ClientScriptManager.GetPostBackEventReference Method (Control, String) (System.Web.UI)

GetPostBackEventReference Method (C...

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Microsoft Visual Studio 2005/.NET Framework 2.0

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.NET Framework Class Library

ClientScriptManager.GetPostBackEventReference Method (Control, String)

Note: This method is new in the .NET Framework version 2.0.

Returns a string that can be used in a client event to cause postback to the server. The reference string is defined by the specified control that handles the postback and a string argument of additional event information.

Namespace: System.Web.UI
Assembly: System.Web (in system.web.dll)

Syntax

Visual Basic (Declaration)

Public Function GetPostBackEventReference ( _
    control As Control, _
    argument As String _
) As String

Visual Basic (Usage)

Dim instance As ClientScriptManager
Dim control As Control
Dim argument As String
Dim returnValue As String

returnValue = instance.GetPostBackEventReference(control, argument)

public string GetPostBackEventReference (
    Control control,
    string argument
)

C++

public:
String^ GetPostBackEventReference (
    Control^ control, 
    String^ argument
)

public String GetPostBackEventReference (
    Control control, 
    String argument
)

JScript

public function GetPostBackEventReference (
    control : Control, 
    argument : String
) : String

Parameters

control: The server Control that processes the postback on the server.

argument: A string of optional arguments to pass to the control that processes the postback.

Return Value

A string that, when treated as script on the client, initiates the postback.

Exceptions

Exception type	Condition
ArgumentNullException	The specified Control is a null reference (Nothing in Visual Basic).

Remarks

To implement the IPostBackEventHandler interface for a Page, use the @ Implements directive.

The GetPostBackEventReference method can be used with the Button control when the UseSubmitBehavior property is false. In this scenario, the GetPostBackEventReference method returns the client postback event for the Button control.

Example

The following code example demonstrates the use of the GetPostBackEventReference method. The custom control, MyControl, implements the IPostBackEventHandler interface. When the button on the page is clicked, the RaisePostBackEvent method of the custom control is invoked.

Visual Basic

<%@ Page Language="VB" %>

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

<script runat="server">
  
  Public Class MyControl
    Inherits Label
    Implements IPostBackEventHandler
     
    Public Sub New()
      
      MyBase.Text = "No postback raised."
    
    End Sub
    
    Public Sub RaisePostBackEvent(ByVal eventArgument As String) Implements System.Web.UI.IPostBackEventHandler.RaisePostBackEvent
      
      MyBase.Text = "Postback handled by " & Me.ID.ToString() & ". <br/>" & _
                "Postback caused by " + eventArgument.ToString() & "."

    End Sub
    
  End Class
   

  Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

    ' Get a ClientScriptManager reference from the Page class.
    Dim cs As ClientScriptManager = Page.ClientScript

    ' Create an instance of the custom label control and 
    ' add it to the page.
    Dim mycontrol As New MyControl()
    MyControl.ID = "mycontrol1"
    PlaceHolder1.Controls.Add(MyControl)
    PlaceHolder1.Controls.Add(New LiteralControl("<br/>"))
    
    ' Create a button element with its onClick attribute defined
    ' to create a postback event reference to the custom label control.
    Dim b As New HtmlInputButton()
    b.ID = "mybutton1"
    b.Value = "Click"
    b.Attributes.Add("onclick", cs.GetPostBackEventReference(MyControl, b.ID.ToString()))
    PlaceHolder1.Controls.Add(b)
    PlaceHolder1.Controls.Add(New LiteralControl("<br/>"))
    
    ' Create a link element with its href attribute defined
    ' to create a postback event reference to the custom label control.
    Dim a As New HtmlAnchor()
    a.ID = "myanchor1"
    a.InnerText = "link"
    a.HRef = cs.GetPostBackClientHyperlink(MyControl, a.ID.ToString())
    PlaceHolder1.Controls.Add(a)
    
  End Sub
</script>

<html  >
<head id="Head1" runat="server">
    <title>ClientScriptManager Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <asp:PlaceHolder id="PlaceHolder1" 
                       runat="server">
      </asp:PlaceHolder>
    </div>
    </form>
</body>
</html>

<%@ 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 class MyControl : Label, IPostBackEventHandler
  {

    // Use the constructor to defined default label text.
    public MyControl()
    {
      base.Text = "No postback raised.";
    }
    
    // Implement the RaisePostBackEvent method from the
    // IPostBackEventHandler interface. 
    public void RaisePostBackEvent(string eventArgument)
    {
      base.Text = "Postback handled by " + this.ID.ToString() + ". <br/>" +
                  "Postback caused by " + eventArgument.ToString() + ".";
      
    }
  }

  protected void Page_Load(object sender, EventArgs e)
  {
    // Get a ClientScriptManager reference from the Page class.
    ClientScriptManager cs = Page.ClientScript;

    // Create an instance of the custom label control and 
    // add it to the page.
    MyControl mycontrol = new MyControl();
    mycontrol.ID = "mycontrol1";
    PlaceHolder1.Controls.Add(mycontrol);
    PlaceHolder1.Controls.Add(new LiteralControl("<br/>"));
    
