Client Side Web Development

Re: Callback in 2.0 renders an "Object Expected" Error

NC01 — Sun, 26 Mar 2006 11:00:48 GMT

Glad you got it. Can't believe that MS would have a broken sample, but I've seen it before.

NC...

Re: Callback in 2.0 renders an "Object Expected" Error

wotmman — Sat, 25 Mar 2006 15:07:28 GMT

Never mind all. My fault. After hours of research and digging through the vb code, i realized I was missing a "t" in my input onclick= call to the function calling getime instead of gettime.

Sorry.

Re: Callback in 2.0 renders an "Object Expected" Error

wotmman — Sat, 25 Mar 2006 13:08:00 GMT

Thanks for the links. I've read through them and tried a few things but still could not get it to work. (interesting to see the micorsoft link shows a sample of a sub statement that has a Return line in it. This error for me and says you cannont Return a value from this type of routine)

As for the line of error on View Source, it appears this is the line being referrenced:

function UseCallback(arg, context){WebForm_DoCallback('__Page',arg,GetServerTime,context,null,false); }// -->

The object Expected error must refer to one of these compoonents, I'm just not sure which one.

Re: Callback in 2.0 renders an "Object Expected" Error

NC01 — Sat, 25 Mar 2006 12:19:36 GMT

Do a View Source in your browser and see what that line points to. Also, here are a couple of links that might help you out.

http://msdn2.microsoft.com/en-us/library/ms178208.aspx
http://west-wind.com/weblog/posts/2694.aspx

NC...

Callback in 2.0 renders an "Object Expected" Error

wotmman — Sat, 25 Mar 2006 02:06:18 GMT

I've been trying to just create a simple function to utlize the new Callback feature of 2.0. I've copied the code right out of the book. I did find a few simple typos in the book (such as Sub with end fuction instead of end sub), otherwise, I've followed all the steps and still get an error code when I try to run the javascript with ICallbackeventhandler. I'm attaching my aspx file and vb file for anyone who might be able to find why I cannot get this to run. Thanks in advance for your help:

aspx:

<%@ Page Language="VB" AutoEventWireup="true" CodeFile="time.aspx.vb" Inherits="companytour_Default2" EnableEventValidation="true"%>

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

<title>Untitled Page</title>

function gettime(){

UseCallback();

}

function GetServerTime(txtTextbox1, context){

document.forms[0].Textbox1.value = Textbox1;

}

</script>

</head>

<body>

<div>

<asp:textbox ID="Textbox1" runat="server"></asp:textbox>

<p />

</div></form>

</body>

</html>

# NOW THE VB CODE #

Partial Class companytour_Default2

Inherits System.Web.UI.Page

Implements System.Web.UI.ICallbackEventHandler

Dim _callbackResult As String = Nothing

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

Dim cbReference As String = Page.ClientScript.GetCallbackEventReference(Me, "arg", "GetServerTime", "context")

Dim cbScript As String = "function UseCallback(arg, context)" & "{" & cbReference & "; }"

Page.ClientScript.RegisterClientScriptBlock(Me.GetType(), "UseCallback", cbScript, True)

End Sub

Public Sub RaiseCallbackEvent(ByVal eventArgument As String) Implements System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent

_callbackResult = Date.Now.ToString

End Sub

Public Function GetCallbackResult() As String Implements System.Web.UI.ICallbackEventHandler.GetCallbackResult

Return _callbackResult

End Function

End Class

This is the basic sample in the book Professional ASP.NET 2.0 by Wrox Publishing. It seems conceptually very simple. When I run the page, it displays fine. However, when I click the textbox, nothing happens and an Errror displays on the bottom of the page. When I click on the error details I get the following:

Line: 57

Char: 1

Error: Object Expected

Code: 0