

Let us see how to bind a List<> to a GridView. We assume that the ‘AutoGenerateColumns’ = True.

We will create a class called Employees and bind it to the GridView with the help of a List<>. Create a class called ‘Employees’

C#
public   class Employee{
private string enm;
    

   
    private int ageofemp; 
                      private string department; 
public string EName 
get { return
enm;}
set{enm = value;}
} 
public int Age {
get{ return ageofemp; }
 set{ ageofemp = value;
}
 }
 public string Dept  { 
 get{
 return department;
}
set
{
 department = value;
}
 }
    

   
    public Employee(string ename,
   
    int age, 
       
        string dept)
 {
this.enm = ename;
this.ageofemp = age;
this.department = dept;
}

VB.NET
Public Class Employee
Private enm As String Private
   
    ageofemp As IntegerPrivate department 
            As String
Public
    Property EName()As
        String
Get

Return enm
 End
    Get
Set(ByVal value 
        As String)
enm = value     End
    Set
 End
    Property
 Public
    Property Age() m As Integer
 Get
Return ageofemp
 End Get
   
    Set(ByVal value 
       
        As Integer) ageofemp = value
 End Set
 End
    Property
 Public
    Property Dept() As
   
    String
 Get
 Return department
 End
    Get
 Set(ByVal value 
       
        As String)
    department = value
End Set
 End
    Property
 Public
    Sub New(ByVal
   
    ename As 
       
        String, 
           
            ByVal age As Integer, ByVal
   
    dept As String)
 Me.enm = ename
     
      Me.ageofemp = age 
Me.department = dept
  End
    Sub
End Class

Bind the ‘Employee’ data to the GridView using a List<>

C#

protected void Page_Load(object sender,EventArgs e)
 { System.Collections.Generic.List<Employee> emp = new System.Collections.Generic.List<Employee>();
emp.Add(new Employee("Harsha", 22, "Marketing"));
emp.Add(new Employee("Thomas", 28, "Advertising"));
emp.Add(new Employee("Pervez", 23, "Advertising"));
emp.Add(new Employee("Rouf", 44, "Production"));
emp.Add(new Employee("shabir", 28, "PPC"));
                      GridView1.DataSource = emp;
                      GridView1.DataBind();
                      }

VB.NET
Protected  Sub Page_Load(ByVal sender As Object,ByVal e  As EventArgs)
Dim emp  As List(OfEmployee)=New List(Of Employee)() emp.Add(New Employee("Harsha",22,"Marketing"))
 emp.Add(New Employee("Thomas",28,"Advertising"))
 emp.Add(New Employee("Pervez",23,"Advertising"))
 emp.Add(New Employee("Rouf",  44,"Production"))
 emp.Add(New Employee("shabir",28,"PPC"))
 GridView1.DataSource = emp
 GridView1.DataBind()
 End Sub

Change the color of a GridView Row based on some condition

C#
protected void GridView1_RowCreated(object sender, GridViewRowEventArgs  e)
{
if (e.Row.DataItem !=
   
    null)
{
DataRowView drv = (DataRowView)e.Row.DataItem;
string catName = Convert.ToString(drv["CategoryName"]);
 if (catName.Trim()
    =="Confections")
e.Row.BackColor = System.Drawing.Color.LightBlue;
                      }
 }

VB.NET

Protected  Sub GridView1_RowCreated(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
If Not e.Row.DataItem Is Nothing Then
Dim drv  As DataRowView   CType(e.Row.DataItem,DataRowView)
Dim catName As String = Convert.ToString(drv("CategoryName"))
If catName.Trim()="Confections"       Then
e.Row.BackColor = System.Drawing.Color.LightBlue
End If
    

    End If
End Sub

How to create an Image Command Field Column and add to the GridView at runtime

if (!Page.IsPostBack)
{
CommandField cmdField = new CommandField();
                      cmdField.ButtonType = ButtonType.Image;
cmdField.SelectImageUrl = "~/Images/Home_Np1.GIF";
                      cmdField.ShowSelectButton = true; cmdField.HeaderText = "Select"; 
GridView1.Columns.Add(cmdField);
 GridView1.DataBind(); }

VB.NET

If (Not(Page.IsPostBack))Then
Dim cmdField As CommandField = 
       
        New CommandField()
cmdField.ButtonType = ButtonType.Image
cmdField.SelectImageUrl = "~/Images/Home_Np1.GIF" cmdField.ShowSelectButton =True
cmdField.HeaderText = "Select"
GridView1.Columns.Add(cmdField) GridView1.DataBind() 
                      End If

How to display images in the GridView from Filesystem based on an existing Column Let us imagine that you have a folder ‘Images’ where you have stored images for each category. Eg: 1.GIF, 2.GIF, 3.GIF and so on. Now you want to display a different image based on each CategoryID. So for CategoryID = 1, the image is 1.GIF; for CategoryID=2, the image is 2.GIF and so on.

 <asp:TemplateField> <ItemTemplate>
  <asp:Image 
       
        runat="server" 
           
            ImageUrl='<%#
    "~/Images/"+ Eval("CategoryID")
    + ".GIF"%>'>
</asp:Image>
 </ItemTemplate>
 </asp:TemplateField>

How to Retrieve Images from the database and display it in a GridView

I will assume that we have a image column called CatImg in the Categories table. The first step would be to create an ImageHandler. In such scenarios such as the gridview, usually prefer to go in for a handler when I have to return binary data directly from the database. It gives more control on the resource returned. Moreover it is a preferred solution when you have to set the image programmatically. To add a handler, right click project > Add New Item > Generic Handler > ShowImage.ashx. The code shown below, uses the Request.QueryString["id"] to retrieve the CategoryID from it. The ID is then passed to the ‘ShowCatImage()’ method where the image is fetched from the database and returned in a MemoryStream object. We then read the stream into a byte array. Using the OutputStream.Write(), we write the sequence of bytes to the current stream and you get to see your image.

C#
<%@WebHandler Language="C#" Class="ShowImage"%>
using System;
using System.Configuration;
using System.Web;
using System.IO;
using System.Data;
using System.Data.SqlClient;
public class ShowImage : IHttpHandler
{
public void ProcessRequest(HttpContext context)
 {
Int32 catid;
if (context.Request.QueryString["id"] != null)
 catid = Convert.ToInt32(context.Request.QueryString["id"]);
else 
throw new 
   
    ArgumentException("No parameter specified");
 context.Response.ContentType = "image/jpeg";
 Stream strm = ShowCatImage(catid);
 byte[] buffer =new byte[4096];
int byteSeq = strm.Read(buffer,
    0, 4096);
while (byteSeq >
    0)
{
 context.Response.OutputStream.Write(buffer, 0, byteSeq);
 byteSeq = strm.Read(buffer, 0, 4096);
}
//context.Response.BinaryWrite(buffer);
 }
 public 
   
    Stream ShowCatImage(int 
   
    catid)
 {
string conn = ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;
SqlConnection connection = 
   
    new SqlConnection(conn);
string sql = "SELECT catImg FROM Categories WHERE CategoryID = @ID";
SqlCommand cmd = new SqlCommand(sql,
    connection);
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@ID",
    catid);
connection.Open();
object img = cmd.ExecuteScalar();
try
{
 return
    new MemoryStream((byte[])img);
}
catch
 {
 return
    null;
}
finally
{
 connection.Close();
}
 }
public
    bool IsReusable
 {
get{
   
    return
        false;}
 }
}

VB.NET
<%@ WebHandler Language="vb" Class="ShowImage"%>
Imports System
Imports System.Configuration
Imports System.Web
Imports System.IO
Imports System.Data
Imports System.Data.SqlClient
Public Class ShowImage
Implements IHttpHandler
Public Sub ProcessRequest(ByVal context 
       
        As HttpContext) 
           
            Implements IHttpHandler.ProcessRequest
Dim catid As Int32
If Not
    context.Request.QueryString("id") 
        Is Nothing Then
 catid = Convert.ToInt32(context.Request.QueryString("id"))
Else
Throw
    New ArgumentException("No parameter specified")
End If
 context.Response.ContentType = "image/jpeg"
 Dim strm 
   
    As Stream = ShowCatImage(catid)
 Dim buffer As Byte()
    = New
        Byte(4095){}
 Dim byteSeq As Integer = strm.Read(buffer, 0, 4096)
 Do While
    byteSeq > 0
 context.Response.OutputStream.Write(buffer,0, byteSeq)
 byteSeq = strm.Read(buffer, 0, 4096)
 Loop
 'context.Response.BinaryWrite(buffer);
 End
    Sub
 Public
    Function ShowCatImage(ByVal
   
    catid As Integer)
   
    As Stream
 Dim conn 
    As String = ConfigurationManager.ConnectionStrings

    ("NorthwindConnectionString").ConnectionString
 Dim connection As SqlConnection = 
       
        New SqlConnection(conn)
 Dim sql
    As String = "SELECT catImg FROM Categories WHERE CategoryID = @ID"
 Dim cmd 
   
    As SqlCommand = New
    SqlCommand(sql, connection)
 cmd.CommandType = CommandType.Text
 cmd.Parameters.AddWithValue("@ID", catid)
 connection.Open()
 Dim img 
   
    As Object = cmd.ExecuteScalar()
 Try
 Return
    New MemoryStream(CType(img,Byte()))
 Catch
 Return
    Nothing
 Finally
 connection.Close()
 End
    Try End
        Function
 Public
    ReadOnly Property IsReusable() 
       
        As Boolean
   
    Implements IHttpHandler.IsReusable
 Get
 Return
    False End
        Get End Property End Class

To access this image in the GridView based on the CategoryID, just add the following:

<asp:TemplateField><ItemTemplate>
<asp:Image 
       
        runat="server" 
           
            ImageUrl='<%#"ShowImage.ashx?id="
    + Eval("CategoryID")%>'>
</asp:Image>
</ItemTemplate> </asp:TemplateField>

How to programmatically enable/disable a control in the GridView when in the Edit Mode

If you want to quickly take a decision whether to enable or disable a control when the user edits the row, then use the Enabled attribute and set it to a method that returns a bool value:

<asp:TemplateFieldHeaderText="CategoryName"SortExpression="CategoryName">
     
      <EditItemTemplate> <asp:TextBox 
                 
                  ID="txtCategoryName" 
                     
                      runat="server" 
Enabled='<%#
                      EnableDisableTextBox()%> 
   
    ' Text='<%#Bind("CategoryName")
             
              %> '></asp:TextBox>
 </EditItemTemplate>
 <ItemTemplate>
<asp:Label 
       
        ID="lblCategoryName" 
           
            runat="server" 
               
                Text='<%#Bind("CategoryName")%>'> </asp:Label>
 </ItemTemplate>
 </asp:TemplateField>

C#
protected bool EnableDisableTextBox()
 {
if (1 == 1)
return 
 false;
 }

VB.NET
Protected Function EnableDisableTextBox() As
    Boolean
If 1 = 1 Then
Return False End If End Function

You can test this code by adding a CommandField to the GridView as shown below
<asp:CommandField ButtonType="Link" ShowEditButton="true" />

How to loop through all the rows in all the pages of a GridView

One simple way to loop through all the rows in all the pages of a GridView is to access its DataSource. In this example, we will loop through the SQLDataSource to retrieve all the rows in a GridView and access its cell value. You can modify the logic depending on the type of controls you have added to the GridView

C#
protected void Button1_Click(object sender, EventArgs e)
                        {
                        DataSourceSelectArguments dsaArgs = new DataSourceSelectArguments();
DataView view = (DataView)SqlDataSource1.Select(dsaArgs);
DataTable dt = view.ToTable();
for (int i = 0;i < dt.Rows.Count; i++)
                        {
for (int j = 0; j < dt.Columns.Count; j++)
                        {
string s = dt.Rows[i][j].ToString();
                        }
                        }
                        }
                        }

VB.NET
Protected Sub Button1_Click(ByVal sender 
   
    As Object, ByVal ByVale As EventArgs)
Dim dsaArgs As DataSourceSelectArguments = New DataSourceSelectArguments()
Dim view As DataView = CType(SqlDataSource1.Select(dsaArgs), DataView)
Dim dt As DataTable = view.ToTable()
For i As Integer = 0 To dt.Rows.Count(-1)
For j As Integer = 0 To dt.Columns.Count(-1)
Dim s As String = dt.Rows(i)(j).ToString()
Next j
Next i
End Sub

Add or Remove Trailing Slash

Many web applications use "virtual URLs" - that is the URLs that do not directly map to the file and directory layout on web server’s file system. An example of such application may be an ASP.NET MVC application with URL format similar to this: http://stackoverflow.com/questions/60857/modrewrite-equivalent-for-iis-7-0 ) or a PHP application with URL format that looks like this: http://ruslany.net/2008/11/url-rewrite-module-release-to-web/) If you try to request these URLs with or without trailing slash you will still get the same page. That is OK for human visitors, but may be a problem for search engine crawlers as well as for web analytics services. Different URLs for the same page may cause crawlers to treat the same page as different pages, thus affecting the page ranking. They will also cause Web Analytics statistics for this page to be split up. This problem is very easy to fix with a rewrite rule. Having or not having a trailing slash in the URL is a matter of taste, but once you’ve made a choice you can enforce the canonical URL format by using one of these rewrite rules: To always remove trailing slash from the URL:

<rule name="Remove
                    trailing slash" stopProcessing="true">
  <match url="(.*)/$" />
  <conditions>
    <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
    <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
  </conditions>
  <action type="Redirect" redirectType="Permanent" url="{R:1}" />
</rule>

To always add trailing slash to the URL:

<rule name="Add trailing slash" stopProcessing="true">
  <match url="(.*[^/])$" />
 
  <conditions>
    <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
    <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
  </conditions>
  <action type="Redirect" redirectType="Permanent" url="{R:1}/" />
</rule>

Enforce Lower Case URLs

A problem similar to the trailing slash problem may happen when somebody links to your web page by using different casing,

e.g. http://ruslany.net/2008/07/IISNET-Uses-Url-Rewrite-Module/ vs. http://ruslany.net/2008/07/iisnet-uses-url-rewrite-module/. In this case again the search crawlers will treat the same page as two different pages and two different statistics sets will show up in Web Analytics reports. What you want to do is to ensure that if somebody comes to your web site by using a non-canonical link, then you redirect them to the canonical URL that uses only lowercase characters:

<rule name="Convert to lower case" stopProcessing="true">
  <match url="[A-Z]" ignoreCase="false" />
  <action type="Redirect" url="{ToLower:{R:0}}" redirectType="Permanent" />
 </rule>

Canonical Hostnames

Very often you may have one IIS web site that uses several different host names. The most common example is when a site can be accessed via http://www.yoursitename.com and via http://yoursitename.com. Or, perhaps, you have recently changed you domain name from oldsitename.com to newsitename.com and you want your visitors to use new domain name when bookmarking links to your site. A very simple redirect rule will take care of that:

<rule name="Canonical Host Name" stopProcessing="true">
  <match url="(.*)" />
  <conditions>
    <add input="{HTTP_HOST}" negate="true" pattern="^ruslany\.net$" />
  </conditions>
  <action type="Redirect" url="http://ruslany.net/{R:1}" redirectType="Permanent" />
 </rule>

To see an example of how that works try browsing to http://www.ruslany.net/2008/10/aspnet-postbacks-and-url-rewriting/. You will see in the browser’s address bar that "www" is removed from the domain name.