    // Create a button element with its onClick attribute defined
    // to create a postback event reference to the custom label control.
    HtmlInputButton b = new HtmlInputButton();
    b.ID = "mybutton1";
    b.Value = "Click";
    b.Attributes.Add("onclick", cs.GetPostBackEventReference(mycontrol, b.ID.ToString()));
    PlaceHolder1.Controls.Add(b);
    PlaceHolder1.Controls.Add(new LiteralControl("<br/>"));
    
    // Create a link element with its href attribute defined
    // to create a postback event reference to the custom label control.
    HtmlAnchor a = new HtmlAnchor();
    a.ID = "myanchor1";
    a.InnerText = "link";
    a.HRef = cs.GetPostBackClientHyperlink(mycontrol, a.ID.ToString());
    PlaceHolder1.Controls.Add(a);
  }
</script>

<html  >
<head runat="server">
    <title>ClientScriptManager Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <asp:PlaceHolder id="PlaceHolder1" 
                       runat="server">
      </asp:PlaceHolder>
    </div>
    </form>
</body>
</html>

The following code example has the same functionality as the preceding one, except that instead of a custom control, the Page class implements the IPostBackEventHandler interface.

Visual Basic

<%@ Page Language="VB" %>
<%@ Implements Interface="System.Web.UI.IPostBackEventHandler" %>

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

<script runat="server">
 
  Public Sub RaisePostBackEvent(ByVal eventArgument As String) _
    Implements IPostBackEventHandler.RaisePostBackEvent
    
    Label1.Text = "Postback handled by " & Me.ID.ToString() & ". <br/>" & _
           "Postback caused by " + eventArgument.ToString() & "."
  
  End Sub
  

  Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

    ' Get a ClientScriptManager reference from the Page class.
    Dim cs As ClientScriptManager = Page.ClientScript
    
    ' Create a button element with its onClick attribute defined
    ' to create a postback event reference to the custom label control.
    Dim b As New HtmlInputButton()
    b.ID = "mybutton1"
    b.Value = "Click"
    b.Attributes.Add("onclick", cs.GetPostBackEventReference(Me, b.ID.ToString()))
    PlaceHolder1.Controls.Add(b)
    PlaceHolder1.Controls.Add(New LiteralControl("<br/>"))
    
    ' Create a link element with its href attribute defined
    ' to create a postback event reference to the custom label control.
    Dim a As New HtmlAnchor()
    a.ID = "myanchor1"
    a.InnerText = "link"
    a.HRef = cs.GetPostBackClientHyperlink(Me, a.ID.ToString())
    PlaceHolder1.Controls.Add(a)
    
  End Sub
</script>

<html  >
<head runat="server">
    <title>ClientScriptManager Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <asp:Label id="Label1"
                 runat="server" />
      <br />
      <asp:PlaceHolder id="PlaceHolder1" 
                       runat="server">
      </asp:PlaceHolder>
    </div>
    </form>
</body>
</html>

<%@ Page Language="C#"  %>
<%@ Implements Interface="System.Web.UI.IPostBackEventHandler" %>

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

<script runat="server">
  
  public void RaisePostBackEvent(string eventArgument)
  {
    Label1.Text = "Postback handled by " + this.ID.ToString() + ". <br/>" +
                  "Postback caused by " + eventArgument.ToString() + "."; ;
  }
  
  protected void Page_Load(object sender, EventArgs e)
  {
    // Get a ClientScriptManager reference from the Page class.
    ClientScriptManager cs = Page.ClientScript;
    
    // Create a button element with its onClick attribute defined
    // to create a postback event reference to the custom label control.
    HtmlInputButton b = new HtmlInputButton();
    b.ID = "mybutton1";
    b.Value = "Click";
    b.Attributes.Add("onclick", cs.GetPostBackEventReference(this, b.ID.ToString()));
    PlaceHolder1.Controls.Add(b);
    PlaceHolder1.Controls.Add(new LiteralControl("<br/>"));
    
    // Create a link element with its href attribute defined
    // to create a postback event reference to the custom label control.
    HtmlAnchor a = new HtmlAnchor();
    a.ID = "myanchor1";
    a.InnerText = "link";
    a.HRef = cs.GetPostBackClientHyperlink(this, a.ID.ToString());
    PlaceHolder1.Controls.Add(a);
  }
</script>

<html  >
<head runat="server">
    <title>ClientScriptManager Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <asp:Label id="Label1"
                 runat="server" />
      <br />
      <asp:PlaceHolder id="PlaceHolder1" 
                       runat="server">
      </asp:PlaceHolder>
    </div>
    </form>
</body>
</html>

Platforms

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

Version Information

.NET Framework

Supported in: 2.0

Reference

ClientScriptManager Class
ClientScriptManager Members
System.Web.UI Namespace
PostBackOptions
IPostBackEventHandler

Other Resources

Implementing Client Callbacks Without Postbacks in ASP.NET Web Pages