Finding controls in nested listviews

I'm building a collapsible grouping grid using Matt Berseth's example from mattberseth.com/blog/2008/01/building_a_grouping_grid_with.html

It has an inner listview "lvInner" nested in an outer listview "lvOuter". I'm trying to access a textbox in lv_Inner using

Protected Sub lvInner_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ListViewItemEventArgs) Handles lvInner.ItemDataBound

    If e.Item.ItemType = ListViewItemType.DataItem Then

     Dim tb As TextBox = TryCast(e.Item.FindControl("lvOuter").FindControl("lvInner").FindControl("TextBox1"), TextBox)
           ' Do something to TextBox1

     End If
EndSub

I get an "Object reference not set to an instance of an object" error on line Dim tb.

From stackoverflow

• You need to simply do e.Item.FindControl("textbox"), e.Item is already scoped to the the proper listView.

  Protected Sub lvInner_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ListViewItemEventArgs) Handles lvInner.ItemDataBound
  
  If e.Item.ItemType = ListViewItemType.DataItem Then
  
   Dim tb As TextBox = TryCast(e.Item.FindControl("TextBox1"), TextBox)
         ' Do something to TextBox1
  
   End If
  EndSub
  

• FindControl is handy, but not recursive.

  If you have deep nesting of controls on a page, you might need to recursively search through the control hierarchy of the page to find the control you need.

  write your own method...

  C# example: (Convert using any free VBtoC# online tool)

  public static System.Web.UI.Control FindControlFromTop(System.Web.UI.Control start, string id, System.Web.UI.Control exclude)
       {
        System.Web.UI.Control foundControl;
  
        if (start != null && id != null)
        {
         foundControl = start.FindControl(id);
  
         if (foundControl != null)
          if(foundControl.ID.Equals(id))
           return foundControl;
  
         foreach (System.Web.UI.Control control in start.Controls)
         {
          if (control != exclude)
           foundControl = FindControlFromTop(control, id, null);
  
          if (foundControl != null)
           if (foundControl.ID.Equals(id))
            return foundControl;
         }
        }
  
        return null;
       }
  

  FlySwat : Two things... He doesn't need recursion as e.Item is already on the inner list (look at his code)...and two, you can make your recursive method about 10 lines shorter.