Redirect to HTTPS

When a site that requires SSL is accessed via non-secure HTTP connection, IIS responds with HTTP 403 (Unauthorized) status code. This may be fine if you always expect that your site visitors will be typing "https://…" in the browser’s address bar. But if you want your site to be easily discoverable and more user friendly, you probably would not want to return 403 response to visitors who came over unsecure HTTP connection. Instead you would want to redirect them to the secure equivalent of the URL they have requested. A typical example is this URL: http://www.paypal.com. If you follow it you will see that browser gets redirected to https://www.paypal.com. With URL Rewrite Module you can perform this kind of redirection by using the following rule:

<rule name="Redirect to HTTPS" stopProcessing="true">
  <match url="(.*)" />
  <conditions>
    <add input="{HTTPS}" pattern="^OFF$" />
  </conditions>
  <action type="Redirect" url="https://{HTTP_HOST}/{R:1}" redirectType="SeeOther" />
 </rule>

Note that for this rule to work within the same web site you will need to disable "Require SSL" checkbox for the web site. If you do not want to do that, then you can create two web sites in IIS – one with http binding and another with https binding – and then add this rule to the web.config file of the site with http binding.

Return HTTP 503 Status Code in Response

HTTP status code 503 means that the server is currently unable to handle the request due to maintenance. This status code implies that the outage is temporary, so when search engine crawler gets HTTP 503 response from your site, it will know not to index this response, but instead to come back later. When you stop the IIS application pool for your web site, IIS will return HTTP 503 for all requests to that site. But what if you are doing maintenance to a certain location of the web site and you do not want to shut down the entire site because of that? With URL Rewrite Module you can return 503 response only when HTTP requests are made to a specific URL path:

<rule name="Return 503" stopProcessing="true">
  <match url="^products/sale/.*" />
  <action type="CustomResponse" statusCode="503"
       subStatusCode="0"
       statusReason="Site is unavailable"
       statusDescription="Site is down for maintenance" />
 </rule>

Prevent Image Hotlinking

Image Hotlinking is the use of an image from one site into a web page belonging to a second site. Unauthorized image hotlinking from your site increases bandwidth use, even though the site is not being viewed as intended. There are other concerns with image hotlinking, for example copyrights or usage of images in an inappropriate context. With URL Rewrite Module, it is very easy to prevent image hotlinking. For example the following rewrite rule prevents hotlinking to all images on a web site http://ruslany.net/:

<rule name="Prevent image hotlinking">
  <match url=".*\.(gif|jpg|png)$"/>
  <conditions>
    <add input="{HTTP_REFERER}" pattern="^$" negate="true" />
    <add input="{HTTP_REFERER}" pattern="^http://ruslany\.net/.*$" negate="true" />
  </conditions>
  <action type="Rewrite" url="/images/say_no_to_hotlinking.jpg" />
 </rule>

This rule will rewrite a request for any image file to /images/say_no_to_hotlinking.jpg only if the HTTP Referer header on the request is not empty and is not equal to the site’s domain.

Reverse Proxy To Another Site/Server

By using URL Rewrite Module together with Application Request Routing module you can have IIS 7 act as a reverse proxy. For example, you have an intranet web server and you want to expose its content over internet. To enable that you will need to perform the following configuration steps on the server that will act as a proxy: Step1: Check the "Enable proxy" checkbox located in Application Request Routing feature view is IIS Manager. Step2: Add the following rule to the web site that will be used to proxy HTTP requests:

<rule name="Proxy">
  <match url="(.*)" />
  <action type="Rewrite" url="http://internalserver/{R:1}" />
 </rule>

Note the http:// prefix in the rewrite rule action. That is what indicates that this request must be proxy’ed, instead of being rewritten. When rule has "Rewrite" action with the URL that contains the protocol prefix, then URL Rewrite Module will not perform its standard URL rewriting logic. Instead it will pass the request to Application Request Routing module, which will proxy that request to the URL specified in the rule.

Preserve Protocol Prefix in Reverse Proxy

The rule in previous tip always uses non-secure connection to the internal content server. Even if the request came to the proxy server over HTTPS, the proxy server will pass that request to the content server over HTTP. In many cases this may be exactly what you want to do. But sometimes it may be necessary to preserve the secure connection all the way to the content server. In other words, if client connects to the server over HTTPS, then the proxy should use "https://" prefix when making requests to content server. Similarly, if client connected over HTTP, then proxy should use "http://" connection to content server. This logic can be easily expressed by this rewrite rule:

<rule name="Proxy">
  <match url="(.*)" />
  <conditions>
    <add input="{CACHE_URL}" pattern="^(https?)://" />
  </conditions>
  <action type="Rewrite" url="{C:1}://internalserver/{R:1}"
 
  />
 </rule>

Rewrite/Redirect Based on Query String Parameters

When rewriting/redirection decisions are being made by using values extracted from the query string, very often one cannot rely on having the query string parameters always listed in exact same order. So the rewrite rule must be written in such a way so that it can extract the query string parameters independently of their relative order in the query string. The following rule shows an example of how two different query string parameters are extracted from the query string and then used in the rewritten URL:

<rule name="Query String Rewrite">
  <match url="page\.asp$" />
  <conditions>
    <add input="{QUERY_STRING}" pattern="p1=(\d+)" />
    <add input="##{C:1}##_{QUERY_STRING}" pattern="##([^#]+)##_.*p2=(\d+)" />
  </conditions>
  <action type="rewrite" url="newpage.aspx?param1={C:1}&amp;amp;param2={C:2}" appendQueryString="false"/>
 </rule>

With this rule, when request is made to page.asp?p2=321&p1=123, it will be rewritten to newpage.aspx?param1=123&param2=321. Parameters p1 and p2 can be in any order in the original query string.

Avoid Rewriting of Requests for ASP.NET Web Resources

ASP.NET-based web applications very often make requests to WebResources.axd file to retrieve assembly resources and serve them to the Web browser. There is no such file exists on the server because ASP.NET generates the content dynamically when WebResources.axd is requested. So if you have a URL rewrite rule that does rewriting or redirection only if requested URL corresponds to a file or a folder on a web server’s file system, that rule may accidentally rewrite requests made to WebResources.axd and thus break your application. This problem can be easily prevented if you add one extra condition to the rewrite rule:

<rule name="RewriteUserFriendlyURL1" stopProcessing="true">
  <match url="^([^/]+)/?$" />
  <conditions>
    <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
    <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
    <!--  The following condition prevents rule from rewriting requests to .axd files -->
    <add input="{URL}" negate="true" pattern="\.axd$" />
  </conditions>
  <action type="Rewrite" url="article.aspx?p={R:1}" />
 </rule>

How To Clear All Textboxes in ASP.NET asp.net

private void Button1_Click(object sender, System.EventArgs e)
 {
Control myForm = Page.FindControl("Form1″);

foreach (Control ctl in myForm.Controls)
 {
if (ctl.GetType().ToString().Equals("System.Web.UI.WebControls.TextBox"))
 {
 ((TextBox)ctl).Text = "";
 }
 }
 }

How To Prevent Caching of web form in ASP.NET

private void Page_Load(object sender, System.EventArgs e)
 {
if(!Page.IsPostBack)
 {
 Response.Cache.SetCacheability(HttpCacheability.NoCache);
 Response.Cache.SetAllowResponseInBrowserHistory(false);
 }
 }

How To Refresh aspx Page at Regular Interval

using HTML/Javascript >
 meta content="10" http-equiv="refresh" />
 Using .NET
 Response.AppendHeader("Refresh", "10;URL=Nextpage.aspx");

Retrieve Details of the Row being Deleted in GridView

The ID of the row being deleted must be in the GridView.DataKeyNames collection.

C#
protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
 {
int ID = (int)GridView1.DataKeys[e.RowIndex].Value;
// Query the database and get the values based on the ID
}

VB.NET
Protected Sub GridView1_RowDeleting(ByVal sender As Object, ByVal e As GridViewDeleteEventArgs)
Dim ID As Integer = CInt(GridView1.DataKeys(e.RowIndex).Value)
' Query the database and get the values based on the ID
 End Sub

 Tip 7: Cancelling Update and Delete in a GridView
 RowUpdating - Occurs when a row's Update button is clicked, but before the GridView control
 updates the row.
 RowDeleting – Occurs when a row's Delete button is clicked, but before the GridView control
 deletes the row.

C#
protected void gvDetail_RowUpdating(object sender, GridViewUpdateEventArgs e)
 {
 e.Cancel = true;
 }
void GridView1_RowDeleting(Object sender, GridViewDeleteEventArgs e)
 {
// Check for a condition and cancel the delete 
// There should    be atleast one row left in the GridView
if (GridView1.Rows.Count <= 1)
 {
 e.Cancel = true;
 }
 }

VB.NET
Protected Sub gvDetail_RowUpdating(ByVal sender As Object, ByVal e As GridViewUpdateEventArgs)
e.Cancel = True
End Sub
Private Sub GridView1_RowDeleting(ByVal sender As Object, ByVal e As GridViewDeleteEventArgs)
' Check for a condition and cancel the delete ' There should be
    atleast one row left in the GridView
If GridView1.Rows.Count <= 1 Then
 e.Cancel = True
End If End Sub

Paging and Sorting in GridView without using DataSource control

C#
 <asp:gridview ID="gridView" runat="server" OnPageIndexChanging="gridView_PageIndexChanging"
 OnSorting="gridView_Sorting">
 </asp:gridview>
 private string ConvertSortDirectionToSql(SortDirection sortDireciton)
 {
 string newSortDirection = String.Empty;
 switch (sortDirection)
 {
 case SortDirection.Ascending:
 newSortDirection = "ASC";
 break;
 case SortDirection.Descending:
 newSortDirection = "DESC";
 break;
 }
 return newSortDirection
 }
 protected void gridView_PageIndexChanging(object sender, GridViewPageEventArgs e)
 {
 gridView.PageIndex = e.NewPageIndex;
 gridView.DataBind();
 }
 protected void gridView_Sorting(object sender, GridViewSortEventArgs e)
 {
 DataTable dataTable = gridView.DataSource as DataTable;
if (dataTable != null)
 {
 DataView dataView = new DataView(dataTable);
 dataView.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
 gridView.DataSource = dataView;
 gridView.DataBind();
 }
 }

VB.NET
Private Function ConvertSortDirectionToSql(ByVal sortDireciton As SortDirection) As String
Dim newSortDirection As String = String.Empty

Select Case sortDirection
Case SortDirection.Ascending
 newSortDirection = "ASC"

Case SortDirection.Descending
 newSortDirection = "DESC"
End Select

Return newSortDirection
End Function

Protected Sub gridView_PageIndexChanging(ByVal
sender As Object, ByVal e As GridViewPageEventArgs)
 gridView.PageIndex = e.NewPageIndex
 gridView.DataBind()
End Sub

Protected Sub gridView_Sorting(ByVal sender As Object, ByVal e As GridViewSortEventArgs)
Dim dataTable As DataTable = TryCast(gridView.DataSource, DataTable)

If Not dataTable Is Nothing Then
Dim dataView As
   
    DataView = New DataView(dataTable)
 dataView.Sort = e.SortExpression & " " & ConvertSortDirectionToSql(e.SortDirection)

 gridView.DataSource = dataView
 gridView.DataBind()
End If End Sub

Export GridView To Excel

C#protected void Button1_Click(object sender,EventArgs e) {Response.AddHeader("content-disposition","attachment;filename=FileName.xls");Response.Charset = String.Empty;Response.ContentType = "application/vnd.xls"; System.IO.StringWriter sw = new System.IO.StringWriter();System.Web.UI.HtmlTextWriter hw =new HtmlTextWriter(sw); GridView1.RenderControl(hw);Response.Write(sw.ToString());Response.End();}

VB.NET
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
 Response.AddHeader("content-disposition", "attachment;filename=FileName.xls")
 Response.Charset = String.Empty
 Response.ContentType = "application/vnd.xls"
 Dim sw As System.IO.StringWriter = New System.IO.StringWriter()
 Dim hw As System.Web.UI.HtmlTextWriter = New HtmlTextWriter(sw)
 GridView1.RenderControl(hw)
 Response.Write(sw.ToString())
 Response.End()
End Sub

Request.Form - get values for fields having the same name

Problem
You know it’s possible to have controls with the same name on one page. In this case Request.Form["txtSomeText"] returns the values form all 5 textboxes comma separted. (For example: text1,text2, text3.text4, text5). Example:

.....

          <input type="text" name="txtSomeText" />
          <input type="text" name="txtSomeText" />
          <input type="text" name="txtSomeText" />
          <input type="text" name="txtSomeText" />
          <input type="text" name="txtSomeText" />

          .......

The question iin this case is "How to get the values for each textbox?".
You can say "I’ll split the values…" but it’s not a good solution. What if one of the values is "text,text,text"? I spent a lot of time splitting strings and searching for workaround of "comma values" (a,b,c) until I found the solution. Here it is.. Solution:
It’s simple: Request.Form returns NameValueCollection. GetValues is a NameValueCollection class method which gives us the requested result. Request.Form.GetValues("txtSomeText") returns a string array with all the values.

Operator ===

Have you ever used the strict equal operator? I learned about it few days ago…
Below is a quick explanation of its behavior: "The strict equal to operator returns true if both operands are equal (and of the same type). It doesn’t perform any data type conversion, so an expression like 1 === true returns false and 1 === "1″ also returns false, because this operator checks for the type of the operands. 1 is a numerical value and "1″ is a string value; their types are different."

Hide div and the white space it occupies

Most of the developers will say "I can use javascript and CSS ‘visibility’ property to do that", but shortly after that they’ll realize that this is not enough. This solution will hide the div tag content, but the space it occupies will stay. You can reproduce this behavior using the code below:

if (objDiv.style.visibility == 'visible' ||
            objDiv.style.visibility == '')
            {
            objDiv.style.visibility = 'hidden';
            }
else
            {
            objDiv.style.visibility = 'visible';
            }

where objDiv is the div object which you’re trying to hide. Solution It’s simple - initialize "display" property in addition. So the above code will look like:

if (objDiv.style.visibility == 'visible' ||
            objDiv.style.visibility == '')
            {
            objDiv.style.visibility = 'hidden';
            objDiv.style.display = 'none';
            }
else
            {
            objDiv.style.visibility = 'visible';
            objDiv.style.display = 'block';
            }

Cookie is lost when browser is closed Task
When user visits a site for the first time a disclaimer page must be displayed. Once the user agree with it a cookie value is changed to "true" and the next time the user opens the site the disclaimer is not displayed. Problem
The cookie is lost when the browser is closed if you change cookie value. Research
Below is some example code that I used to investigate the problem: Open Visual Studio
Create new web site
Copy and paste the following code to the Page_Load method of defaut.aspx.cs file:

if (Request.Cookies["test"] == null)
  {
  HttpCookie cookieDisclaimer = new HttpCookie("test", "cookie test");
  cookieDisclaimer.Expires = DateTime.MaxValue; // the cookie never expires
  Response.Cookies.Add(cookieDisclaimer);

  Response.Write("cookie added");
  }
else
  {
  // NOTE: We'll add some lines here later
  Response.Write(Request.Cookies["test"].Value);
  }

Buld the website and open in a browser
The first time the browser opens the cookie is created. Click F5 several times and you’ll see cookie value displayed.
Close the browser, open it again and navigate to the website URL. You’ll see directly the the cookie value which means that the cookie exists.

Now let’s update the code, so cookie value is changed.
Add the following code below "NOTE: We’ll add some lines here later":

Response.Cookies["test"].Value = "cookie test";

Execute the steps described above and you’ll see that every time you open a browser the cookie is created. So the cookie expires when the browser is closed. According to me this is not the correct cookie behaviour. Correct me if I’m wrong Solution
The solution is simple: everytime you change the cookie value, you need to set cookie expiration date too. So adding the following code after "NOTE: We’ll add some lines here later" fix the problem:

Response.Cookies["test"].Value = "cookie test";
      Response.Cookies["test"].Expires = DateTime.MaxValue;

I hope the solution above is useful. How To Define Mozilla Specific CSS Today I found a great approach for defining Mozilla specific styles without using Mozilla CSS extentions. The only thing needed is to put all Mozilla specific CSS definitions in a "@-moz-document" block and specify the url, url-prefix or domain to which pages the styles have to be applied:

@-moz-document url(http://www.w3.org/),
      url-prefix(http://www.w3.org/Style/),
      domain(mozilla.org)
      {
/* CSS rules here apply to: + The page "http://www.w3.org/".
    + Any page whose URL begins with "http://www.w3.org/Style/" + Any page
    whose URL's host is "mozilla.org" or ends with ".mozilla.org"
    */ 
      body { ... }
      }

Browser compatibility
Available since Mozilla 1.8 / Firefox 1.5.

