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There is a master page with PlaceHolder on it. When a menu item is selected, it dynamically loads a user control ascx.

PlaceHolder1.Controls.Clear();
PlaceHolder1.Controls.Add("pages/MyControl.ascx");

But there's a button on MyControl, and there's a record in its source

 <asp:Button ID="reg" runat="server" OnClick="reg_Click" Text="Reg" Width="207px" />

Also, the callback is in codebehind for MyControl.

public partial class RegInit : System.Web.UI.UserControl
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void reg_Click(object sender, EventArgs e)
    {
        // never comes here
    }
}

But the reg_Click is never called.. what I see, is just the reload of the master page, when "Reg" button's clicked.

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  • Are you in WinForms and C++, or in ASP.NET WebForms and C#? Commented May 2, 2016 at 12:07

2 Answers 2

Reset to default
1

I have to publish my solution as well.

As to me, I think I found the better solution.

The idea of the user control is to be able to place many elementary controls on the panel and use them as one, and the second - the values in the elementary controls should be kept, whatever user enters, while he switches the set of user controls.

Now the solution. I just created all of my controls, but instead of using PlaceHolder, I explicitly put them on the same place of the Main Page, but with the property "Visible" set to False. Then, as the menu item is selected, I just set the property Visible of the appropriate control to True. Therefore, it works as should to..

To place a Control of the page use the tag Register: In my example there are 2 controls About and RegInit in MainPage.aspx:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="MainPage.aspx.cs" Inherits="MyApp.MainPage" %>
<%@ Register TagPrefix="uc" TagName="About" Src="~/controls/About.ascx" %>
<%@ Register TagPrefix="uc" TagName="RegInit" Src="~/controls/RegInit.ascx" %>

And below on their's place in code:

        <uc:About id="about" runat="server" Visible="true" />
        <uc:RegInit id="regInit" runat="server" Visible="false" />

And in MainPage.aspx.cs

protected void MainMenu_ItemClick(object sender, MenuEventArgs e)
{
    if (e.Item.Text == "ABOUT")
    {
        about.Visible = true;
        regInit.Visible = false;
    }
    if (e.Item.Text == "REGISTER")
    {
        regInit.Visible = true;
        about.Visible = false;
    }
}

It is much better, because all the user data which are entered is kept, and user could continue with them by switching the controls.

I will tick the Connor's solution, but I decided to get rid of the PlaceHolder...

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After the menu command has been selected, the user control must be loaded in the PlaceHolder on every postback. You can remember in a Session variable if the menu command has been selected.

// Property giving the show/hide status of the user control
private bool ShouldLoadMyControl
{
    get { return Session["LoadMyControl"] != null && (bool)Session["LoadMyControl"]; }
    set { Session["LoadMyControl"] = value; }
}

// Load the control on every postback (if option selected)
protected void Page_Load(object sender, EventArgs e)
{
    if (ShouldLoadMyControl)
    {
        LoadMyControl();
    }
}

// Utility function to load the user control
private void LoadMyControl()
{
    PlaceHolder1.Controls.Add(LoadControl("pages/MyControl.ascx"));
}

// Event handler for the command to show the control
protected void mnuLoadMyControl_Click(object sender, EventArgs e)
{
    if (!ShouldLoadMyControl)
    {
        ShouldLoadMyControl= true;
        LoadMyControl();
    }
}

// Event handler for a command to hide the control
protected void mnuHideMyControl_Click(object sender, EventArgs e)
{
    ShouldLoadMyControl= false;
    PlaceHolder1.Controls.Clear();
}
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1 Comment

I saw the same with ViewState. Well, I'll tick your post as the answer, because you answered exactly to the PlaceHolder case. But I decided to get rid of PlaceHolder, and use the Visible property of Control...

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