icallbackeventHandler in asp.net 3.5

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hi i am trying to learn ICallbackEventHandler.
so for this i took label and button server control in aspx page.
like as follows

<head  runat="server">
    <title></title>
    <script type="text/javascript">
        function scriptevent(result, context) {

            if (document.getElementById("lbl") != null) {
                document.getElementById("lbl").value = result;
            }
        
        }
    
    </script>
</head>
<body>
    <form id="form1"  runat="server">
    <div>
   
    <label id="lbl"  runat="server"></label>
    <asp:Button ID="bttn" Text="print" runat="server"  />
    </div> 
    </form>
</body>

and my code behind page is

public partial class testPag1e : System.Web.UI.Page, ICallbackEventHandler
    {
        protected string text=string.Empty;
        protected void Page_Load(object sender, EventArgs e)
        {
            string refscript = this.Page.ClientScript.GetCallbackEventReference(this, "", "scriptevent", null, true);
            bttn.Attributes["OnClick"] = refscript;

        }

        #region ICallbackEventHandler Members

        public string GetCallbackResult()
        {
            text = "sunny";
            return text;
        }

        public void RaiseCallbackEvent(string eventArgument)
        {
           // text = eventArgument;
        }

        #endregion
    }

when i click on button it doesnt set text property of label control to "sunny"
can anyone help me out

Posted 13-Apr-11 1:15am

spydeehunk

Updated 13-Apr-11 1:18am

Toniyo Jackson

v3

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Comments

Toniyo Jackson 13-Apr-11 7:18am

Added pre tag

Slacker007 13-Apr-11 7:30am

If you are going to go through the trouble of adding a <pre> tag then why don't you edit the grammar and spelling while you are at it. Just a thought.

Toniyo Jackson 13-Apr-11 7:34am

Yes. I will do it from next time. :)

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sandeep Mewara · Answer 1 · 2011-04-13T03:04:00

Did you try to debug and see how the execution went?
You have not handled the operations required during the callback out here.

This is not the way to do it:

string refscript = this.Page.ClientScript.GetCallbackEventReference(this, "", "scriptevent", null, true);
            bttn.Attributes["OnClick"] = refscript;

In correct. You need to register the callbackevent refernece with page.

Have a look at this MSDN example: Client-Callback Implementation (C#) Example[^]
MSDN: Another detailed explanation[^]

Further, have a look at this article with sample. It would help you to dig deeper and learn: ClientCallback custom control for web applications[^]

icallbackeventHandler in asp.net 3.5

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icallbackeventHandler in asp.net 3.5

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