DateDiff Function in C#

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication2
        {
public enum DateInterval {
        Year,
        Month,
        Weekday,
        Day,
        Hour,
        Minute,
        Second
        }

class Program {
        static void Main(string[] args)
        {
        DateTime dt1 = new DateTime(1994, 12, 12);
        DateTime dt2 = new DateTime(1994, 12, 12);
        long date = DateDiff(DateInterval.Day, dt1, dt2);
        Console.Write(date);

        Console.ReadLine();
        }

public static long DateDiff(DateInterval interval, DateTime date1, DateTime date2)
        {

TimeSpan ts = ts = date2 - date1;

        switch (interval)
        {
        case DateInterval.Year:
return date2.Year - date1.Year;
        case DateInterval.Month:
return (date2.Month - date1.Month) + (12 * (date2.Year - date1.Year));
        case DateInterval.Weekday:
return Fix(ts.TotalDays) / 7;
        case DateInterval.Day:
return Fix(ts.TotalDays);
        case DateInterval.Hour:
return Fix(ts.TotalHours);
        case DateInterval.Minute:
return Fix(ts.TotalMinutes);
        default:
return Fix(ts.TotalSeconds);
        }
        }

private static long Fix(double Number)
        {
if (Number >= 0)
        {
return (long)Math.Floor(Number);
        }
return (long)Math.Ceiling(Number);
        }
        }
        }

change some text before it is sent to the client

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="InterceptHtml.aspx.cs"
 Inherits="InterceptHtml" %> 
          
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0
        Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
        <head runat="server">
        <title>change text</title>
        </head>
        <body>
        <form id="form1″ runat="server">
        <div>
        Hello World!
        <br />
        Hi
        </div>
</form> </body> </html>

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Text;
using System.IO;
public partial class InterceptHtml : System.Web.UI.Page
        {
        protected void Page_Load(object sender, EventArgs e)
        {
        Response.Filter = new ReplaceHTML(Response.Filter);
        }
 /// <summary> /// Second Method!!!!!!!
    overide the Render Method. /// </summary>  /// <param
        name="writer"></param>
protected override void Render(HtmlTextWriter writer)
        {

StringWriter output = new StringWriter();
        base.Render(new HtmlTextWriter(output));
        writer.Write(output.ToString().Replace("Hi", "Welcome 
       
        to faith\">www.myfaithsolution.com</a>"));
        }
        }

II nd Method

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
// To intercept and get a reference to the HTML, we nowneed to
    create a // class to inherit System.IO.Stream. So, create a new class in
public class ReplaceHTML : System.IO.Stream
        {
private System.IO.Stream Base;
public ReplaceHTML(System.IO.Stream ResponseStream)
        {
if (ResponseStream == null)
throw new ArgumentNullException("ResponseStream");
        this.Base = ResponseStream;
        }
public override
    int Read(byte[] buffer, int offset,
           
            int count)
        {
return this.Base.Read(buffer, offset, count);
        }
public override void SetLength(long value)
        {
        }
public override void Write(byte[] buffer, int offset, int count)
        {
// GET HTML code
        string HTML = System.Text.Encoding.UTF8.GetString(buffer, offset, count);

// Replace the text with something
   
    else 
        HTML = HTML.Replace("Hello World!", "I’ve
    replaced the Hello World example!");

// Send output buffer = System.Text.Encoding.UTF8.GetBytes(HTML);
        this.Base.Write(buffer, 0, buffer.Length);
        }

public override bool CanRead
        {
get { throw
    new Exception("The method or 
           
            operation is not
        implemented."); }
        }

public override bool CanSeek
        {
get { throw
    new Exception("The method or 
           
            operation is not
        implemented."); }
        }

public override bool CanWrite
        {
get { throw
    new Exception("The method or 
           
            operation is not
        implemented."); }
        }

public override void Flush()
        {
        HttpContext.Current.Response.Flush();

        }

public override long Length
        {
get { throw
    new Exception("The method or 
           
            operation is not
        implemented."); }
        }

public override long Position
{
get
{
throw new Exception("The method or operation 
           
            is not implemented.");
        }
set
{
throw new Exception("The method or operation 
           
            is not implemented.");
        }
        }

public override long Seek(long offset, System.IO.SeekOrigin origin)
        {
throw new Exception("The method or operation not implimented");
        }
        }

How To Add Please Wait message to a Button

<%@Page Language="C#" AutoEventWireup="true"
      
       CodeFile="PleaseWaitButton.aspx.cs"
 Inherits="PleaseWaitButton"%>
<!DOCTYPE
   
    html PUBLIC 
        "-//W3C//DTD XHTML 1.0

Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml"> <head
 
  runat="server"> <title>Please Wait message..
         
          </title>
         
          </head>
         
          <body>
         
          <form id="form1″ runat="server"> <div> <div> <asp:Button
ID="Button1″ 
       
        runat="server" Text="Button"
      
       /> </div> </div> </form> </body> </html>

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial
    class PleaseWaitButton : System.Web.UI.Page {
protected void
Button1_Click(object sender, System.EventArgs e)
        {
System.Threading.Thread.Sleep(5000);
ClientScript.RegisterClientScriptBlock(this.GetType(), "reset",
"document.getElementById(’" + Button1.ClientID + "‘).disabled=false;", true);

protected void Page_Load(object sender, System.EventArgs e){
        System.Threading.Thread.Sleep(5000);
        Button1.Attributes.Add("onclick", ClientScript.GetPostBackEventReference(Button1, "") + ";
        this.value=’Please wait…’;this.disabled = true;");
        }
        }

CheckBox OnClick Hide/Show HTML Table

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="HideShow.aspx.cs" Inherits="HideShow"%> 
        <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<script type="text/javascript">
function ShowHide(obj)
        {
if(!obj.checked) {
        document.getElementById(‘tbl_QuestionTags_Software’).style.display = ‘none’;
        document.getElementById(‘tbl_QuestionTags_Software’).style.visibility="hidden";
        }
else {
        document.getElementById(‘tbl_QuestionTags_Software’).style.display = ";
        document.getElementById(‘tbl_QuestionTags_Software’).style.visibility ="visible";
        }
        }
</script>

<title>Untitled Page</title>
</head> <body>
<form id="form1″ runat="server">
<div>
<asp:CheckBox ID="chk_QuestionTags_Software" runat="server" CssClass="text" Text="Software"
onclick="ShowHide(chk_QuestionTags_Software)" />
<table id="tbl_QuestionTags_Software" border="1″ bordercolor="red" cellpadding="0″
cellspacing="0″ style="width: 100%">
        <tr> <td> Test1</td> <td> Test1</td>
    <td> Test1</td> <td> Test1</td> <td> Test1</td>
    </tr> </table> </div> </form> </body>
        </html>

How To Validate Checkboxlist control

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ValidateCheckBoxList.aspx.cs"
        Inherits="ValidateCheckBoxList" %>

        <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
        <html xmlns="http://www.w3.org/1999/xhtml">
        <head id="Head1″ runat="server">
        <title>Untitled Page</title>
        </head>
        <body>
        <form id="form1 runat="server">
        <div>
        <asp:CheckBoxList ID="CheckBoxList1 runat="server">
        <asp:ListItem Text="a" Value="b"></asp:ListItem>
        <asp:ListItem Text="a" Value="b"></asp:ListItem>
        </asp:CheckBoxList>
        <asp:CustomValidator ID="CustomValidator1 runat="server" ErrorMessage="CustomValidator"
        OnServerValidate="CustomValidator1_ServerValidate">
        </asp:CustomValidator>
        <asp:Button ID="Button1 runat="server" Text="Validate" /></div>
        </form>
        </body>
        </html>

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class ValidateCheckBoxList : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
        {
        }
protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
        {
int i;
        i = 0;

foreach (ListItem item in CheckBoxList1.Items)
        {
if (item.Selected)
        {
        i = i + 1;

        }
        }
if (i > 1)
        {
        args.IsValid = false;
        CustomValidator1.ErrorMessage = "more than one item is selected!";
        }
else
        {
        args.IsValid = true;
        } }
        }

GridView Inside GridView

 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="DataRelation.aspx.cs"
        Inherits="DataRelation" %> 
        <%@ Import Namespace="System.Data" %>
        <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
        <html xmlns="http://www.w3.org/1999/xhtml">
        <head runat="server">
        <title>Untitled Page</title>
        </head>
        <body>
        <form id="form1″ runat="server">
        <div>
        <asp:GridView ID="GridView1″ runat="server"
        AutoGenerateColumns="False">
        <Columns>
        <asp:BoundField DataField="CompanyName"
        HeaderText="CompanyName" />
        <asp:TemplateField>
        <ItemTemplate>
        <asp:GridView ID="GridView2″
        DataSource=’<%#((DataRowView)Container.DataItem).CreateChildView("ParentChild") %>’
runat="server" AutoGenerateColumns="False">
        <Columns>
        <asp:BoundField DataField="Dept"
        HeaderText="Department" />
        <asp:BoundField DataField="name"
        HeaderText="Name" />
        </Columns>
        </asp:GridView>
        </ItemTemplate>
        </asp:TemplateField>
        </Columns>
        </asp:GridView>
        </div>
        </form>
        </body>
        </html>

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class DataRelation : System.Web.UI.Page {
protected void Page_Load(object sender, EventArgs e)
        {
if (!IsPostBack)
        {
        GridView1.DataSource = CreateDS().Tables["Company"];
        GridView1.DataBind();
        }}
        private DataSet CreateDS()
        {
DataSet ds;
if (Session["DataList_ParentChild"] == null)
        {
        ds = new DataSet();
DataTable dt = new DataTable("Company");
DataRow dr;
        dt.Columns.Add(new DataColumn("ID", typeof(Int32)));
        dt.Columns.Add(new DataColumn("CompanyID", typeof(Int32)));
        dt.Columns.Add(new DataColumn("Name", typeof(string)));
        dt.Columns.Add(new DataColumn("Dept", typeof(string)));
        for (int i = 1; i < 10; i++)
        {
        dr = dt.NewRow();
        dr[0] = i;
        dr[1] = "Company " + i;
        dr[3] = "Manager name";
        dr[4] = "Adminstration";
        dt.Rows.Add(dr);
        }
        ds.Tables.Add(dt);
        DataColumn[] Parent_PKColumns = new DataColumn[1];
        Parent_PKColumns[0] = dt.Columns["ID"];
        dt.PrimaryKey = Parent_PKColumns;
        dt = new DataTable("Employees");
        dt.Columns.Add(new DataColumn("ID", typeof(Int32)));
        dt.Columns.Add(new DataColumn("CompanyID", typeof(Int32)));
        dt.Columns.Add(new DataColumn("Name", typeof(string)));
        dt.Columns.Add(new DataColumn("Dept", typeof(string)));
for (int i = 1; i < 10; i++)
        {
int imax = 0;
if (i % 2 == 0) imax = 5;
else imax = 4;
        for (int y = 2; y < imax; y++) //3 emplyees for each company
{
        dr = dt.NewRow();
        dr[0] = y + i * 5;
        dr[1] = i;
        dr[2] = "Employee # " + dr[0];
        dr[3] = "Dept # " + (y + i);
        dt.Rows.Add(dr);
        }
        }
DataColumn[] Child_PKColumns = new DataColumn[1];
        Child_PKColumns[0] = dt.Columns["ID"];
        dt.PrimaryKey = Child_PKColumns;
        ds.Tables.Add(dt);
DataColumn[] Child_FKColumns = new DataColumn[1];
        Child_FKColumns[0] = dt.Columns["CompanyID"];

        ds.Relations.Add("ParentChild", Parent_PKColumns, Child_FKColumns);
        Session["DataList_ParentChild"] = ds;
        }
else
        {
        ds = (DataSet)Session["DataList_ParentChild"];
        }
return ds;
        }
        }

How To Disabling a button until processing is Complete

Here’s the scenario - let’s say you have an Insert subroutine, called ‘doInsert’.
You want to immediately disable the Submit button, so that the end-user won’t click it
multiple times, therefore, submitting the same data multiple times.

For this, use a regular HTML button, including a Runat="server" and an ‘OnServerClick’
event designation - like this:

<INPUT id="Button1″ onclick="document.form1.Button1.disabled=true;" type="button"
          value="Submit - Insert Data" name="Button1″ runat="server" onserverclick="doInsert">

Then, in the very last line of the ‘doInsert’ subroutine, add this line:
Button1.enabled="True"

How To Generate Random Image Using HttpHandler in ASP.NET

How to construct an image generator used to create a visual security code that helps prevent automated sign ups in your web applications.The text generated is stored in Session to be used for comparison to the user’s input.

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing.Imaging;
 using System.Text;
using System.Web.SessionState;


public class Handler : IHttpHandler, IRequiresSessionState
              {
public void ProcessRequest(HttpContext context)
              {
              context.Response.ContentType = "image/gif";
Bitmap b = new Bitmap(200, 60);
              Graphics g = Graphics.FromImage(b);
              g.FillRectangle(new SolidBrush(Color.White), 0, 0, 200, 60);
span span = new span(spanFamily.GenericSansSerif, 48, spanStyle.Bold,
GraphicsUnit.Pixel);
              Random r = new Random();
              string letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
              string letter;
StringBuilder sb = new StringBuilder();
              for (int x = 0; x < 5; x++)
              {
              letter = letters.Substring(r.Next(0, letters.Length - 1), 1);
              sb.Append(letter);
              g.DrawString(letter, span, new SolidBrush(Color.Black), x * 38, r.Next(0, 15));
              }
Pen linepen = new Pen(new SolidBrush(Color.Black), 2);
for (int x = 0; x < 6; x++)

              g.DrawLine(linepen, new Point(r.Next(0, 199), r.Next(0, 59)),

new Point(r.Next(0, 199), r.Next(0, 59)));

              b.Save(context.Response.OutputStream, ImageFormat.Gif);
              context.Session["image"] = sb;
              context.Response.End();
              }
public bool IsReusable

              {get{
return true;
              }

              }



br

br

br

br
br
br

}
How To Use
<img src="Handler.ashx" alt="Random Image" />

What is Diffrence between Src and Codebehind

You may have noticed that Visual Studio.NET adds an interesting keyword to the Page directive of an ASP.NET web form: CodeBehind. However, you will not find this documented in the .NET documentation for the Page directive. Visual Studio.NET implements CodeBehind by precompiling the base class, then uses the Inherits keyword to refer to that class. The CodeBehind keyword allows the IDE to remember the file containing your base class. However, what if you do not want to precompile your class into an assembly?

According to the .NET documentation, the Src attribute of the Page directive:

Specifies the source file name of the code-behind class to dynamically compile when the page is requested.
Note: RAD designers, such as Visual Studio.NET, do not use this attribute. Instead, they precompile code-behind classes and then use the Inherits attribute.

