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ASP.NET AJAX: Firing an UpdatePanel after the page load is complete

I'm sure this is easy but I can't figure it out:

I have an ASP.NET page with some UpdatePanels on it. I want the page to completely load with some 'Please wait' text in the UpdatePanels. Then once the page is completely loaded I want to call a code-behind function to update the UpdatePanel.

Any ideas as to what combination of Javascript and code-behind I need to implement this idea?

SAL

PS: I've tried putting my function call in the Page_Load but then code is run before the page is delivered and, as the function I want to run takes some time, the page simply takes too long to load up.

like image 200
SAL Avatar asked Aug 28 '08 09:08

SAL


3 Answers

I fiddled around with the ScriptManager suggestions - which I reckon I would have eventually got working but it seems to me that the Timer idea is easier to implement and not really(!) that much of a hack?!

Here's how I got my panel updated after the initial page render was complete...

default.aspx

    <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="AJAXPostLoadCall._Default" %>

<!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>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <h2>And now for a magic trick...</h2>
    <asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="True">
        </asp:ScriptManager>
        <div>
            <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                <ContentTemplate>
                    <asp:Timer ID="Timer1" runat="server" Interval="2000" ontick="Timer1_Tick" />
                    <asp:Label ID="Label1" runat="server">Something magic is about to happen...</asp:Label>
                </ContentTemplate>
            </asp:UpdatePanel>

        </div>
    </form>
</body>
</html>

and the code behind default.aspx.cs reads

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

namespace AJAXPostLoadCall
{
    public partial class _Default : System.Web.UI.Page
    {

        protected void Page_Load(object sender, EventArgs e)
        {
        }

        public void DoMagic()
        {
            Label1.Text = "Abracadabra";
        }

        protected void Timer1_Tick(object sender, EventArgs e)
        {
            // Do the magic, then disable the timer
            DoMagic();
            Timer1.Enabled = false;
        }

    }
}

So, the page loads up and the Timer (contained within the UpdatePanel) fires 2 secs after the page has loaded up (I think - I'm not sure when the Timer actually starts?). The label text is rewritten and then the Timer is disabled to stop any more updates.

Simple enough - but can you purists out there tell me if this is a Horrible Hack?

like image 114
SAL Avatar answered Sep 20 '22 14:09

SAL


Have a look at ScriptManager.RegisterStartupScript

The idea is that you register a script to run on start up (I believe once the page has loaded). Your script should call a function that causes a post back through your UpdatePanel

like image 21
Tom Carter Avatar answered Sep 16 '22 14:09

Tom Carter


Use a timer control that will be fired after a certain number of milliseconds (for page to load). In the timer tick event refresh the update panel.

like image 24
moza Avatar answered Sep 20 '22 14:09

moza