inherited DataGrid failed to render

[Frank]

Hi all,

I want to derive a class from DataGrid so that I can have
a label on the top.
But when I tried to add the control to my form, I got an
error "Specified cast is not valid" on the line:
MyBase.Render(w) in the Render function.

Thanks a lot.
Frank

Here is my simple code.

Private Sub Page_Load(ByVal sender As System.Object,
ByVal e As System.EventArgs) Handles MyBase.Load

Dim g As New Grid2
Me.Form1.Controls.Add(g)
End Sub
Public Class Grid2
Inherits DataGrid
Dim _label1 As New Label

Protected Overrides Sub OnInit(ByVal e As EventArgs)
Me.Controls.Add(Me._label1)
End Sub
Public ReadOnly Property Label1() As Label
Get
Return Me._label1
End Get
End Property
Protected Overrides Sub Render(ByVal w As
HtmlTextWriter)
MyBase.Render(w)
Me._label1.RenderControl(w)
End Sub
End Class

 

[chanmmn]

You cannot do that I think you need to create your own user control.

chanmm

 

[Scott Allen]

Hi Frank:

You can inherit from a DataGrid.

In this case though, I think you might want to look at hooking the
ItemCreated event, look for when the grid is creating a header
section, and add an extra row to the data grid with your text.

This article demonstrates many tricks you can use:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndive/html/data01102002.asp