So, by using the Src attribute to indicate the file, and the Inherits keyword to indicate the class, you can accomplish Codebehind. Here is an example Web Form Inheriting from the HelloWorld class in the HelloWorld.cs file:

<%@ Page Language="C#" Inherits="DotNetCoders.HelloWorld" Src="HelloWorld.cs"  trace="true" %>

  <html>
  <body>
  <asp:Label id="ProgrammersMessage" runat="server" />
  </body>
  </html>As you can see, the differences in the page directives are as follows:Visual Studio.NET
  <%@ Page language="C#" Inherits="DotNetCoders.HelloWorld"
  Codebehind="HelloWorld.aspx.cs" %>
  Inherits keyword

How To Change The color of GridView Row Color by Using Simple Mouse Click

In this article I will demonstrate that how you can change the color of the GridView row by using simple mouse click and change it back to its original color by clicking the row twice.
Take a look at the RowCreated event below to have a better idea:

protected void MyGridView_RowCreated(object sender, GridViewRowEventArgs e)
    {
string rowID = String.Empty;
if (e.Row.RowType == DataControlRowType.DataRow)
    {
    rowID = "row"+e.Row.RowIndex;
    e.Row.Attributes.Add("id","row"+e.Row.RowIndex);
    e.Row.Attributes.Add("onclick","ChangeRowColor(" +"‘" + rowID + "‘" + ")");
    }
    }
    JavaScript Function:
    <script language ="javascript" type="text/javascript">
    document.body.style.cursor = ‘pointer’;
    var oldColor = ";
    function ChangeRowColor(rowID)
    {
    var color = document.getElementById(rowID).style.backgroundColor;
    if(color != ‘yellow’)
    oldColor = color;
    if(color == ‘yellow’)
    document.getElementById(rowID).style.backgroundColor = oldColor;
else document.getElementById(rowID).style.backgroundColor = ‘yellow’;
    }
</script>

The ChangeRowColor function takes in the id of the row and finds the color of the row. Then it checks that if the color is ‘yellow’ which, is the color of the highlight row. If it is not yellow then it simply assigns the color to the public variable oldColor which is used to save the previous color of the GridView row.
If the color is yellow then we get the previous color and assign to the row so that it can come back to its original state.

Aug 16How To Prevents users to go back to the previous pages
Sometimes we are in a situation that we don’t want the user to visit the previous pages. This can be a scenario when the user logs out but uses the back button to navigate to the pages. In this article I will show you some simple ways you can use to prevent user from going back.

Using History(+1) Method:

Let’s say that you have a page called Default.aspx which is the secure page and when you click the button you are redirected to
another page Default2.aspx. Now from Default2.aspx. you don’t want to go back to the Default.aspx.. You can achieve this easily using few lines of code.

Let’s first catch the button click event and send the user to the Default2.aspx page.

protected void Button1_Click(object sender, EventArgs e){

Response.Redirect("Default2.aspx");

}

Now if you press the button you will be redirected to the Default2.aspx page. If you press the back button you will be taken to the Default.aspx page.
Now we will implement the functionality that will prevent the user to go to the Default2.aspx page.

In the Default.aspx html write the following code:

<body onLoad="if(history.length>0)history.go(+1)">

That’s it. It means every time you will go to the Default.aspx page you will be forwarded to the Default2.aspx

Using DataView. RowFilter to remove nulls

I wanted to set a filter on my DataView so rows with a null value (in my case the STATE column) would be filtered out. This is how I did it: [csharp]dv.RowFilter = "IsNull(STATE,'null') <> 'null'";[/csharp]

How To Compare Version Information of Two Executable Modules

You need to programmatically compare the version information of two executable modules. An executable module is a file that contains executable code such as an .exe or .dll file. The ability to compare the version information of two executable modules can be very useful to an application in situations such as:

Trying to determine if it has all of the "right" pieces present to execute

Deciding on an assembly to dynamically load through reflection

Looking for the newest version of a file or .dll from many files spread out in the local filesystem or on a network

Use the CompareFileVersions method to compare executable module version information. This method accepts two filenames, including their paths, as parameters. The version information of each module is retrieved and compared. This file returns a FileComparison enumeration, defined as follows:

public enum FileComparison
          {
          Same = 0,
          Newer = 1, // File1 is newer than File2
          Older = 2, // File1 is older than File2
          Error = 3
          }
The code for the CompareFileVersions method is shown below
    with proper commenting.
          public static FileComparison CompareFileVersions(string file1, string file2)
          {
          FileComparison retValue = FileComparison.Error;
// Do both files exist? if (!File.Exists(file1))
          {
          Console.WriteLine(file1 + " does not exist");
          }
else if (!File.Exists(file2))
          {
          Console.WriteLine(file2 + " does not exist");
          }
else
{
// Get the version information. FileVersionInfo file1Version = FileVersionInfo.GetVersionInfo(file1);
          FileVersionInfo file2Version = FileVersionInfo.GetVersionInfo(file2);


          // Check major.

if (file1Version.FileMajorPart > file2Version.FileMajorPart)
          {
          Console.WriteLine(file1 + " is a newer version");
          retValue = FileComparison.Newer;
          }
else if (file1Version.FileMajorPart <>
          {
          Console.WriteLine(file2 + " is a newer version");
          retValue = FileComparison.Older;
          }
else // Major version is equal,
    check next… {
          // Check minor.
if (file1Version.FileMinorPart > file2Version.FileMinorPart)
          {
          Console.WriteLine(file1 + " is a newer version");
          retValue = FileComparison.Newer;
          }
else if (file1Version.FileMinorPart <>
          {
          Console.WriteLine(file2 + " is a newer version");
          retValue = FileComparison.Older;
          }
else // Minor version is equal, check next…
          {
          // Check build.
if (file1Version.FileBuildPart > file2Version.FileBuildPart)
          {
          Console.WriteLine(file1 + " is a newer version");
          retValue = FileComparison.Newer;

          }
else if (file1Version.FileBuildPart <>
          {
          Console.WriteLine(file2 + " is a newer version");
          retValue = FileComparison.Older;
          }
else // Build version is equal, check next…
          {
          // Check private.
if (file1Version.FilePrivatePart >
          file2Version.FilePrivatePart)
          {
          Console.WriteLine(file1 + " is a newer version");
          retValue = FileComparison.Newer;
          }
else if (file1Version.FilePrivatePart <

          file2Version.FilePrivatePart)
          {
          Console.WriteLine(file2 + " is a newer version");
          retValue = FileComparison.Older;
          }
else
{
// Identical versions Console.WriteLine("The files have the same version");
          retValue = FileComparison.Same;
          }}}
          }
          }
          return retValue;
          }

Not all executable modules have version information. If you load a module with no version information using the FileVersionInfo class, you will not provoke an exception, nor will you get null back for the object reference. Instead, you will get a valid FileVersionInfo object with all data members in their initial state (which is null for .NET objects).

Assemblies actually have two sets of version information: the version information available in the assembly manifest and the PE (Portable Executable) file version information. FileVersionInfo reads the assembly manifest version information.

The first action this method takes is to determine whether the two files passed in to the file1 and file2 parameters actually exist. If so, the static GetVersionInfo method of the FileVersionInfo class is called to get version information for the two files.

The CompareFileVersions method attempts to compare each portion of the file’s version number using the following properties of the FileVersionInfo object returned by GetVersionInfo:

FileMajorPart

The first 2 bytes of the version number

FileMinorPart

The second 2 bytes of the version number

FileBuildPart

The third 2 bytes of the version number

FilePrivatePart

The final 2 bytes of the version number

The full version number is comprised of these four parts, making up an 8-byte number representing the file’s version number.

The CompareFileVersions method first compares the FileMajorPart version information of the two files. If these are equal, the FileMinorPart version information of the two files is compared. This continues through the FileBuildPart and finally the FilePrivatePart version information values? If all four parts are equal, the files are considered to have the same version number. If either file is found to have a higher number than the other file, it is considered to be the latest version.

How To Get Information for All Drives on a System

Your application needs to know if a drive (HDD, CD drive, DVD drive, etc.) is available and ready to be written to and/or read from. Additionally, it would be nice to know if you have enough available free space on the drive to write information to.

Use the various properties in the DriveInfo class as shown here:

public static void DisplayAllDriveInfo()
              {
              foreach (DriveInfo drive in DriveInfo.GetDrives())
              {
if (drive.IsReady)
              {
              Console.WriteLine("Drive " + drive.Name + " is ready.");
              Console.WriteLine("AvailableFreeSpace: " + drive.AvailableFreeSpace);
              Console.WriteLine("DriveFormat: " + drive.DriveFormat);
              Console.WriteLine("DriveType: " + drive.DriveType);
              Console.WriteLine("Name: " + drive.Name);
              Console.WriteLine("RootDirectory.FullName: " +drive.RootDirectory.FullName);
              Console.WriteLine("TotalFreeSpace: " + drive.TotalFreeSpace);
              Console.WriteLine("TotalSize: " + drive.TotalSize);
              Console.WriteLine("VolumeLabel: " + drive.VolumeLabel);
              }
else
              {
              Console.WriteLine("Drive " + drive.Name + " is not ready.");

              }}}

Of particular interest are the IsReady and AvailableFreeSpace properties.The IsReady property determines if the drive is ready to be queried, written to, or read from.The AvailableFreeSpace property returns the free space on that drive in bytes.

How To Convert an IP Address To Hostname

You have an IP address that you need to resolve into a hostname.se the Dns.GetHostEntry method to get the hostname for an IP address. In the following code, an IP address is resolved, and the hostname is accessible from the HostName property of the IPHostEntry:

 using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
// Use the Dns class to resolve the address.
   


IPHostEntry iphost = Dns.GetHostEntry("127.0.0.1";
// HostName property holds the hostname. string hostName = iphost.HostName;// Print out name.
                  Console.WriteLine(hostName);

This article has been posted at new york dating site architect providing free online dating service.
Surprises never cease so as the growth of our online dating site, which has been on rampage.
Aug 12How To Convert a Hostname to an IP Address
You have a string representation of a host (such as www.google.com ), and you need to obtain the IP address from this hostname.

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
namespace ConsoleApplication1
                    {
                    class Program{
static void Main(string[] args){
                    Console.WriteLine(HostName2IP("www.google.com"));

Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}Cbr
}Console.Read();
}
public static string HostName2IP(string hostname){
// Resolve the hostname into an iphost entry using the
    Dns class.
IPHostEntry iphost = System.Net.Dns.GetHostEntry(hostname);
// Get all of the possible IP addresses for this hostname.
IPAddress[] addresses = iphost.AddressList;

bbr style="color: #009900"br style="color: #009900"bbr style="color: #009900"br style="color: #009900"bbr style="color: #009900"br style="color: #009900"bbr style="color: #009900"br style="color: #009900"bbr style="color: #009900"br style="color: #009900"bbr style="color: #009900"br style="color: 
#009900"bbr style="color: #009900"br style="color: #009900"bbr style="color: #009900"br style="color: #009900"
// Make a text representation of the list. StringBuilder addressList = new StringBuilder();
// Get each IP address. foreach (IPAddress address in addresses)
{// Append it to the list. addressList.AppendFormat("IP Address: {0};", address.ToString());
}
return addressList.ToString();
}}}

How to locate control nested inside of another control

Finding controls within a Page’s control hierarchy can be hard to find but if you know how the controls are nested you can use the lesser known "$" shortcut to find controls without having to write recursive code. The following example shows how to use the DefaultFocus property to set the focus on a textbox that is nested inside of a FormView control. Notice that the "$" is used to delimit the nesting:

<form id="Form2" runat="server" defaultfocus="formVw$txtName">
  <div>
  <asp:formview ID="formVw" runat="server">
  <itemtemplate>
  Name: Text='<%# Eval("FirstName") + " " + Eval("LastName") %>' />
  </itemtemplate>
  </asp:formview>
  </div>
  </form>

This little trick can also be used on the server-side when
    calling FindControl(): TextBox tb = this.FindControl("form1$formVw$txtName") as TextBox; if (tb != null)
  { //Access TextBox control }

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class PleaseWaitButton : System.Web.UI.Page
  {
protected void Button1_Click(object sender, System.EventArgs e)
  {
System.Threading.Thread.Sleep(5000);
  ClientScript.RegisterClientScriptBlock(this.GetType(), "reset", "document.getElementById(’"
  + Button1.ClientID + "‘).disabled=false;", true);
  }
protected void Page_Load(object sender, System.EventArgs e)
  {
  System.Threading.Thread.Sleep(5000);
  Button1.Attributes.Add("onclick", ClientScript.GetPostBackEventReference(Button1, "") + ";
       

        this.value=’Please wait…’;this.disabled = true;");
  }
  }

Adding Google Search To Your Program using ASP.NET asp.net

Setting up 1. Download the Google API from http://www.google.com/apis/ and then follow the instructions to acquire a search key.
2. Get the >NET SDK if you don’t have it already and don’t have VS.NET
3. You can use the packaged Google api web service proxy or generate your own proxy class using the wsdl.exe util that comes packaged with ASP.NET SDK.
4. Compile the proxy class using a command something like vbc /t:library /out:Google.dll Google.vb /r:System.web.dll /r:System.web.Services.dll /r:System.data.dll /r:system.dll /r:System.xml.dll

Note that for this we renamed the generated proxy class file to Google.vb mostly for clarity.
5. Next copy the generated Google.dll into the bin folder of your web app.
6. Add an entry in Web.config to hold the google key you received — in ours we put it in the appsettings section of web.config and called the key googlekey. Alternatively, you can hard-code the key in the search page.

7. Write the search page - a sample of our code is shown in the next section

public void GoogleSearch()
      {
      com.google.api.GoogleSearchService objSearch = new com.google.api.GoogleSearchService();


br

br

br

br
br
br

// Invoke the search method com.google.api.GoogleSearchResult objResults =
objSearch.doGoogleSearch("license-key-goes-here", "India", 0, 10, false, "", false, "", "", ""
);
// Loop through result elements short shtCount;
for (shtCount = 0; shtCount <= objResults.endIndex - 1; shtCount++){
MessageBox.Show(objResults.resultElements(shtCount).title +
" - " + objResults.resultElements(shtCount).URL); } }
Getting and Setting the Application Version Number

In the AssemblyInfo.cs file for each project, you have the opportunity to set the version number of the Assembly.
A version number is designed by four number: major.minor.build.revision. The default is 1.0.* If left to this, third number (build) will be set to the number of days since January 1, 2000 local time. The fourth number (revision) will be set to the number of seconds since midnight local time. This is useful since it will always increment every time you build the assembly, unless you are working at 2 a.m. on the last Sunday in October in most places in the United States. However, in a production environment, you may want to control those numbers manually.
In which case, you could set the version to something like 1.3.25.31.

