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Editorial Team
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Asked: 2026-05-25T00:57:33+00:00

I have a form with an update panel, inside of the update panel is

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I have a form with an update panel, inside of the update panel is a div runat=”server”. I am dynamically adding user controls to this div. Inside of the user control is a link button. I would like to raise a Click event on this link button. I know that I must add the trigger dynamically as well. I am attempting to do this on the user control’s ‘Page_Load’ event using reflexion.

//Inside User Control
protected void Page_Load(object sender, EventArgs e)
{
this.Page.GetType().InvokeMember("AddTrigger", System.Reflection.BindingFlags.InvokeMethod, null, this.Page, new object[] { this.lbDetails.UniqueID, "Click"});
}

//On the page
public void AddTrigger(string controlId, string eventName)
{
    AsyncPostBackTrigger trigger = new AsyncPostBackTrigger();
    trigger.ControlID = controlId;
    trigger.EventName = eventName;
    this.upContent.Triggers.Add(trigger);
}

This appears to be happening correctly, I can see the update panel triggers collection having the new trigger. Although, the trigger control name attribute does have the user control name as a prefix.. I am passing the uniqueId as the control name attribute for the async trigger (e.g. ctl11$lbDetails)… The Event is just ‘Click’. This does not appear to be working. When I click the linkButton the event handler method is not firing..

Thanks in Advance guys??

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1 Answer

  1. Editorial Team

    Ok, I found a work around which does not involve using triggers or the scriptManager registry.

    This is the page

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

<%@ Register TagPrefix="uc" TagName="A" Src="~/UserControls/ucA.ascx" %>
<html>
<head>
    <title>Example</title>
</head>
<body>
    <form id="Form1" action="Default.aspx" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <asp:UpdatePanel ID="upMain" runat="server" ChildrenAsTriggers="false" UpdateMode="Conditional">
        <ContentTemplate>
            <div id="divContent" runat="server">
            </div>
        </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />
        </Triggers>
    </asp:UpdatePanel>
    <asp:Button ID="Button1" runat="server" Text="Button" OnClick="BtnClick" />
    <asp:PlaceHolder ID="phMain" runat="server">
    </asp:PlaceHolder>
    </form>
</body>
</html>

    This is the page code behind

    using System;
using System.Collections.Generic;
using System.Web.UI;
using System.Web.UI.WebControls;
using TestProject.UserControls;

namespace TestProject
{
    public partial class _Default : Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                divContent.InnerHtml =
                    "<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. Sed cursus ante" + 
                    " dapibus diam. Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. Fusce" +
                    " nec tellus sed augue semper porta. Mauris massa. Vestibulum lacinia arcu eget nulla. Class aptent taciti sociosqu" +
                    " ad litora torquent per conubia nostra, per inceptos himenaeos. Curabitur sodales ligula in libero. Sed dignissim" +
                    " lacinia nunc. </p>" +
                    "<p>Curabitur tortor. Pellentesque nibh. Aenean quam. In scelerisque sem at dolor. Maecenas mattis. Sed convallis" +
                    " tristique sem. Proin ut ligula vel nunc egestas porttitor. Morbi lectus risus, iaculis vel, suscipit quis, luctus" +
                    " non, massa. Fusce ac turpis quis ligula lacinia aliquet. Mauris ipsum. Nulla metus metus, ullamcorper vel, tincidunt" +
                    " sed, euismod in, nibh. Quisque volutpat condimentum velit. Class aptent taciti sociosqu ad litora torquent per conubia" +
                    " nostra, per inceptos himenaeos. </p>" +
                    "<p>Nam nec ante. Sed lacinia, urna non tincidunt mattis, tortor neque adipiscing diam, a cursus ipsum ante quis turpis." +
                    " Nulla facilisi. Ut fringilla. Suspendisse potenti. Nunc feugiat mi a tellus consequat imperdiet. Vestibulum sapien. Proin" +
                    " quam. Etiam ultrices. Suspendisse in justo eu magna luctus suscipit. Sed lectus. Integer euismod lacus luctus magna. Quisque" +
                    " cursus, metus vitae pharetra auctor, sem massa mattis sem, at interdum magna augue eget diam. Vestibulum ante ipsum primis in" +
                    " faucibus orci luctus et ultrices posuere cubilia Curae; Morbi lacinia molestie dui. </p>" +
                    "<p>Praesent blandit dolor. Sed non quam. In vel mi sit amet augue congue elementum. Morbi in ipsum sit amet pede facilisis" +
                    " laoreet. Donec lacus nunc, viverra nec, blandit vel, egestas et, augue. Vestibulum tincidunt malesuada tellus. Ut ultrices" +
                    " ultrices enim. Curabitur sit amet mauris. Morbi in dui quis est pulvinar ullamcorper. Nulla facilisi. Integer lacinia sollicitudin" +
                    " massa. Cras metus. </p>" +
                    "<p>Sed aliquet risus a tortor. Integer id quam. Morbi mi. Quisque nisl felis, venenatis tristique, dignissim in, ultrices sit amet," +
                    " augue. Proin sodales libero eget ante. Nulla quam. Aenean laoreet. Vestibulum nisi lectus, commodo ac, facilisis ac, ultricies eu," +
                    " pede. Ut orci risus, accumsan porttitor, cursus quis, aliquet eget, justo. Sed pretium blandit orci. Ut eu diam at pede suscipit" +
                    " sodales. Aenean lectus elit, fermentum non, convallis id, sagittis at, neque. Nullam mauris orci, aliquet et, iaculis et, viverra" +
                    " vitae, ligula. </p>";

