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<%@ Page Language="C#" %>
<%@ Implements Interface="System.Web.UI.ICallbackEventHandler" %>
<!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" >
<script runat="server" >
string _eventName = "Fail";
string _cbMessage = "";
// Define method that processes the callbacks on server.
public void RaiseCallbackEvent(String eventArgument)
{
try {
this.ClientScript.ValidateEvent (_eventName, this.ToString ());
_cbMessage = "Correct event raised callback.";
}
catch (Exception ex) {
_cbMessage = "Incorrect event raised callback.";
}
}
// Define method that returns callback result.
public string GetCallbackResult()
{
return _cbMessage;
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
ClientScriptManager cs = Page.ClientScript;
String cbReference = cs.GetCallbackEventReference ("'" +
Page.UniqueID + "'", "arg", "ReceiveServerData", "",
"ProcessCallBackError", false);
String callbackScript = "function CallTheServer(arg, context) {" +
cbReference + "; }";
cs.RegisterClientScriptBlock (this.GetType (), "CallTheServer",
callbackScript, true);
}
}
protected override void Render(HtmlTextWriter writer)
{
this.ClientScript.RegisterForEventValidation("Test", this.ToString());
base.Render(writer);
}
</script>
<script type="text/javascript">
var value1 = new Date();
function ReceiveServerData(arg, context)
{
Message.innerText = arg;
Label1.innerText = "Callback completed at " + value1;
value1 = new Date();
}
function ProcessCallBackError(arg, context)
{
Message.innerText = 'An error has occurred.';
}
</script>
<html >
<head id="Head1" runat="server">
<title>CallBack Event Validation Example</title>
</head>
<body>
<form id="Form1" runat="server">
<div>
Callback result: <span id="Message"></span>
<br /> <br />
<input type="button"
id="button1"
runat="server"
value="ClientCallBack"
onclick="CallTheServer(value1, null )"/>
<br /> <br />
<asp:Label id="Label1" runat="server"/>
</div>
</form>
</body>
</html>
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