Note that .NET considers changes to the major or minor version to be significant changes, but changes to the build and revision are not.
So if you have a reference to an Assembly in the Global Assembly Cache and the major or minor version changes, the new version is considered incompatible with the old version and the previous version will still be linked to. To retrieve the version number from the assembly in your code, you use can do this:

String strVersion = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version.ToString();
To retrieve the version number from the assembly that is calling your assembly, you can use this:
String strVersion = System.Reflection.Assembly.GetCallingAssembly().GetName().Version();

Seeing What is in the ViewState in ASP.NET Web Forms asp.net
Have you ever wondered what is actually encoded in the __VIEWSTATE hidden variable on your Web Forms? It’s actually a base64 serialized encoding of a datatype called a Triplet,
that has other objects nested within it. I threw together a small class that has a single static method that will write the viewstate to a file. It indents to see the hierarchy. It also deserializes the viewstate into a Triplet object that you can view in the debugger.
This code is only for debugging, and should not be left in the shipping application.
Call the method in the Page_Load event of your Web Form, like this:
DebugViewState.SeeViewState(Request.Form["__VIEWSTATE"], @"c:\temp\viewstate.txt");
and include this class in the project:

using System;
using System.Diagnostics;
using System.Web.UI;
  public class DebugViewState
  {
  public static void SeeViewState(string strViewState, string strFilename)
  {
if (strViewState != null)
  {
 Debug.Listeners.Clear();
  System.IO.File.Delete(strFilename);
  Debug.Listeners.Add(new TextWriterTraceListener(strFilename));
  string strViewStateDecoded =
  (new System.Text.UTF8Encoding()).
  GetString(Convert.FromBase64String(strViewState));
  string[] astrDecoded = strViewStateDecoded.Replace("<", "<\n").
  Replace(">", "\n>").Replace(";", ";\n").Split(’\n’);
  Debug.IndentSize = 4;
  foreach (string str in astrDecoded)
if (str.Length > 0)
if (str.EndsWith(@"\<"))
  Debug.Write(str);
else if (str.EndsWith(@"\"))
  Debug.Write(str);
else if (str.EndsWith("<"))
  { Debug.WriteLine(str);
  Debug.Indent(); }
else if (str.StartsWith(">;") || str.StartsWith(">"))
  {
  Debug.Unindent();
 Debug.WriteLine(str);
  }
else if (str.EndsWith(@"\;"))
  Debug.Write(str);
 else Debug.WriteLine(str);
  Debug.Close();
 Debug.Listeners.Clear();
//Get into the debugger after executing this line to see
    how .NET looks //at //the ViewState info. Compare it to the text file produced above.
Triplet trp = (Triplet) ((new LosFormatter()).Deserialize(strViewState));

  } } }

Send the Right error codes in Asp.net asp.net
If you have a broken internal link on your ASP.NET website and follow it, you will see the well known yellow screen of death (YSOD). Not only is it ugly, but it could also tell the visitor more than they should know about your system. The broken link sends a 404 HTTP status code to the client, but instead of providing the visitor with the YSOD, it will be better to use the browsers build-in view for those kinds of errors.
It’s a view visitors know and not an arbitrary YSOD with strange information. Of course, this is only true if you have no custom error HTML page. Keep in mind that custom error aspx pages are not good enough, because if a global ASP.NET exception occurs, then they won’t work either. You can bypass the default YSOD by adding this method to the global.asax.

private void Application_Error(object sender, EventArgs e)
    {
    HttpException ex = Server.GetLastError() as HttpException;
if (ex !=null)
    {
// When a HttpException occurs. Response.StatusCode = ex.GetHttpCode();
 }
else
{
// When any other exception occurs. Response.StatusCode = 500;
    }
    Response.End();
    }

Do Postback With Parameters in javascript asp.net
Whenever you use a Button or LinkButton it is because you want to be able to do a postback when it is clicked. The same could be the case for CheckBox or DropDownList etc. but then you need to set the AutoPostback property to true. It all works very much the same way from a user’s point of view - click or select and the page performs a postback. However, in some cases you want to be able to do a postback from a custom JavaScript function that emulates the click of an e.g. LinkButton. That is very simple to do so, but did you know that you also can send custom information via such a postback? Example The following LinkButton calls the server-side event handler OnSaveClick.

<asp:LinkButton runat="Server" ID="btnSave" Text="Save" OnClick="OnSaveClick" />

This is pretty much standard and no tricks have been used so far. Now we need the JavaScript method that forces the LinkButton to do a postback that calls the server-side method OnSaveClick.

<script type="text/javascript">
function SaveWithParameter(parameter)
      {__doPostBack(’btnSave ‘, parameter)}
/script>

Notice that the function takes a parameter that it sends to the __doPostBack function. All we need to do now is to call the SaveWithParamter function from JavaScript. > SaveWithParameter("Hello world!"); Now the page performs a postback and we can now access the "Hello world!" string that we sent as a parameter from within the OnSaveClick event handler.

protected void OnSaveClick(object sender, EventArgs e)
      {
string parameter = Request[
    "__EVENTARGUMENT"];
      }

What we just did was to perform a postback from a custom JavaScript function and send a parameter to the server-side event handler. It sounds a lot harder than it is, right? > In ASP.NET 2.0 you have to set the EnableEventValidation="false" attribute in the page declaration or in web.config to make it work.

How To Generate Unique numbers and String in C#

The System.Guid is used whenever we need to generate a unique key, but it is very long. That’s in many cases not an issue, but in a web scenario where it is part of the URL we need to use its string representation which is 36 characters long. It clutters up the URL and is just basically ugly. It is not possible to shorten it without loosing some of the uniqueness of the GUID, but we can come a long way if we can accept a 16 character string instead.
We can change the standard GUID string representation: 21726045-e8f7-4b09-abd8-4bcc926e9e28 Into a shorter string: 3c4ebc5f5f2c4edc The following method creates the shorter string and it is actually very unique. An iteration of 10 million didn’t create a duplicate. It uses the uniqueness of a GUID to create the string.

private string GenerateId()
          {
          long i = 1;
          foreach (byte b in Guid.NewGuid().ToByteArray())
          {
          i *= ((int)b + 1);
          }
          return string.Format("{0:x}", i - DateTime.Now.Ticks);
          }

If you instead want numbers instead of a string, you can do that to but then you need to go up to 19 characters. The following method converts a GUID to an Int64.

private long GenerateId()
          {
          byte[] buffer = Guid.NewGuid().ToByteArray();
          return BitConverter.ToInt64(buffer, 0);
          }

The standard GUID is still the best way to ensure the uniqueness even though it isn’t 100% unique.

How To Compress and Decompress Strings in C# asp.net

You need a way to compress the data you write to a file using one of the stream-based classes. In addition, you need a way to decompress the data from this compressed file when you read it back in. Use the System.IO.Compression.DeflateStream or the System.IO.Compression. GZipStream classes to read and write compressed data to a file. The Compress and DeCompress methods shown below demonstrate how to use these classes to compress and expand data on the fly.

using System.IO.Compression;
using System.Text;
using System.IO;

public static string Compress(string text)
              {
byte[] buffer = Encoding.UTF8.GetBytes(text);
MemoryStream ms =new MemoryStream();
using (GZipStream zip =new GZipStream(ms, CompressionMode.Compress, true))
              {
              zip.Write(buffer, 0, buffer.Length);
              }
              ms.Position = 0;
MemoryStream outStream =new MemoryStream();
              byte[] compressed =new byte[ms.Length];
              ms.Read(compressed, 0, compressed.Length);
              byte[] gzBuffer =new byte[compressed.Length + 4];
              System.Buffer.BlockCopy(compressed, 0, gzBuffer, 4, compressed.Length);
              System.Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gzBuffer, 0, 4);
return Convert.ToBase64String (gzBuffer);
              }
public static string Decompress(string compressedText)
              {
              byte[] gzBuffer = Convert.FromBase64String(compressedText);
using (MemoryStream ms =new MemoryStream())
              {
int msgLength = BitConverter.ToInt32(gzBuffer, 0);
              ms.Write(gzBuffer, 4, gzBuffer.Length - 4);
              byte[] buffer =new byte[msgLength];
              ms.Position = 0;
using (GZipStream zip =new GZipStream(ms, CompressionMode.Decompress))
              {
              zip.Read(buffer, 0, buffer.Length);
              }
return Encoding.UTF8.GetString(buffer);
              }
              }

The strings need to be longer than 3-400 characters; otherwise the compression rate is not good enough.

How To do Screen Scraping in C#

public static
       string ScreenScrape(string url)
              {
              System.Net.WebRequest request = System.Net.WebRequest.Create(url);
              // set properties of the request
              using (System.Net.WebResponse response = request.GetResponse())
              {
              using (System.IO.StreamReader reader = new System.IO.StreamReader(response.GetResponseStream()))
              {
              return reader.ReadToEnd();
              }
              }
              }

How To Create Javascript Alert from ASP.NET code behind In Windows Forms it is very easy to pop up a status message by calling
MessageBox?Show("message").
It is that kind of object model we want in ASP.NET for printing out JavaScript alerts.
We want Alert.Show("message") in ASP.NET. I’ve written a static class called Alert with one public method called Show?
The implementation is as simple as can be. Just put the .cs file in the App_Code folder on your website and you instantly have access to the method from all pages and user controls. I’ve written a static class called Alert with one public method called Show.
The implementation is as simple as can be. Just put the .cs file in the App_Code folder on your website and you instantly have access to the method from all pages and user controls.

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
                // A JavaScript alert
                public static class Alert
                {
                ////// Shows a client-side JavaScript alert in the browser.
                ///The message to appear in the alert.
                public static void Show(string message)
                {
                // Cleans the message to allow single quotation marks
                string cleanMessage = message.Replace("‘", "\\’");
                string script = " ";
                // Gets the executing web page
                Page page = HttpContext.Current.CurrentHandler as Page;

                // Checks if the handler is a Page and that the script isn’t already on the Page
if (page != null && !page.ClientScript.IsClientScriptBlockRegistered("alert"))
                {
                page.ClientScript.RegisterClientScriptBlock(typeof(Alert), "alert", script);
                }
                }
                }

How To Use Add a button in you asp.net file and add following code in click event of the button

void btnSave_Click(object sender, EventArgs e)
                {
                try
                {
                SaveSomething();
                Alert.Show("You document has been saved");
                }
                catch (ReadOnlyException)
                {
                Alert.Show("You do not have write permission to this file");
                }
                }

Creating a page method for testing purposes.

Writing a page method is easy. They must be declared as static, and they must be decorated with the [WebMethod] attribute. Beyond that, ASP.NET AJAX takes care of the rest on the server side. This will be our page method for the example:

What about the ScriptManager and EnablePageMethods?

public partial class _Default : Page
{
[WebMethod]
public static string GetDate()
{
return DateTime.Now.ToString();
}
}

Traditionally, one of your first steps when utilizing page methods is to set the ScriptManager’s EnablePageMethods property to true. Luckily, that property is a bit of a misnomer. It doesn’t enable page methods at all , but simply generates an inline JavaScript proxy for all of the appropriate methods in your page’s code-behind. For example, if a ScriptManager is added to the above example’s corresponding Default.aspx and its EnablePageMethods property is set to true, this JavaScript will be injected into the page:

var PageMethods = function() {
PageMethods.initializeBase(this);
this._timeout = 0;
this._userContext = null;
this._succeeded = null;
this._failed = null;
}
PageMethods.prototype = {
_get_path:function() {
var p = this.get_path();
if (p) return p;
else  return PageMethods._staticInstance.get_path();},
                    GetDate:function(succeededCallback, failedCallback, userContext) {
return this._invoke(this._get_path(), 'GetDate',false,{},
                    succeededCallback,failedCallback,userContext); }}
PageMethods.registerClass('PageMethods',Sys.Net.WebServiceProxy);
                    PageMethods._staticInstance = new PageMethods();
                     
// Generic initialization code omitted for brevity.
                     
                    PageMethods.set_path("/jQuery-Page-Method/Default.aspx");
                    PageMethods.GetDate = function(onSuccess,onFailed,userContext) {
PageMethods._staticInstance.GetDate(onSuccess,onFailed,userContext);
}

Don’t worry if you don’t understand this code. You don’t need to understand how it works. Just understand that this JavaScript proxy is what allows you to call page methods via the PageMethods.MethodName syntax. The important takeaway here is that the PageMethods proxy object boils down to a fancy wrapper for a regular ASP.NET service call.

Calling the page method with jQuery instead.

Knowing that a page method is consumed in the same way as a web service, consuming it with jQuery isn’t difficult.Using the jQuery.ajax method, this is all there is to it:

$.ajax({
type: "POST",
                    url: "PageName.aspx/MethodName",
                    data: "{}",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function(msg) {
// Do something interesting here.
}
});

Putting it all together.

Corresponding to the example page method above, here’s our Default.aspx:


           <html>
<head>
<title>Calling a page method with jQuery</title>
<script
   
    type="text/javascript"
   
    src="jquery-1.2.6.min.js"></script>
<script
   
    type="text/javascript"
   
    src="Default.js"></script>
</head>
<body>
<div
   
    id="Result">Click here for the time.</div>
</body>
</html>

As you can see, there’s no ScriptManager required, much less EnablePageMethods. As referenced in Default.aspx, this is Default.js:

$(document).ready(function() {
// Add the page method call as an onclick handler for the
    div.
$("#Result").click(function() {
$.ajax({
type: "POST",
                  url: "Default.aspx/GetDate",
                  data: "{}",
                  contentType: "application/json; charset=utf-8",
                  dataType: "json",
                  success: function(msg) {
// Replace the div's content with the page method's return.
$("#Result").text(msg.d);
}
});
});
});

The end result is that when our result div is clicked, jQuery makes an AJAX call to the GetDate page method and replaces the div’s text with its result.

How do stored procedures work in Access?

Unlike other objects in Access, stored procedures have no interface and cannot be created or run through the Access User Interface. The way to get them into your database is to simply code them. I'll show how that's done in ADO.NET.

When a stored procedure is added to an Access Database, the Jet Engine reworks the stored procedure syntax into a query object. To an Access developer this may sound like unnecessary work to code a query. However, it does have its advantages. Consider an application that has to break out into different versions when maintaining both an Access Database and a SQL Server Database. Using stored procedures will make it easier to write the code for the database tier of the application as the program will change very little between the different versions.

Creating Stored Procedures

To demonstrate, I'll first show how to create the SQL statements to create stored procedures. At the end of the article I'll show the entire code needed to run these statements against the database. Using the Northwind database that comes with Access, four stored procedures will be created. Focusing on the Products table for all of them, let's start off with the easiest one; select all data of each row in the table. To create the stored procedure, execute the following SQL statement against the database:

CREATE PROC procProductsList AS SELECT * FROM Products;

The statement: "CREATE PROC procCustomerList" is the part that actually creates the stored procedure. The part following "AS" can be any valid SQL Statement.

Often in a stored procedure you'll want to pass a value to be used in the query. Consider that you may want to delete a record based on a particular ProductID. The following stored procedure shows how to do just that:

CREATE PROC procProductsDeleteItem(inProductsID LONG)" &
                    "AS DELETE FROM Products WHERE ProductsID = inProductsID;"

On the first line, notice the parenthesis right after the CREATE PROC declaration. There is a parameter defined as a Long value. This is where you add the variable to delete the record in question.

The next two statements show how to create an add and an update stored procedure for the Products table respectively. Note that not all fields are included for the sake of brevity:

 CREATE PROC procProductsAddItem(inProductName VARCHAR(40), " &
                    "inSupplierID LONG, inCategoryID LONG) " &
                    "AS INSERT INTO Products (ProductName, SupplierID, CategoryID) " &
                    "Values (inProductName, inSupplierID, inCategoryID);"
                    "CREATE PROC procProductsUpdateItem(inProductID LONG, " &
                    "        
  inProductName VARCHAR(40)) " &
                    "AS UPDATE Products SET ProductName = inProductName " &
                    "    WHERE ProductID = inProductID;

Notice that a comma separates each parameter when more than one is specified.

Limitations

There are some limitations you may encounter here, especially if you're used to the power of SQL Server.

Output parameters cannot be used.
Don't use the @ character. The @ character is often used in Transact SQL (SQL Server), where it represents a local variable. Access doesn't always convert this character and will sometimes leave it out. This can cause esoteric bugs which can lead to premature hair loss.
Temporary tables are not available in Access.
I suspect many of the options available in Transact SQL are not available in Access as it's not Transact SQL compatible.