                //Clear session on first load
                Session["controls"] = null;
            }

            if (Session["controls"] != null)
            {
                RenderControls(Session["controls"] as List<Control>);
                var postbackInit = GetPostBackControl(this);
                LbClick(postbackInit, null);
            }
        }

        //Get Control that caused postback
        public static Control GetPostBackControl(Page page)
        {
            Control control = null;

            string ctrlname = page.Request.Params.Get("__EVENTTARGET");
            if (!string.IsNullOrEmpty(ctrlname))
            {
                control = page.FindControl(ctrlname);
            }
            else
            {
                foreach (string ctl in page.Request.Form)
                {
                    Control c = page.FindControl(ctl);
                    if (c is Button)
                    {
                        control = c;
                        break;
                    }
                }
            }
            return control;
        }

        public void Partial_Postback(ucA sender)
        {
            var counter = 5;
            var controls = new List<Control>();
            sender.Key = counter;
            sender.ID = counter.ToString();

            controls.Add(sender);
            Session["controls"] = controls;
            RenderControls(controls);
            sender.LbDetails.ID = counter.ToString();
        }

        private void RenderControls(List<Control> controls)
        {
            foreach (var control in controls)
            {
                var controlReference = Page.FindControl(control.ID);
                if (controlReference == null)
                {
                    divContent.Controls.Add(control);
                }
            }
            upMain.Update();
        }

        private void LbClick(object sender, EventArgs e)
        {
            divContent.InnerHtml = string.Empty;
            divContent.InnerText = string.Format("trigger works and ID = {0}", (sender as LinkButton).ID);
            upMain.Update();
        }

        public void BtnClick(object sender, EventArgs e)
        {
            var controlA = new ucA();
            controlA = (ucA)LoadControl("~/UserControls/ucA.ascx");
            divContent.Controls.Add(controlA);
        }
    }
}

    This is the user control

    <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="ucA.ascx.cs" Inherits="TestProject.UserControls.ucA" %>

<asp:LinkButton ID="LinkButton1" runat="server" ToolTip="This is the tool tip">Click Me to Remove Text</asp:LinkButton>

    This is the user control code behind

    using System;
using System.Reflection;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace TestProject.UserControls
{
    public partial class ucA : UserControl
    {
        public int Key;

        public LinkButton LbDetails
        {
            get { return this.LinkButton1; }
            set { LinkButton1 = value; }
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            Page.GetType().InvokeMember("Partial_Postback", BindingFlags.InvokeMethod, null, Page, new object[] { this });
        }
    }
}
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