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Raise Event Parent Form to User Control

Posted on 2006-11-06
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Last Modified: 2008-01-09
I'd like to raise an event in a user control and handle it on the parent form.  I've gotten this to work in communicating from the parent form to the user control.  But I don't know how, in the user control, to declare the event on the parent form.   And I can't use a derived class/base class because based events can't be raised from derived...

So, here's a workaround, but it doesn't work....the event that is raised is not being picked up by the user control....

===================MAIN PAGE ===========================
<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Main.aspx.vb" Inherits="Main" %>

<%@ Register Src="UC1.ascx" TagName="UC1" 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>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
            <uc1:UC1 ID="UC1_1" runat="server" />
            <asp:Button ID="Button1" runat="server" Text="Button" /></div>
    </form>
</body>
</html>

‘===================MAIN PAGE CODE BEHIND ================

Partial Class Main
Inherits System.Web.UI.Page

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim exeDM As New EH
exeDM.SendEvent()
End Sub
End Class
‘===================USER CONTROL ================

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="UC1.ascx.vb" Inherits="UC1" %>

Partial Class UC1
Inherits System.Web.UI.UserControl
Private EH1 As New EH
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
      AddHandler EH1.Event2, AddressOf ReceiveEvent
End Sub
Private Sub ReceiveEvent(ByVal sender As Object, ByVal e As CommandEventArgs)
            MsgBox("received")
End Sub
End Class

‘================  HELPER CLASS =====================

Imports Microsoft.VisualBasic
Public Class EH
Public Event Event2 As CommandEventHandler
Public Sub SendEvent()
Dim args As New CommandEventArgs("Event2", "EventMessage")
RaiseEvent Event2(Me, args)
End Sub
End Class

‘=================================================


Any guidance on this would be appreciated.

Thanks!
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Comment
Question by:codequest
  • 2
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5 Comments
 
LVL 4

Expert Comment

by:darkpriest
ID: 17886382
Wait, are you trying to get the usercontrol to handle an event? from the parent page?

Just to clarify.
0
 
LVL 2

Author Comment

by:codequest
ID: 17886669
Thanks for your message.  Yes, I want to get the user control to handle an event from the parent page.  

Purpose:  there is a control on the usercontrol that I want to modify based on a click event from the parent page.  

Since posting this, I found a way to do this by using a recursive "FindControl"-type function to locate the control that I want to modify.

However, I was hoping to use the event communication technique in order to keep the code a little cleaner, as I will be doing something similar in several other instances.

May be a little academic, but I'd like to see if I can get anything back from my several hours of head-wringing on this one... :O)

If the event communication from parent to user control seems highly unlikely to succeed or unusual as an approach, it would be OK to know that, too.

0
 
LVL 10

Accepted Solution

by:
jnhorst earned 500 total points
ID: 17886818
You can create a property accessor for the control in the user control.

Let's say you have a textbox (named txtSomeText as an example) in the user control and you want to manipulate it based on a button click event from elsewhere on the page.  In your *user control*, do this in the codebehind:

Public ReadOnly Property SomeText() As TextBox
      Get
            Return Me.txtSomeText
      End Get
End Property

Then in your button click event you can get to the textbox like this:

Me.UserControlName.SomeText.Text = "some value here"

John
0
 
LVL 2

Author Comment

by:codequest
ID: 17890626
Thanks for input.   That works great, and does a much better job of addressing this particular need.  I also see that I can access the entire control on the user control with a read only property, and manipulate the control properties through that call.   Based on this I'm going to drop the request for an "event communication" approach.

Big help!  Grazie!
0
 
LVL 4

Expert Comment

by:darkpriest
ID: 17903334
Bugger, I guess i should pay more attention.

I have an example of dynamic user control creation that is called back and forth between userControls and Parent Pages.
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