Imports System
Imports System.Data
Imports System.Data.OleDb
Module CreateSP
                    Sub Main()
                    ProductsProcs()
                    End Sub
' Products Stored Procs to be added to the db. Sub ProductsProcs()
                    Dim sSQL As String
' procProductsList - Retrieves entire table
                    sSQL = "CREATE PROC procProductsList AS SELECT * FROM Products;"
                    CreateStoredProc(sSQL)
                    ' procProductsDeleteItem - Returns
                    the details (one record) from the
                    ' JobTitle table
                    sSQL = "CREATE PROC procProductsDeleteItem(@ProductID LONG) AS " _
                    & "DELETE FROM Products WHERE ProductID = @ProductID;"
                    CreateStoredProc(sSQL)

                    ' procProductsAddItem - Add one record
                    to the JobTitle table
                    sSQL = "CREATE PROC procProductsAddItem(inProductName VARCHAR(40), " _
                    & "inSupplierID LONG, inCategoryID LONG) AS INSERT INTO " _
                    & "Products (ProductName, SupplierID, CategoryID) Values " _
                    & "(inProductName, inSupplierID, CategoryID);"
                    CreateStoredProc(sSQL)
 ' procProductsUpdateItem - Update
                    one record on the JobTitle table
                    sSQL = "CREATE PROC procProductsUpdateItem(inProductID LONG, " _
                    & "inProductName VARCHAR(40)) AS UPDATE Products SET " _
                    & "ProductName = inProductName WHERE ProductID = inProductID;"
                    CreateStoredProc(sSQL)
                    End Sub
                    ' Execute the creation of Stored Procedures
                    Sub CreateStoredProc(ByVal sSQL As String)
                    Dim con As OleDbConnection
                    Dim cmd As OleDbCommand = New OleDbCommand()
                    Dim da As OleDbDataAdapter
                    ' Change Data Source to the location of Northwind.mdb on your local ' system.
                    Dim sConStr As String = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data " _
                    & "Source=C:\Program Files\Microsoft " & "Office\Office10\Samples\Northwind.mdb"

                    con = New OleDbConnection(sConStr)
                    cmd.Connection = con
                    cmd.CommandText = sSQL
                    con.Open()
                    cmd.ExecuteNonQuery()
                    con.Close()
                    End Sub
                    End Module

How to create a date/time info bar at the top of your page

This shows you how to use the onload event in the body tag to show the current date and time when the user loads the page, nicely formatted as well.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
                    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

                    <html xmlns="http://www.w3.org/1999/xhtml">     

                    <head>
                    <meta http-equiv="content-type" content="text/html;charset=utf-8"/>

                    <title>Javascript</title>

                    <script type="text/javascript">      

                    function initialize() {

                    showDateAndTime();
                    }      
                    function showDateAndTime() {

                    //variables

                    var datCurrentDate = new Date();

                    var strCurrentDate = datCurrentDate.toLocaleString();      

                    //set the text

                    document.getElementById('dateTimeLine').innerHTML = strCurrentDate;      

                    }  

                    </script>     

                    <style type="text/css">

                    .infoBar {

                    font-size: 10pt;

                    color: #333;

                    font-family: verdana;

                    background-color: beige;

                    text-align: right;

                    padding: 2px;

                    font-weight: bold;

                    }
                    </style>
                    </head>    

                    <body onload="initialize()">      

                    <div class="infoBar" id="dateTimeLine"></div>    
                    </body>      </html>

Always Use 'var'

Variables in javascript either have global scope or function scope, and using the 'var' keyword is vital to keeping them straight. When declaring a variable for use either as a global variable or as a function-level variable, always prefix the declaration with the 'var' keyword. The example below highlights the potential problem caused by not doing so.

Problem Caused By Not Using Var

var i=0; // This is good - creates a global variable
                    function test() {
   for (i=0; i<10; i++) {
      alert("Hello World!");
   }
                    }
                    test();
                    alert(i); // The global variable i is now 10!

Since the variable i inside the function was not declared as a function-level variable by using the 'var' keyword, it references the global variable in this example. It is a good idea to always declare global variables using 'var', but it is vital to declare function-scoped variables using 'var'. The two approaches below are functionally identical.

Fixed Function

function test() {
  
   var i=0;
   for (i=0; i<10; i++) {
      alert("Hello World!");
   }
                    }

Fixed Function

function test() {
   for (var i=0; i<10; i++) {
      alert("Hello World!");
   }
                    }

Use Square Bracket Notation

When accessing object properties that are determined at run-time or which contain characters not compatible with dot notation, use square bracket notation. If you are not an experienced javascript programmer, it's not a bad practice to use square bracket notation all the time.

Objects properties in javascript can be accessed primarily in two ways: Dot notation and Square bracket notation.

Dot notation

MyObject.property

Square bracket notation

MyObject["property"]

With dot notation, the property name is hard-coded and cannot be changed at run-time. With bracket notation, the property name is a string which is evaluated to resolve the property name. The string can be hard-coded, or a variable, or even a function call which returns a string property name.

If a property name is being generated at run-time, the bracket notation is required. For example, if you have properties "value1", "value2", and "value3", and want to access the property using a variable i=2:

This Will Work

MyObject["value"+i]

This Will Not

MyObject.value+i

Also, in some server-side environments (PHP, Struts, etc) form field names are appended with [] to denote that the form field should be treated as an array on the server-side. However, referencing a field name containing [] using dot notation will not work because [] is the syntax for reference a javascript array. So, square bracket notation is required.

This Will Work

formref.elements["name[]"]

This Will Not

formref.elements.name[]

The recommendation for using square bracket notation is to always use it when it is required (obviously). Using it when not strictly required is a matter of personal preference and convention. One good rule of thumb is to use dot notation to access standard properties of objects, and square bracket notation to access properties which are defined as objects in the page. So, while document["getElementById"]() is perfectly vaid using square bracket notation, document.getElementById() is the preferred syntax because getElementById is a standard property of the document object as defined in the DOM specifications. Mixing the use of dot and square bracket notation makes it clear which properties are standard and which are names defined by the content:

document.forms["myformname"].elements["myinput"].value

Here, the forms property is a standard property of document, while the form name myformname is defined by the page content. Likewise, the elements property and value property are both defined by the specs, but then myinput name is defined in the page. This syntax is very clear and easy to understand and is a recommended convention to follow, but not a strict rule.

Avoid 'eval'

The eval() function in javascript is a way to run arbitrary code at run-time. In almost all cases, eval should never be used. If it exists in your page, there is almost always a more correct way to accomplish what you are doing. For example, eval is often used by programmers who do not know about using Square Bracket Notation.

The rule is, "Eval is evil." Don't use it unless you are an experienced developer and know that your case is an exception.

Reference Forms and Form Elements Correctly

All forms in an HTML form should have a name attribute. For XHTML documents, the name attribute is not required and instead the form tag should have an id attribute and should be referenced using document.getElementById(). Referencing forms using indexes, such as document.forms[0] is a bad practice in almost all cases. Some browsers make the form available as a property of the document itself using its name. This is not reliable and shouldn't be used.

The example below uses square bracket notation and correct object references to show the most fool-proof way of referencing a form input.

Correct Reference To Form Input

document.forms["formname"].elements["inputname"]

Bad Practice

document.formname.inputname

If you will be referencing multiple form elements within a function, it's best to make a reference to the form object first and store it in a variable. This avoids multiple lookups to resolve the form object reference.

var formElements = document.forms["mainForm"].elements;
                    formElements["input1"].value="a";
                    formElements["input2"].value="b";

When validating an input field using onChange or similar event handlers, it is always a good idea to pass a reference to the input element itself into the function. Every input element within a form has a reference to the form object that it is contained in.

<input type="text" name="address" onChange="validate(this)">

                    function validate(input_obj) {
   // Get a reference to the form which contains this element
   var theform = input_obj.form;
   // Now you can check other inputs in the same form without
   // hard-coding a reference to the form itself
   if (theform.elements["city"].value=="") {
      alert("Error");
   }
                    }

By passing a reference to the form element and accessing its form property, you can write a function which does not contain a hard reference to any specific form name on the page. This is a good practice because the function becomes more reusable.

Avoid 'with'

The 'with' statement in javascript inserts an object at the front scope chain, so any property/variable references will first try to be resolved against the object. This is often used as a shortcut to avoid multiple long references.

Example Using with

with (document.forms["mainForm"].elements) {
   input1.value = "junk";
   input2.value = "junk";
                    }

The problem is that the programmer has no way to verify that input1 or input2 are actually being resolved as properties of the form elements array. It is checked first for properties with these names, but if they aren't found then it continues to search up the scope chain. Eventually, it reaches the global object where it tries to treat "input1" and "input2" as global variables and tries to set their "value" properties, which result in an error.

Instead, create a reference to the reused object and use it to resolve references.

Using A Reference Instead

var elements = document.forms["mainForm"].elements;
                    elements.input1.value = "junk";
                    elements.input2.value = "junk";

Use onclick In Anchors Instead Of javascript: Pseudo-Protocol

When you want to trigger javascript code from an anchor <A> tag, the onclick handler should be used rather than the javascript: pseudo-protocol. The javascript code that runs within the onclick handler must return true or false (or an expression than evalues to true or false) back to the tag itself - if it returns true, then the HREF of the anchor will be followed like a normal link. If it returns false, then the HREF will be ignored. This is why "return false;" is often included at the end of the code within an onclick handler.

Correct Syntax

<a href="javascript_required.html" onclick="doSomething(); return false;">go</a>

In this case, the "doSomething()" function (defined by the user somewhere in the page) will be called when the link is clicked, and then false will be returned. The href will never be followed for javascript-enabled browsers. However, if the browser does not have javascript enabled, the javascript_required.html file will be loaded, where you can inform your user that javascript is required. Often, links will just contain href="#" for the sake of simplicity, when you know for sure that your users will have javascript enabled. This practice is discouraged. It's always a good idea to put a local fall-back page that will be loaded for users with javascript disabled.

Sometimes, you want to conditionally follow a link. For example, if a user is navigating away from your form page and you first want to validate that nothing has changed. In this case, your onclick will call a function and it will return a value itself to say whether the link should be followed.

Conditional Link Following

<a href="/" onClick="return validate();">Home</a>

                    function validate() {
    return prompt("Are you sure you want to exit this page?");
                    }

In this case, the validate() function should always return either true or false. True if the user should be allowed to navigate back to the home page, or false if the link should not be followed. This example prompts the user for confirmation, then returns true or false, depending on if the user clicked OK or Cancel.

Below are examples of things NOT to do. If you see code like this in your pages, it is not correct and should be fixed.

What Not To Do

<a href="javascript:doSomething()">link</a>
                    <a href="#" onClick="doSomething()">link</a>
                    <a href="#" onClick="javascript:doSomething();">link</a>
                    <a href="#" onClick="javascript:doSomething(); return false;">link</a>

Use The Unary + Operator To TypeConvert To Number

In javascript, the + operator is used for both addition and concatenation. This can cause problems when adding up form field values, for example, since javascript is a non-typed language. Form field values will be treated as strings, and if you + them together, javascript will treat it as concatenation instead of addition.

Problematic Example

<form name="myform" action="[url]">
                    <input type="text" name="val1" value="1">
                    <input type="text" name="val2" value="2">
                    </form>

                    function total() {
    var theform = document.forms["myform"];
    var total = theform.elements["val1"].value + theform.elements["val2"].value;
    alert(total); // This will alert "12", but what you wanted was 3!
                    }

To fix this problem, Javascript needs a hint to tell it to treat the values as numbers, rather than strings. You can use the unary + operator to convert the string value into a number. Prefixing a variable or expression with + will force it to evaluate as a number, which can then be successfully used in a math operation.

Fixed Example

function total() {
    var theform = document.forms["myform"];
    var total = (+theform.elements["val1"].value) + (+theform.elements["val2"].value);
    alert(total); // This will alert 3
                    }

Avoid document.all

document.all was introduced by Microsoft in IE and is not a standard javascript DOM feature. Although many newer browsers do support it to try to support poorly-written scripts that depend on it, many browsers do not.

There is never a reason to use document.all in javascript except as a fall-back case when other methods are not supported and very early IE support (<5.0) is required. You should never use document.all support as a way to determine if the browser is IE, since other browsers also now support it.

Only Use document.all As A Last Resort

if (document.getElementById) {
    var obj = document.getElementById("myId");
                    }
                    else if (document.all) {
    var obj = document.all("myId");
                    }

Some rules for using document.all are

Always try other standard methods first
Only fall back to using document.all as a last resort
Only use it if you need to support IE versions earlier than 5.0
Always check that it is supported with "if (document.all) { }" around the block where you use it.

Don't Use HTML Comments In Script Blocks

In the ancient days of javascript (1995), some browsers like Netscape 1.0 didn't have any support or knowledge of the script tag. So when javascript was first released, a technique was needed to hide the code from older browsers so they wouldn't show it as text in the page. The 'hack' was to use HTML comments within the script block to hide the code.

Using HTML Comments In Script Is Bad

<script language="javascript">
                    <!--
   // code here
                    //-->
                    </script>

No browsers in common use today are ignorant of the <script> tag, so hiding of javascript source is no longer necessary. In fact, it can be considered harmful for the following reasons:

Within XHTML documents, the source will actually be hidden from all browsers and rendered useless
-- is not allowed within HTML comments, so any decrement operations in script are invalid

Avoid Cluttering The Global Namespace

Global variables and functions are rarely required. Using global may cause naming conflicts between javascript source files and cause code to break. For this reason, it is a good practice to encapsulate functionality within a single global namespace.

There are several ways to accomplish this task, some of which are much more complicated than others. The simplest approach is to create a single global object and assign properties and methods to this object.

Creating A Namespace

var MyLib = {}; // global Object cointainer
          
           MyLib.value = 1;
                    MyLib.increment = function() { MyLib.value++; }
                    MyLib.show = function() { alert(MyLib.value); }
                    MyLib.value=6;
                    MyLib.increment();
                    MyLib.show(); // alerts 7

Namespaces can also be created using Closures, and Private Member Variables can also be simulated in javascript.

Avoid sync "Ajax" calls

When making "Ajax" requests, you may choose either async or sync mode. Async mode runs the request in the background while other browser activities can continue to process. Sync mode will wait for the request to return before continuing.

Requests made with sync mode should be avoided. These requests will cause the browser to lock up for the user until the request returns. In cases where the server is busy and the response takes a while, the user's browser (and maybe OS) will not allow anything else to be done. In cases where a response is never properly received, the browser may continue to block until the request is timed out.

If you think that your situation requires sync mode, it is most likely time to re-think your design. Very few (if any) situations actually require Ajax requests in sync mode.

Use JSON

When storing data structures as plain text or sending/retrieving data structures via Ajax, use JSON instead of XML when possible. JSON (JavaScript Object Notation) is a more compact and efficient data format, and is language-neutral.

Use Correct <script> Tags

The LANGUAGE attribute is deprecated in the <script> tag. The proper way to create a javascript code block is:

<script type="text/javascript">
// code here </script>

How to play an audio file by clicking a link

This code plays two different .wav files depending on which link you click. I tested it in IE6 and Firefox2. Works nicely for short files (e.g. pronouncing words on an educational site) or for intranet applications. Explorer will use Windows Media Player and for Firefox you have to install QuickTime, an easy install.

<html> <head>  
 <script type="text/javascript"> 
function playAudio(audioPathAndFileName)
                    {
document.getElementById("dummyPlayTag").innerHTML=
    '<embed src="' + audioPathAndFileName
                    + '" hidden="true" autostart="true" loop="false">';
 }
      
       </script> </head> <body> 
<a href="#" onclick="playAudio('customAudio/elvis.wav')">Elvis</a>
 <a href="#" onclick="playAudio('customAudio/benFranklin.wav')">Ben Franklin</a>
       
       <span id="dummyPlayTag"></span> </body> 
</html>

Data Grid or Grid View Row Pointer

//Row pointer is used to identify the row which is selected Layout source code:

<asp:GridView ID="GridView1″ runat="server" OnRowCreated="GridView1_RowCreated" AutoGenerateColumns="False" CellPadding="4″
ForeColor="#333333″ GridLines="None" Width="100%">

//VB.NET 2.0 Code Behind:

Protected Sub GridView1_RowCreated(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
Dim rowID As String = String.Empty
If e.Row.RowType = DataControlRowType.DataRow Then
rowID = "row" & e.Row.RowIndex
e.Row.Attributes.Add("id", "row" & e.Row.RowIndex)
e.Row.Attributes.Add("onmouseover", "ChangeRowColor(" & "‘" & rowID & "‘" & ")")
e.Row.Attributes.Add("onmouseout", "ChangeRowColors(" & "‘" & rowID & "‘" & ")")
End If
End Sub

Code to generate a random filename

Here's a short function that will generate
  a random filename   
      Private Function GetRandomFileName() As String   Dim r As New Random()
        Dim i As Integer   Dim strTemp 
 As String ="" For i = 0 To 8 strTemp= strTemp & Chr(Int((26
     
      
         
          * r.NextDouble()) + 65)) Next   Return "c:\\"
      & strTemp & ".bmp" 
 End Function

How do I determine the executing assemblies path?

