I am trying to add a double-click event in a listbox.
But I am getting the following error.
the aspx file
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ListBox__Test.aspx.cs" Inherits="DataBind__Various_Controls.ListBox__Test" %>
<!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></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ListBox ID="ListBox1" runat="server" Height="207px" Width="167px" AutoPostBack="True">
</asp:ListBox>
</div>
<div>
<asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
<br />
<asp:Button ID="btnForListBoxDoubleClick" runat="server" Text="Button" />
</div>
</form>
</body>
</html>
the cs file
namespace DataBind__Various_Controls
{
public partial class ListBox__Test : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
string postbackRef = ClientScript.GetPostBackEventReference(btnForListBoxDoubleClick, "dblClickfromHiddenButton"); //this.Page.GetPostBackClientEvent(btnForListBoxDoubleClick, "dblClickfromHiddenButton");
ListBox1.Attributes.Add("onclick", postbackRef);
}
}
private void btnForListBoxDoubleClick_ServerClick(object sender, System.EventArgs e)
{
string argument = Request.Params["__EVENTARGUMENT"].Trim();
if (argument == "dblClickfromHiddenButton")
{
this.Label1.Text = "Hello!";
}
}
}
}
the error page
Server Error in '/' Application.
Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.ArgumentException: Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[ArgumentException: Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.]
System.Web.UI.ClientScriptManager.ValidateEvent(String uniqueId, String argument) +8620921
System.Web.UI.Control.ValidateEvent(String uniqueID, String eventArgument) +72
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +35
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +175
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565
Version Information: Microsoft .NET Framework Version:2.0.50727.3053; ASP.NET Version:2.0.50727.3053
How can I solve the problem?