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ViewState Issue for User Control

Posted on 2009-07-10
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Medium Priority
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Last Modified: 2013-12-17
Hi.  I currently have a user control that is sitting on the UI/Presentation Layer like so:

1. Default.aspx has the User Control in the design area.
2. The User Control is setting an event for a delegate.
3. The page reloads when the "Update" button is pressed within the User Control.
4. (After pressing Update from the User Control), On the Page_Load in Default.aspx.cs, if I look at the event value for the user control (CtnlEditTask.CurrentTaskClick), it shows up null.  That event should be set up (see step 2).

How can I get the page_load to properly remember what the event's prior setting is?
Default.aspx.cs:
    protected void Page_Load(object sender, EventArgs e)
    {
        CtnlEditTask.EnableViewState = true;
        if (!IsPostBack)
        {
            this.ReloadTasks(null, EventArgs.Empty);
        }
        else
        {
            CtnlEditTask.CurrentTaskClick += new TaskUpdateHandler(ReloadTasks);
        }
    }
 
Control_EditTask.ascx.cs:
public delegate void TaskUpdateHandler(object sender, EventArgs e);
 
public partial class Control_EditTask : System.Web.UI.UserControl
{
    private int _taskID = 0;
    private TaskUsers _taskUsers = new TaskUsers();
    private Task _task = null;
    private TaskTopics _topics = null;
 
    public event TaskUpdateHandler CurrentTaskClick;
 
    protected void Page_Load(object sender, EventArgs e)
    {
            CurrentTaskClick += new TaskUpdateHandler(this.cmdUpdate_Click);
        
    }
...
    protected void cmdUpdate_Click(object sender, EventArgs e)
    {...}
 
}

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Question by:Unionblitz
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7 Comments
 
LVL 15

Expert Comment

by:jinal
ID: 24830111
Hello ,

Please explain what you want to achive ?
0
 

Author Comment

by:Unionblitz
ID: 24830173
I want to have a aspx page call a method within that aspx page when an event (like a button being pressed) is fired in a user control.

I have a default.aspx page that has a user control.  The user control has some text fields and a button, " btnUpdate".  When the btnUpdate is pressed, I want that user control to update itself, and then I want default.aspx to call a method from within default.aspx (so default.aspx gets updated as well).

Ideas?
0
 
LVL 15

Expert Comment

by:jinal
ID: 24830879
I am not understanding that you want to transfer call event from UserControl to page.

1. ASPX
           -  Has User Control.
                     - On Button Update click in UserControl you want to indicate this update in DEfault.aspx too.

Am i right ?
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Author Comment

by:Unionblitz
ID: 24831146
That's correct- On Button Update click in UserControl should trigger an event in Default.aspx, which will be mapped to a method in Default.aspx...

A user control contains content that needs to refresh other elements on the Default.aspx page.

Ideas?
0
 
LVL 15

Expert Comment

by:jinal
ID: 24831179
Hello ,

Please try attached sample.



/* WebUserControl.ascx */
<%@ Control Language="C#" AutoEventWireup="true" CodeFile="WebUserControl.ascx.cs" Inherits="WebUserControl" %>
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
 
/* WebUserControl.ascx.cs */
 
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
 
public partial class WebUserControl : System.Web.UI.UserControl
{
    public delegate void TaskUpdateHandler(object sender, EventArgs e);
    public event TaskUpdateHandler CurrentTaskClick;
 
    protected void Page_Load(object sender, EventArgs e)
    {
 
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        // Do stuff for button and than fire event.
        Response.Write("This is control event");
        if (CurrentTaskClick != null)
        {
            CurrentTaskClick(sender, e);
        }
    }
}
 
 
/* ASPX PAge */
 
<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>
 
<%@ Register src="WebUserControl.ascx" tagname="WebUserControl" tagprefix="uc1" %>
 
<!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></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    
        <uc1:WebUserControl ID="WebUserControl1" runat="server" />
    
    </div>
    </form>
</body>
</html>
 
/* default.aspx.cs */
 
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
 
public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        WebUserControl1.CurrentTaskClick += new WebUserControl.TaskUpdateHandler(WebUserControl1_CurrentTaskClick);
        if (!Page.IsPostBack)
        {
            this.WebUserControl1_CurrentTaskClick(this.WebUserControl1, EventArgs.Empty);
        }
    }
 
    void WebUserControl1_CurrentTaskClick(object sender, EventArgs e)
    {
        Response.Write("This is in page");
    }
}

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LVL 15

Accepted Solution

by:
jinal earned 1000 total points
ID: 24831186
Try with previous sample .

And i think you need to change one thing in your code and try .

You default.aspx.cs should look like this. As  you are puuting CtnlEditTask.CurrentTaskClick += new TaskUpdateHandler(ReloadTasks); in else it create problem. b'coz viewstate persistes control state not events.

Default.aspx.cs:
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            this.ReloadTasks(null, EventArgs.Empty);
        }
        CtnlEditTask.CurrentTaskClick += new TaskUpdateHandler(ReloadTasks);     
    }
 

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0
 

Author Closing Comment

by:Unionblitz
ID: 31602368
Jinal, thank you for your help!  It took a little tweeking on my end to get the delegate to work, but the code you provided was exactly what I was looking for.
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