If your wanting to do this with a Windows Forms application, just use:

Dim path As String = System.IO.Path.GetDirectoryName(Application.ExecutablePath)

Otherwise, you can use:

Dim path As String = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly.Location)

How do I get a list of installed printers?

Use the System.Drawing.Printing.PrinterSettings.InstalledPrinters collection.

How do I translate a Win32 error number into a human readable text message?

You have two ways (using VB.NET) to get a numeric Win32 error message. One is to use the System.Runtime.InteropServices.Marshal.GetLastWin32Error method, while the other is to use the VB.NET specific Err.LastDllError method. Now that you have the numeric representation of the Win32 error, we want to turn it into a text representation, you know, the error message in English.

There's couple of ways to accomplish this. First, we'll explore the Win32 P/Invoke way first. Using this method is the way that the SDK documentation is pointing out. What I've done is wrapped the FormatMessage API call with a VB.NET friendly wrapped version.

Private
 
  Declare Function FormatMessageA
 
  Lib "kernel32" (ByVal
 
  flags As Integer, ByRef source As 
         
          Object, ByVal messageID As
 
  Integer, ByVal languageID
 
  As Integer, 
     
      ByVal buffer As String,
 
  ByVal size As 
     
      Integer, ByRef arguments As
 
  Integer) As 
     
      Integer
 
  Public Shared Function FormatMessage(ByVal
     
      [error] As Integer) As String Const 
 FORMAT_MESSAGE_FROM_SYSTEM As 
    
     Short = &H1000 Const LANG_NEUTRAL
     
      As Short = &H0 Dim buffer As 
 String =  Space(999)
  FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM, 0, [error], LANG_NEUTRAL, buffer,
 999, 0)
  buffer = Replace(Replace(buffer, Chr(13), ""), Chr(10), "")
 
  Return buffer.Substring(0,  buffer.IndexOf(Chr(0)))
End Function

You can then use this method as follows:

Throw New Exception(Marshal.GetLastWin32Error)

A more friendly .NET Framework method is to use the Win32Exception class. Normally when you want to know what the human readable version of the numeric value is, you will probably throw this so the user of your application can see the error. At the very least, so you can easily figure out what is the problem.

Imports System.ComponentModel
Imports System.Runtime.InteropServices

Throw New Win32Exception(Marshal.GetLastWin32Error)

How do I change the color of the text on a tab of the TabControl?

You'll have to set the TabControls DrawMode property to OwnerDrawFixed and draw the text in the TabControls DrawItem procedure.

Private Sub TabControl1_DrawItem(ByVal sender As Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles
    
     TabControl1.DrawItem Dim r As RectangleF = RectangleF.op_Implicit(e.Bounds) Dim ItemBrush As
   New SolidBrush(TabControl1.BackColor)  
Dim sf    As
   New StringFormat
    sf.Alignment = StringAlignment.Center sf.LineAlignment = StringAlignment.Center
If  CBool(e.State
And DrawItemState.Selected)   Then e.Graphics.FillRectangle(ItemBrush, e.Bounds)

 e.Graphics.DrawString(TabControl1.TabPages(e.Index).Text,
        e.span, Brushes.Red, r, sf) Else e.Graphics.DrawString(TabControl1.TabPages(e.Index).Text,
            e.span, Brushes.Blue, r, sf) End  If 
 
  End  Sub

How can I determine the date for next Friday?

Public  
 
  Function GetNextFriday(ByVal
     
      startDate As 
         
          Date) As 
 Date If startDate.DayOfWeek < DayOfWeek.Friday    
     Then   ' If todays day of week is less than
         Friday. ' Add the number of days till next Friday.    
     Return startDate.AddDays(DayOfWeek.Friday - startDate.DayOfWeek) Else  ' Otherwise, subtract
the difference from 7. Return startDate.AddDays(7 - (startDate.DayOfWeek
    -DayOfWeek.Friday)) End If
        End Function

How do I catch errors in 'release' builds, but not while debugging?

Here's the scenario. You want to setup a global error handler (which you should) for your application. This is a good thing. However, it causes a pain when trying to develop within the debugger since now every time an error occurs, your global error handler will capture the error. Here's a solution:

Often times, applications will have a global exception handler in the Main method that catches any exceptions that weren't handled elsewhere. The compiler itself uses a strategy similar to this for out of memory situations -- once we've run out of memory, the compiler's toast, so we throw an exception indicating "out of memory" and then catch it at the top level, giving a nice "out of memory, please restart the compiler" error. (Hopefully none of you have ever seen it.) Anyway, when you're debugging the application it can be convenient to not catch exceptions at the top level so that you immediately break into the debugger when you get a global exception. A simple way to do this is to use When to not catch the exception when a debugger is present:

Sub Main()
 
  Try
   
    RunApplication()
 
  Catch ex As Exception When Not System.Diagnostics.Debugger.IsAttached
    HandleGlobalException(ex)
 
  End Try End Sub

How do I determine if an assembly was built for debug or release?

If you want to determine if your assembly was built using debug or release, you would think you could use the FileVersionInfo.IsDebug or IsRelease; however, the compiler doesn't apparently set the proper bit as you would expect. Since that doesn't work, you could use the DebuggableAttribute on the assembly by using the following code.

Dim assm    
 
  As Reflection.Assembly = Reflection.Assembly.LoadFrom(Application.ExecutablePath)
 
  Dim found As   Boolean = assm.GetCustomAttributes(GetType(DebuggableAttribute),
     
      False).Length > 0          
          Me.Text = "Assembly is "
 & IIf(found, "debug", "release")

How do I load an image from a file using a file stream?

Protected Shared   Function GetImageFromFile(ByVal FileName As     String) As   Byte()
    
    Dim myFile As String = FileName
    
    Dim fs As  FileStream = New FileStream(myFile, FileMode.Open, FileAccess.Read)
    
    Dim br As BinaryReader = New BinaryReader(fs)
    
    Dim bytesize   As Long =   fs.Length
   ReDim GetImageFromFile(bytesize)
   GetImageFromFile = br.ReadBytes(bytesize)
   
   End Function

To use the above function:

Dim img As New Bitmap(New IO.MemoryStream(GetImageFromURL("c:\file.jpg")))
Me.BackgroundImage = img

How do I load an image from a URI address?

Function GetImageFromURL(ByVal url As String) As Byte()
Dim wr As HttpWebRequest =  DirectCast(WebRequest.Create(url),HttpWebRequest)
Dim wresponse As HttpWebResponse =DirectCast(wr.GetResponse, HttpWebResponse )
Dim responseStream As Stream = wresponse.GetResponseStream
Dim br As BinaryReader = New BinaryReader(responseStream)
Dim bytesize AsLong = wresponse.ContentLength
Return br.ReadBytes(bytesize)
End Function

To use the above function:

Dim img As   New Bitmap(New IO.MemoryStream(GetImageFromURL("http://s/n.JPG")))      
 Me.BackgroundImage = img

How do I generate a GUID (Globally Unique IDentifier)?

You can use the System.Guid class.

 Dim guid As String = System.Guid.NewGuid.ToString

> You can also control how the guid is formatted. For example, if you use ToString("N"), the dashes ("-") will be removed.

How to get client date and time

You can use java script function to show the date and time.

<script type="text/javascript">
    function displayTime()
    {
        var localTime = new Date();
        var year= localTime.getYear();
        var month= localTime.getMonth() +1;
        var date = localTime.getDate();
        var hours = localTime .getHours();
        var minutes = localTime .getMinutes();
        var seconds = localTime .getSeconds();    
        var div=document.getElementById("div1");
        div.innerText=year+"-"+month+"-"+date+" "+hours+":"+minutes+":"+seconds;
    } 
</script>

Then you can call it at web page.

<body onload="displayTime();">
    <form id="form2" runat="server">
    <div id="div1"></div>
    </form>
</body>

How to access a control by using JavaScript

Reference the ClientID property (or UniqueID) of the control in the JavaScript.

protected void Page_Load(object sender, EventArgs e)
{
    Button btn= new Button();
    btn.ID = "btn5";
    btn.Attributes.Add("runat", "server");
    btn.Attributes.Add("onclick", "pop('" + btn.ClientID + "')");
    btn.Text = "Test";
    this.form1.Controls.Add(btn);
}

function pop(InputBoxID)
{
    var InputControl = document.getElementById(InputBoxID);
    alert(InputControl.value);
}

Or you can use the following method:

btn.Attributes.Add("onclick", "pop(this)");
function pop(InputBox)
{
    alert(InputBox.value);
}

How to invoke a server-side function with JavaScript

Firstly, you can drag a server button and put the server function into the button Click even,

protected void Button1_Click(object sender, EventArgs e)
{
   FunctionName();
}

Secondly, you can call the server function at JavaScript by using the following code,

document.getElementById("Button1").click();

How to retrieve server side variables using JavaScript code

<asp:HiddenField ID="HiddenField1" runat="server" />

public partial class LoginDemo : System.Web.UI.Page
{   
    private string str="hello";
    protected void Page_Load(object sender, EventArgs e)
    {
        HiddenField1.Value=str;
    }
}

Then you can access the control HiddenField1 using javascipt:

<script type="text/JavaScript">
Var tt=document.getElementByID(“HiddenField1”);
alert(tt.value);
</script>

How to assign a value to a hidden field using JavaScript in ASP.NET

We can use JavaScript to set the value of a hidden control and get its value at the server after a post back.

<input id="Hidden1" type="hidden" /> <script type="text/JavaScript"> var str=”hello” document.getElementByID(“Hidden1”).value=str </script>

protected void Page_Load(object sender, EventArgs e) { string str=request["Hidden1"].ToString(); }

How to register the JavaScript function at Code-Behind

Use ResterStartupScript

this.Page.ClientScript.RegisterStartupScript(this.GetType(),"alert","<script>alert(‘hello’);</script>");

Use Literal control,

private void Button2_Click(object sender, System.EventArgs e) { string str; str="<script language='JavaScript'>"; str+="selectRange()"; str+="<script>"; Literal1.Text=str; }

How to display images with a delay of five second

With this script you can see clickable images rotating in real-time without requiring banner rotation software or page reloads/refreshes .You should see a new banner rotating every 5 seconds:

<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head id="Head1" runat="server"> <title>JavaScript</title> <script language="javascript" type="text/javascript"> var image=""; var banners=0; function loadbanners() { if (banners==1) { image="images/AJAX.gif"; } if (banners==2) { image="images/ASPDotNet.gif"; } if (banners==3) { image=" images/MSDN.gif"; } } function cycle() { if (++banners > 3) banners=1; loadbanners(); document.getElementById("banner1").src =image; window.setTimeout('cycle();',5000); } </script> </head> <body onload="cycle();"> <form id="form2" runat="server"> <div> <img alt="" id="banner1" src="images/start.png" /> </div> </form> </body> </html>

How to get browser screen settings and apply it to page controls

You can use the JavaScript, suppose the control type is <image>, see the code below:

<html> <body> <input onclick="resizeImage()"/> <img src="http://www.microsoft.com/library/toolbar/3.0/images/banners/ms_masthead_ltr.gif" id="Img1" /> <script language="JavaScript"> var winWidth = 0; var winHeight = 0; function resizeImage(){ var img=document.getElementById("testImage") if (window.innerWidth) winWidth = window.innerWidth; else if ((document.body) && (document.body.clientWidth)) winWidth = document.body.clientWidth; if (window.innerHeight) winHeight = window.innerHeight; else if ((document.body) && (document.body.clientHeight)) winHeight = document.body.clientHeight; if (document.documentElement && document.documentElement.clientHeight && document.documentElement.clientWidth) { winHeight = document.documentElement.clientHeight; winWidth = document.documentElement.clientWidth; } img.width= winHeight; img.width= winWidth; } </script> </body> </html>

How to clear the session when the user closes a window

Use the code,

<script type="text/javascript"> function window.onbeforeunload() { var xmlHttp; try { // Firefox, Opera 8.0+, Safari xmlHttp=new XMLHttpRequest(); } catch (e) { // Internet Explorer try { xmlHttp=new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { xmlHttp=new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) { alert("Your browser does not support AJAX!"); return false; } } if(event.clientX>document.body.clientWidth&&event.clientY<0||event.altKey) { xmlhttp.open("GET","exit.aspx",false); xmlhttp.send(); } } </script>

Ways to pass data between pages

How to use cookies

Create a page named page1.aspx, and then drag a button and a TextBox onto the page. Double click the button and then add the following code:

protected void Button1_Click(object sender, EventArgs e) { HttpCookie cookie = new HttpCookie("UserName"); cookie.Value = TextBox1.Text; cookie.Expires = DateTime.Now.AddDays(1); Response.Cookies.Add(cookie); Response.Redirect("Page2.aspx"); }

<div> <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" /> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> </div>

On page2.aspx, double click the form and put the following code in it:

protected void Page_Load(object sender, EventArgs e) { if (Request.Cookies["UserName"] != null) Response.Write(Request.Cookies["UserName"].Value); }

How to use QueryString

private void Button1_Click (object sender, System.EventArgs e) { string url; url="anotherwebform.aspx?name=" + TextBox1.Text + "&email=" + TextBox2.Text; Response.Redirect(url); }

Destination web form

private void Page_Load (object sender, System.EventArgs e) { Label1.Text=Request.QueryString["name"]; Label2.Text=Request.QueryString["email"]; }

How to use Session

private void Button1_Click(object sender, System.EventArgs e) { //Drag TextBox1 and TextBox2 onto a web form Session["name"]=TextBox1.Text; Session["email"]=TextBox2.Text; Server.Transfer("anotherwebform.aspx"); }

Destination web form

private void Page_Load(object sender, System.EventArgs e) { Label1.Text=Session["name"].ToString(); Label2.Text=Session["email"].ToString(); Session.Remove("name"); Session.Remove("email"); }

How to use Context

//Page1.aspx stores value in context before transferring Context.Items("UserName") = txtName.Text; Server.Transfer("Page2.aspx"); //Page2.aspx retrieves the value from Page1’s context string sName; sName = Context.Items("UserName").ToString; Response.Write("Your name is " + sName);

How to use PreviousPage
FirstForm.aspx
<asp:Button id="buttonPassValue" runat="server" Text="Button" PostBackUrl="~/SecondForm.aspx"> </asp:Button>

SecondForm.aspx.cs

TextBox1.Text = Request.Form["TextBox1"].ToString();

Or SecondForm.aspx.cs

TextBox textBoxTemp = (TextBox) PreviousPage.FindControl("TextBox1"); TextBox1.Text = textBoxTemp.Text;

As you’ve noticed, this is a simple and clean implementation of passing values between pages.

How to use Submit Form

page1.aspx,

<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <script language="javascript"> function CopyTextToHiddenField() { var textbox1Value = document.getElementById("<%=TextBox1.ClientID%>").value; document.forms[1].document.getElementById("Hidden1").value = textbox1Value; } </script> </head> <body> <form id="form1" runat="server"> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> </form> <form name="SubmittedForm" action="page2.aspx" method="post"> <input id="Submit1" type="submit" value="submit" onclick="CopyTextToHiddenField()" /> <input name="Hidden1" type="hidden" /> </form> </body> </html>

page2.aspx,

<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> protected void Page_Load(object sender, EventArgs e) { Response.Write(Request.Form["Hidden1"]); } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head id="Head1" runat="server"> </head> <body> <form id="form1" runat="server"> <div> </div> </form> </body> </html>

2.7        How to use Server.Transfer

page1.aspx,

<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> protected void Button_Click(object sender, EventArgs e) { Server.Transfer("page2.aspx", true); } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head id="Head1" runat="server"> </head> <body> <form id="form1" runat="server"> <div> <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button_Click" /> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> </div> </form> </body> </html>

page2.aspx,

<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> protected void Page_Load(object sender, EventArgs e) { Response.Write(Request.Form["TextBox1"]); } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head id="Head1" runat="server"> </head> <body> <form id="form1" runat="server"> <div> </div> </form> </body> </html>

How to upload a file

if (FileUpLoad1.HasFile) { FileUpLoad1.SaveAs(Server.MapPath("upload")+ "\\" + FileUpLoad1.FileName); }

Why upload fails when using an ASP.NET FileUpload control to upload large files

For security reasons, ASP.NET is limited in terms of an uploaded file size. The default maximum file size is 4 MB but this can be changed by modifying the MaxRequestLength attribute of Machine.config's <httpRuntime> element.

