How to use Delegates - call a parent function from a Child UserControl

[NightZEN]

I have been reading about using delegates on a few posts here and msdn, but still don't quite get it. Here is my situation: I have a "mother" page add_customer.aspx and a"child" user control add_group.ascx. On the mother page is an "add group" button that makes the the panel inwhich the add_customer control resides VISIBLE=True. On the control, the user can edit the list of groups, or add a new one. After the edit is complete I want to make the panel again VISIBLE=False, as well as refill the "mother" page's dataset and rebind the controls. It seems clear that the correct method is to use a delegate to runa function on the mother page from the child user control, but I am having understanding how. Please help, if you have a moment, or direct me some similar examples.

Thanks

 

[NightZEN]

How about some more info. Here is what i have so far:

In my User Control is a datagrid where you can edit and add records. In the code behind page, I declare a delegate like so:

Public Class add_group
    Inherits System.Web.UI.UserControl
    Private delReturnValue As System.Delegate
    Private intGroup As Integer

...etc.

Then after updating the data, I have tried to invoke the Delegate. As I understand it, this is the User Control's method that does the work to trigger the parent page's PopulateData() method.

Private Sub DataGrid1_UpdateCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles DataGrid1.UpdateCommand
        'Grab edited row for delgate call
        intGroup = e.Item.Cells(1).Text

        'Fill DataSet and identify row to edit
        da_addgroup.Fill(Ds_addgroup)
        Dim str_debug As String = e.Item.Cells(1).Text
        Dim objEditedRow As DataRow = Ds_addgroup.Tables("tbl_customer_group").Rows.Find(e.Item.Cells(1).Text)

        'Cycle through valid "data" cells and put 
        'information back in underlying DataSet
        Dim intCount As Integer
        For intCount = 0 To e.Item.Cells.Count - 1
            If e.Item.Cells(intCount).Controls.Count > 0 Then
                If TypeOf (e.Item.Cells(intCount).Controls(0)) Is TextBox Then
                    ' This appears to be a TextBox-holding "data" cell
                    Dim strValue As String = CType(e.Item.Cells(intCount).Controls(0), TextBox).Text
                    ' Put value (or null if empty) back into relevant DataSet field
                    If strValue = "" Then
                        objEditedRow.Item(DataGrid1.Columns(intCount).SortExpression) = System.DBNull.Value
                    Else
                        objEditedRow.Item(DataGrid1.Columns(intCount).SortExpression) = strValue
                    End If
                End If
            End If
        Next


        ' Update backend data
        da_addgroup.Update(Ds_addgroup)

        ' Deselect DataGrid items and rebind
        With DataGrid1
            .SelectedIndex = -1
            .EditItemIndex = -1
            .DataSource = Ds_addgroup
            .DataBind()
        End With

        'Hide me on the add_customer.aspx page and update the ddl Group Value
        Dim aObj(0) As Object
        aObj(0) = intGroup
        delReturnValue.DynamicInvoke(aObj)


    End Sub

Now, I get an error at the delReturnValue.DynamicInvoke line that says: [Red] "Object reference not set to an instance of an object." [/Red]

On the mother page I declare the delegate class:

Public Class WebForm2
    Inherits System.Web.UI.Page
    Delegate Sub DelGroupsUpdated(ByVal myInt As Integer)

Then, in the Page load I call my subroutine via the Delegate.

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'Put user code to initialize the page here
        If Not Page.IsPostBack Then
            Panel1.Visible = False
            btn_add.Enabled = False
            If GetQueryString("num", Me) = "new" Then
                'Load Defaults for a blank customer
                LoadDefaults()
            Else
                'Load Customer values
                LoadCustomer()
            End If
        End If

        Dim delGroup As New DelGroupsUpdated(AddressOf Me.UpdateGroupAndHide)

    End Sub

    Private Sub UpdateGroupAndHide(ByVal intGroup As Integer)
        'load dataset
        da_customer.SelectCommand.Parameters("@cust_num").Value = GetQueryString("num", Me)
        da_customer.Fill(Ds_customer_update)
        da_engineers.Fill(Ds_customer_update)
        da_country.Fill(Ds_customer_update)
        da_group.Fill(Ds_customer_update)
        da_states.Fill(Ds_customer_update)
        'rebind customere group ddl
        ddl_cust_group.DataBind()
        'select the new or updated value
        Me.ddl_cust_group.SelectedIndex = intGroup
        'Hide the panel
        Panel1.Visible = False
    End Sub

I am obviously not getting this right. Any help you have to offer would be great! (and please go easy on me, this is my first asp.net project...)