Filter By ListTextField for GridDropDownColumn

The built-in GridDropDownColumn is filtered by its ListValueField when the default filtering feature of the control is used. RadGrid does not include any support for filtering by ListTextField instead.

This limitation is because the filtering mechanism relies on the DataField of the filtered column and for GridDropDownColumn this property specifies the mapping field in the drop-down source. (For more information about the properties of GridDropDownColumn, see Customize/Configure GridDropDownColumn).If you want to filter by ListTextField, your current options are:

• use a hidden GridBoundColumn (with Display = false). Add an ItemCommand event handler that catches filter commands from the dropdown column and substitutes a filter command from the GridBoundColumn instead:

<telerik:GridDropDownColumn UniqueName="CategoryddColumn" ListTextField="CategoryName"
  HeaderText="Category name" ListValueField="CategoryID" DataField="CategoryID" DataSourceID="dataSourceCategories">
</telerik:GridDropDownColumn>
<telerik:GridBoundColumn DataField="CategoryName" HeaderText="CategoryName" SortExpression="CategoryName"
  UniqueName="CategoryName" Display="false">
</telerik:GridBoundColumn>

protected void RadGrid1_ItemCommand(object source, GridCommandEventArgs e)
{
    if (e.CommandName == RadGrid.FilterCommandName)
    {
        Pair command = (Pair)e.CommandArgument;
        if (command.Second.ToString() == "CategoryddColumn")
        {
            e.Canceled = true;
            GridFilteringItem filter = (GridFilteringItem)e.Item;
            ((filter["CategoryName"].Controls[0]) as TextBox).Text = ((filter["CategoryddColumn"].Controls[0]) as TextBox).Text;
            command.Second = "CategoryName";
            filter.FireCommandEvent("Filter", new Pair(command.First, "CategoryName"));
        }
    }
}
protected void RadGrid1_ItemDataBound(object sender, GridItemEventArgs e)
{  
    if (e.Item is GridFilteringItem)
    {  
        GridFilteringItem item = e.Item as GridFilteringItem;
        ((item["CategoryddColumn"].Controls[0]) as TextBox).Text = ((item["CategoryName"].Controls[0]) as TextBox).Text;
    }
}

Protected Sub RadGrid1_ItemCommand(ByVal source As Object, ByVal e As GridCommandEventArgs) Handles RadGrid1.ItemCommand
    If e.CommandName = RadGrid.FilterCommandName Then
        Dim command As Pair = CType(e.CommandArgument, Pair)
        If command.Second.ToString = "CategoryddColumn" Then
            e.Canceled = True
            Dim filter As GridFilteringItem = CType(e.Item, GridFilteringItem)
 CType(filter("CategoryName").Controls(0), TextBox).Text = CType(filter("CategoryddColumn").Controls(0), TextBox).Text   
            command.Second = "CategoryName"
            filter.FireCommandEvent("Filter", New Pair(command.First, "CategoryName"))
        End If
    End If
End Sub
Protected Sub RadGrid1_ItemDataBound(ByVal sender As Object, ByVal e As GridItemEventArgs) Handles RadGrid1.ItemDataBound
    If TypeOf e.Item Is GridFilteringItem Then
        Dim item As GridFilteringItem = TryCast(e.Item, GridFilteringItem)
        TryCast(item("CategoryddColumn").Controls(0), TextBox).Text = TryCast(item("CategoryName").Controls(0), TextBox).Text
    End If
End Sub

• Use GridTemplateColumn instead of GridDropDownColumn. You can add a DropDownList in its EditItemTemplate to simulate the GridDropDownColumn.

As RadGrid can only be filtered by fields in its DataSource, these work arounds are only valid when the ListTextField of the GridDropDownColumn is a field from the control's assigned data source.