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IPostBackEventHandler Interface

Defines the method ASP.NET server controls must implement to handle post back events.

For a list of all members of this type, see IPostBackEventHandler Members.

[Visual Basic]
Public Interface IPostBackEventHandler
[C#]
public interface IPostBackEventHandler
[C++]
public __gc __interface IPostBackEventHandler
[JScript]
public interface IPostBackEventHandler

Classes that Implement IPostBackEventHandler

Class Description
Button Displays a push button control on the Web page.
Calendar Displays a single month calendar that allows the user to select dates and move to the next or previous month.
HtmlAnchor Allows programmatic access to the HTML <a> tag on the server.
HtmlButton Allows programmatic access to the HTML <button> tag on the server.
HtmlInputButton Allows programmatic access to the HTML <input type= button>, <input type= submit>, and <input type= reset> elements on the server.
HtmlInputImage Allows programmatic access to the HTML <input type= image> element on the server.
ImageButton A control that displays an image and responds to mouse clicks on the image.
LinkButton Displays a hyperlink style button control on a Web page.

Remarks

To create a server control that captures form submit information from the browser, you must implement this interface. For more information on how to use this interface, see Capturing Postback Events.

Example

[Visual Basic, C#, C++] The following example defines a custom button server control that causes post back, captures the post back event using the RaisePostBackEvent method, and raises a Click event on the server.

[Visual Basic] 
Imports System
Imports System.Web.UI
Imports System.Collections
Imports System.Collections.Specialized

Namespace CustomControls    
    
    <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> Public Class MyButton
        Inherits Control
        Implements IPostBackEventHandler
        
        ' Define the Click event.
        Public Event Click As EventHandler
        
        
        ' Invoke delegates registered with the Click event.
        Protected Overridable Sub OnClick(e As EventArgs)            
            RaiseEvent Click(Me, e)
        End Sub
        
        
        ' Define the method of IPostBackEventHandler that raises change events.
        Public Sub RaisePostBackEvent(eventArgument As String) _
        Implements IPostBackEventHandler.RaisePostBackEvent
        
            OnClick(New EventArgs())
        End Sub       
        
        
        Protected Overrides Sub Render(output As HtmlTextWriter)
            output.Write("<INPUT TYPE = submit name = " & Me.UniqueID & _
                " Value = 'Click Me' />")
        End Sub
        
    End Class
End Namespace


[C#] 
using System;
using System.Web.UI;
using System.Collections;
using System.Collections.Specialized;

namespace CustomControls {

   [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")]   
   public class MyButton: Control, IPostBackEventHandler {
      
      // Defines the Click event.
      public event EventHandler Click;
      
      //Invoke delegates registered with the Click event.
      protected virtual void OnClick(EventArgs e) {
         
         if (Click != null) {
            Click(this, e);
         }   
      }
      
      
      // Define the method of IPostBackEventHandler that raises change events.
      public void RaisePostBackEvent(string eventArgument){
         
         OnClick(new EventArgs());
      }
      
      
      protected override void Render(HtmlTextWriter output) {
         output.Write("<INPUT TYPE = submit name = " + this.UniqueID + 
            " Value = 'Click Me' />");   
      }
   }    
}
   

[C++] 
#using <mscorlib.dll>
#using <System.Web.dll>
#using <System.dll>
using namespace System;
using namespace System::Web::UI;
using namespace System::Collections;
using namespace System::Collections::Specialized;

[System::Security::Permissions::PermissionSet(System::Security::Permissions::SecurityAction::Demand, Name=S"FullTrust")]   
public __gc class MyButton: public Control, public IPostBackEventHandler {

   // Defines the Click event.
public:
   __event EventHandler* Click;

   //Invoke delegates registered with the Click event.
protected:
   virtual void OnClick(EventArgs* e) {

      if (Click != 0) {
         Click(this, e);
      }   
   }


   // Define the method of IPostBackEventHandler that raises change events.
public:
   void RaisePostBackEvent(String* eventArgument){

      OnClick(new EventArgs());
   }


protected:
   void Render(HtmlTextWriter* output) {
      output->Write(S"<INPUT TYPE = submit name = {0} Value = 'Click Me' />", this->UniqueID);   
   }
};    

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Web.UI

Platforms: Windows 2000, Windows XP Professional, Windows Server 2003 family

Assembly: System.Web (in System.Web.dll)

See Also

IPostBackEventHandler Members | System.Web.UI Namespace | Capturing Postback Events

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