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DropDownListBoundColumn for ASP.Net Datagrid

written by Mark Rowlinson - Last updated Feb 2006

Use code such as the following to add the column to your grid:

 
 
Dim t As New System.Web.UI.WebControls.TemplateColumn 
With t 
    .HeaderText = \"Col Header\" 
    .ItemTemplate = New MyDropDownTemplate(\"DataField\", True) 'displaying items is always read only
    .EditItemTemplate = New MyDropDownTemplate(\"ActionRequired\", False) 
    .Visible = True 
End With 
MyDataGrid.Columns.Add(t) 
 
 

The following class is the implemantation of ITemplate that creates the dropdown column. This example is a column that has true/false values only.

 
Public Class MyDropDownTemplate 
    Implements ITemplate 
     
    Private m_data As String 
    Private m_read As Boolean 
     
    Public Sub New(ByVal DataSource As String, ByVal [ReadOnly] As Boolean) 
        m_data = DataSource 
        m_read = [ReadOnly] 
    End Sub 
     
    Public Sub InstantiateIn(ByVal container As System.Web.UI.Control) Implements System.Web.UI.ITemplate.InstantiateIn 
        If m_read Then 
            Dim l As New System.Web.UI.WebControls.Literal 
            AddHandler l.DataBinding, AddressOf Me.DataBind 
            container.Controls.Add 
        Else 
            Dim dl As New System.Web.UI.WebControls.DropDownList 
            AddHandler dl.DataBinding, AddressOf Me.DataBind 
             'now add the items to the list
            dl.Items.Add(\"True\") 
            dl.Items.Add(\"False\") 
            container.Controls.Add(dl) 
        End If 
    End Sub 
     
    Private Sub DataBind(ByVal sender As System.Object, ByVal e As System.EventArgs) 
        If m_read Then 
            Dim l As System.Web.UI.WebControls.Literal = CType(sender, System.Web.UI.WebControls.Literal) 
            Dim container As DataGridItem = CType(l.NamingContainer, DataGridItem) 
            Dim DRV As DataRowView = CType(container.DataItem, DataRowView) 
            l.Text = CType(DRV(m_data), String) 
        Else 
            Dim dl As System.Web.UI.WebControls.DropDownList = CType(sender, System.Web.UI.WebControls.DropDownList) 
            Dim container As DataGridItem = CType(dl.NamingContainer, DataGridItem) 
            Dim DRV As DataRowView = CType(container.DataItem, DataRowView) 
             'determine the selected item
            If CType(DRV(m_data), String).ToLower = \"true\" Then 
                dl.SelectedIndex = 0 
            Else 
                dl.SelectedIndex = 1 
            End If 
        End If 
         
    End Sub 
     
     
End Class