Add an extra header to an ASP.NET DataGrid

• Download source and demo project - 22 Kb

Introduction

This article explains how to add an extra header item to a standard ASP.NET DataGrid.

Using the code

The code is pretty simple ,the grid is build using a DataGridTable object ,all we have to do is to add a DataGridItem to the rows collection in the CreateControlHierarchy method of our custom grid.
Now I'll let the code talk:

    Protected Overrides Sub CreateControlHierarchy(ByVal useDataSource As Boolean)
        MyBase.CreateControlHierarchy(useDataSource)
        If Not ShowExtraHeader Then Return
        If Controls.Count > 0 Then
            'get all grid's items (rows)
            Dim rows As TableRowCollection = DirectCast(Controls(0), Object).Rows
            'create extra header item
            Dim extraHeaderRow As DataGridItem = CreateItem(-1, -1, ListItemType.Header)
            'set an id that will identify it in ItemCreated event
            extraHeaderRow.ID = "extraheader"
            'create an event attached to our item
            Dim extraHeaderRowArgs As New DataGridItemEventArgs(extraHeaderRow)
            'call ItemCreated event
            OnItemCreated(extraHeaderRowArgs)
            'finally add the extra header item to the items's collection
            rows.AddAt(0, extraHeaderRow)
        End If
    End Sub

    Private Sub g_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles g.ItemCreated
        If e.Item.ItemType = ListItemType.Header Then
            If e.Item.ID = "extraheader" Then

                Dim refreshCell As New TableCell
                refreshCell.ColumnSpan = 2
                refreshCell.HorizontalAlign = HorizontalAlign.Center
                Dim btnRefresh As New Button
                btnRefresh.Text = "Refresh"
                refreshCell.Controls.Add(btnRefresh)
                AddHandler btnRefresh.Click, AddressOf btnRefresh_Click

                Dim parentsCell As New TableCell
                parentsCell.ColumnSpan = 2
                parentsCell.HorizontalAlign = HorizontalAlign.Center
                parentsCell.Text = "Parents"

                e.Item.Cells.Add(refreshCell)
                e.Item.Cells.Add(parentsCell)
            End If
        End If
    End Sub

That's all!Check the demo project to see all the bits.

History

Dec 10, 2005 - Version 1.0.