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Raise Event Parent Form to User Control

codequest
codequest asked
on
Medium Priority
2,513 Views
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!
Comment
Watch Question

Wait, are you trying to get the usercontrol to handle an event? from the parent page?

Just to clarify.

Author

Commented:
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.

Commented:
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

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Author

Commented:
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!
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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