<httpRuntime executionTimeout="240" maxRequestLength="20480" />

How to upload an image files only

See the code,

Fileupload.aspx:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Fileupload.aspx.cs" Inherits="FileuploadDemo" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Upload Image Demo</title> </head> <body> <form id="form1" runat="server"> <div> <asp:Image ID="Image1" runat="server" /> <asp:FileUpload ID="FileUpload1" runat="server" /> <asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click" /> </div> </form> </body> </html>

Fileupload.aspx.cs:

using System; using System.Collections; using System.Configuration; using System.Data; using System.Linq; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Xml.Linq; public partial class FileuploadDemo : System.Web.UI.Page { protected void btnSubmit_Click(object sender, EventArgs e) { string fileFullname = this.FileUpload1.PostedFile.FileName; string dataName = DateTime.Now.ToString("yyyy-MM-dd hh-mm-ss"); string fileName = fileFullname.Substring(fileFullname.LastIndexOf("\\") + 1); string type = fileFullname.Substring(fileFullname.LastIndexOf(".") + 1); if (FileUpload1.PostedFile.ContentType.ToUpper().IndexOf("IMAGE") > -1) { System.Drawing.Image img = System.Drawing.Image.FromStream(FileUpload1.PostedFile.InputStream); int Width = img.Width; int Height = img.Height; if (Width > 1000 || Height > 1000 || FileUpload1.PostedFile.ContentLength > 1024 * 1024 * 200) { this.ClientScript.RegisterStartupScript(this.GetType(), "Startup", "<script language='javascript'>alert('The image size is too large!');</script>"); } else { if (type == "jpg" || type == "gif" || type == "bmp" || type == "JPG" || type == "GIF") { string ImagePath = "images/"; string sPath = Server.MapPath(ImagePath) + dataName + fileName; string imgPath = ImagePath + dataName + fileName; this.FileUpload1.PostedFile.SaveAs(sPath); this.ClientScript.RegisterStartupScript(this.GetType(), "Startup", "<script language='javascript'>alert('Success!');</script>"); this.Image1.ImageUrl = imgPath; this.btnSubmit.Enabled = false; this.btnSubmit.Text = "Success!"; this.btnSubmit.Enabled = true; } else { this.ClientScript.RegisterStartupScript(this.GetType(), "Startup", "<script language='javascript'>alert('File type is not right!');</script>"); } } } else { this.ClientScript.RegisterStartupScript(this.GetType(), "Startup", "<script language='javascript'>alert('The uploaded file is not a image file!');</script>"); } } }

How to get a File Upload control work with an UpdatePanel

The FileUpload control does not work with asynchronous post backs and therefore does not work from within an AJAX UpdatePanel.

The trick to make the FileUpload to work within an Ajax UpdatePanel is to setup a PostBackTrigger in the UpdatePanel control.

Demo code:

<asp:UpdatePanel ID="UpdatePanel1" runat="server"> <Triggers > <asp:PostBackTrigger ControlID ="Button1" /> </Triggers> <ContentTemplate > <asp:FileUpload ID ="fileupload1" runat ="server" /><br /> <asp:Button ID ="Button1" runat ="server" Text ="Upload" OnClick="Button1_Click" /><br /> <asp:Label ID ="Lable1" runat ="server" Text =""></asp:Label> <asp:LinkButton ID ="LinkButton1" runat="server" Text ="Click Here" OnClick="LinkButton1_Click"></asp:LinkButton> </ContentTemplate> </asp:UpdatePanel>

How to change the culture settings for a Calendar

In calendar.aspx.cs:

private void Page_Load(object sender, System.EventArgs e) { System.Globalization.CultureInfo culture = System.Globalization.CultureInfo.CreateSpecificCulture("ens"); System.Threading.Thread.CurrentThread.CurrentCulture = culture; System.Threading.Thread.CurrentThread.CurrentUICulture = culture; }

How to select multiple non-sequential dates at Code-Behind

Invoke the member function ‘Add’ of the control's SelectedDates collection. You can add dates in any sequence, because the collection will automatically arrange them in order for you.

protected void Calendar1_SelectionChanged(object sender, EventArgs e) { Calendar1.SelectedDates.Clear(); Calendar1.SelectedDates.Add(new DateTime(2008, 8, 1)); Calendar1.SelectedDates.Add(new DateTime(2008, 8, 7)); Calendar1.SelectedDates.Add(new DateTime(2008, 8, 15)); }

How to disable some dates in Calendar control

protected void Calendar1_DayRender(object sender, DayRenderEventArgs e) { string date="02/01/2008"; DateTime dt = DateTime.Parse(date); if (e.Day.Date == dt) e.Day.IsSelectable = false; }

How to extend Calendar control for Server-Side validation

How to set ToolTips and links in Calendar control’s DayRender event

protected void Calendar1_DayRender(object sender, DayRenderEventArgs e) { e.Cell.Controls.Clear(); HyperLink link = new HyperLink(); link.Text = e.Day.Date.Day; link.ToolTip = "anything you want here!"; link.NavigateUrl = url; e.Cell.Controls.Add(link); }

How to give some dates different appearances

We can do this with the following code:

protected void Calendar1_DayRender(object sender, DayRenderEventArgs e) { if (e.Day.Date.Month == 2 && e.Day.Date.Day == 25) { e.Cell.BackColor = System.Drawing.Color.Yellow; } if (e.Day.Date.DayOfWeek == DayOfWeek.Friday || e.Day.Date.DayOfWeek == DayOfWeek.Saturday) { e.Cell.Controls.Clear(); e.Cell.Text = "today isweekend"; } }

How to enable ASP.NET DropDownList with OptionGroup support

We can override the function of DropDownList, and add the additional property for it.

Here are some good articles about it.

How to disable an item in DropDownList

<asp:DropDownList ID="DropDownList1" runat ="server" Width="235px" AutoPostBack="False"> <asp:ListItem>1</asp:ListItem> <asp:ListItem>2</asp:ListItem> <asp:ListItem>3</asp:ListItem> <asp:ListItem>4</asp:ListItem> </asp:DropDownList>

protected void Page_Load(object sender, EventArgs e) { DropDownList1.Attributes.Add("onchange", "change();"); }

<script type ="text/javascript" > function change() { var dd=document.getElementById ('<%=DropDownList1.ClientID %>'); var value=dd.options[dd.selectedIndex].value; if(value!="2") //supose you want to disable the item numbered 2 { setTimeout("__doPostBack('DropDownList1','')", 0); } } </script>

     How to hold the selected value for a DropDownList

You should place your data binding code for the dropdownlist in the !page.Ispostback block.

the !postback block will ensure it will only be filled once during post backs.

if(!Page.IsPostBack) { //bind template drop down here }

How to add a new property to UserControl

You can setup new properties inside the class definition of the user control at its .ascx.cs file.Example:

ascx file,

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="WebUserControl.ascx.cs" Inherits="WebUserControl" %> <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label> <asp:Calendar ID="Calendar1" runat="server"></asp:Calendar> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

ascx.cs file,

public partial class WebUserControl : System.Web.UI.UserControl { String text2 = String.Empty; public String Text { get { return Label1 .Text ; } set { Label1 .Text = value; } } public String Text2 { get { return text2; } set { text2 = value; } } protected void Page_Load(object sender, EventArgs e) { TextBox1.Text = text2; } }

aspx file

<%@ Register src="WebUserControl.ascx" mce_src="WebUserControl.ascx" TagName="WebUserControl" TagPrefix="uc1" %> <uc1:WebUserControl id="WebUserControl1" runat="server" Text="Hello world" Text2="Hello world."> </uc1:WebUserControl>

How to access a dynamically created UserControl

You can use FindControl method to get a reference to the target child control of your user control and then use it just like any other controls.

Example:

UC.ascx,

<%@ Control Language="C#" ClassName="UC" %> <script runat="server"> </script> <asp:TextBox ID="txtName" runat="server"></asp:TextBox>

Page.aspx:

<%@ Page Language="C#" %> <%@ Register src="UC.ascx" tagname="UC" tagprefix="uc1" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> protected void btnLoad_Click(object sender, EventArgs e) { UC uc = new UC(); uc.LoadControl("~/uc/UC.ascx"); uc.ID = "MyUC"; form1.Controls.Add(uc); (form1.FindControl("MyUC").FindControl("txtName") as TextBox).Text = "ASP.NET"; } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>User Control Demo</title> </head> <body> <form id="form1" runat="server"> <div> <asp:Button ID="btnLoad" runat="server" Text="Loading user control ..." onclick="btnLoad_Click" /> </div> </form> </body> </html>

How to access a control inside a UserControl

Assume there is a user control called UC and there is only a TextBox control inside it. Now drag this user control into a web page, you can use the following code to visit the TextBox control.

((TextBox)UC1.FindControl("TextBox1")).Text = "demo";

How to create a dynamic control

We can create the dynamic control in the Page_Init() event or Page_Load() event,

protected void Page_Load(object sender, EventArgs e) { TextBox dynamicTextBox = new TextBox(); dynamicTextBox.ID = "DynamicTextBox"; dynamicTextBox.AutoPostBack = true; dynamicTextBox.Text = "InitData"; dynamicTextBox.TextChanged += new EventHandler(dynamicTextBox_TextChanged); this.Form.Controls.Add(dynamicTextBox); } void dynamicTextBox_TextChanged(object sender, EventArgs e) { Response.Write("hello"); }

How to access a user entered value in a dynamic created TextBox control

a.      Get the value from the form's POST data. Here is the code:

if(Request.Form["dynamicTextBox"] != null) selectedValue = Request.Form["dynamicTextBox"].ToString();

b.      Get the value by finding the control at the webpage.

TextBox txt=this.form1.FindControl("dynamicTextBox") as TextBox;

See the whole demo code,

<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <script runat="server"> public string Res = string.Empty; protected void Page_Load(object sender, EventArgs e) { TextBox dynamicTextBox = new TextBox(); dynamicTextBox.ID = "dynamicTextBox"; form1.Controls.Add(dynamicTextBox); } protected void btnForm_Click(object sender, EventArgs e) { lblMsg.Text += "<br /> Form way:"; if (Request.Form["dynamicTextBox"] != null) Res = Request.Form["dynamicTextBox"].ToString(); lblMsg.Text += Res; } protected void btnFindControl_Click(object sender, EventArgs e) { lblMsg.Text += "<br /> FindControl way: "; TextBox dynamicTextBox = this.form1.FindControl("dynamicTextBox") as TextBox; Res = dynamicTextBox.Text; lblMsg.Text += Res; } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Demo</title> </head> <body> <form id="form1" runat="server"> <div> <asp:Label ID="lblMsg" runat="server" Text=""></asp:Label> <asp:Button ID="btnForm" runat="server" Text="Form Way" OnClick="btnForm_Click" /> <asp:Button ID="btnFindControl" runat="server" Text="FindControl Way" OnClick="btnFindControl_Click" /> </div> </form> </body> </html>

Dynamic controls accessed by JavaScript

Reference the ClientID property (or UniqueID) of the control in the Javascript.

protected void Page_Load(object sender, EventArgs e) { Button btn= new Button(); btn.ID = "btn5"; btn.Attributes.Add("runat", "server"); btn.Attributes.Add("onclick", "pop('" + btn.ClientID + "')"); btn.Text = "Test"; this.form1.Controls.Add(btn); }

function pop(InputBoxID) { var InputControl = document.getElementById(InputBoxID); alert(InputControl.value); }

Or,

Use the following method.

btn.Attributes.Add("onclick", "pop(this)"); function pop(InputBox) { alert(InputBox.value); }

How to retain all added server controls dynamically after post back

You should recreate these dynamic control at Page_load or Page_init() function everytime.

protected void Page_Load(object sender, EventArgs e) { //recreate these dynamic control. }

Related posts:

Why dynamically created controls disappear after a post back

The dynamic button must be re-created on each post back, so remove the if(!Page.IsPostBack). It's probably better if you create the controls at the Page_Init event.

How to use with Code-Behind

Label1.Attributes.Add("style", "background-color:Red");

   How to use with JavaScript

document.getElementById("Label1").style.backgroundColor = "Red";

Add the following code inside of the “head” tag,

How to use with html

<link href="<%= CSS %>" rel="stylesheet" type="text/css" />

Note: CSS is valuable

Linked style sheet usually lives in <head> tag, but there is no need to worry if it is put inside <body> tag. As

As well, <head> tag must have a runat=”server” attribute.

How to set an image as Button’s background

<input name="Submit" type="button" value="" style="border-style: none; background-color: Transparent; background-image: url('bg.png'); width: 68px; height: 20px; vertical-align: middle;" />

How to color items in ListBox

Demo code:

<style type="text/css"> .optred{background-color:red;} .optblue{background-color:blue;} </style>

protected void Page_PreRender(object sender, EventArgs e) { bool flag=false; foreach (ListItem li in ListBox1.Items) { if (flag) { li.Attributes.Add("class", "optred"); flag = false; } else { li.Attributes.Add("class", "optblue"); flag = true; } } }

How to print a part of a web page with CSS

CSS CODE:

<style media="print"> .Noprint { display: none; } .Print { page-break-after: always; } </style>

HTML CODE:

<div class="Noprint"> I am not print; </div> <div class="Print"> I will print; </div>

How to print a part of a web page with JavaScript (1)

JavaScript CODE:

<script language="JavaScript" type="text/JavaScript"> function doPrint() { bdhtml=window.document.body.innerHTML; sprnstr=""; eprnstr=""; prnhtml=bdhtml.substr(bdhtml.indexOf(sprnstr)+17); prnhtml=prnhtml.substring(0,prnhtml.indexOf(eprnstr)); window.document.body.innerHTML=prnhtml; window.print(); } </script>

HTML CODE:

 This area will print!  <br /> I will not print? <input id="btnPrint" type="button" value="Print" onclick="doPrint()" />

How to print a part of a web page with JavaScript (2)

JavaScript CODE:

<script language="javascript" type="text/javascript"> function printdiv(divID) { var headstr = "<html><head><title></title></head><body>"; var footstr = "</body>"; var newstr = document.all.item(divID).innerHTML; var oldstr = document.body.innerHTML; document.body.innerHTML = headstr+newstr+footstr; window.print(); document.body.innerHTML = oldstr; return false; } </script>

HTML CODE: <input name="b_print" type="button" onclick="printdiv('divID');" value=" Print " /> <div id="divID"> <h1 style="color:green"> The Div content which you want to print</h1> </div>

What classes are needed to send e-mails in ASP.NET

Class MailMessage and SmtpMail are used to send emails from an ASP.NET application. MailMessage and SmtpMail are from System.Web.Mail namespace of .NET Framework 1.1 Class Library. Also, you can use System.Net.Mail instead of System.Web.Mail if you have .NET Framework version 2.0 installed.

How to send emails by using System.Net.Mail

CODE-BEHIND:

MailMessage message = new MailMessage(); message.From = new MailAddress("fromusername@DomainName"); message.To.Add(new MailAddress("tousername@DomainName")); message.CC.Add(new MailAddress("ccusername@DomainName")); message.Subject = "Subject"; message.Body = "Content"; SmtpClient client = new SmtpClient(); client.Send(message);

web.config:

<system.net> <mailSettings> <smtp from="username@DomainName"> <network host="SMTPServerName" port="25" userName="username" password="secret" defaultCredentials="true" /> </smtp> </mailSettings> </system.net>