Multiple dropdownlis filters

[Andy]

I am trying to set up a RadGrid with multiple dropdownlist filters but I get an ArgumentOutOfRangeException on the MyCustomFilteringColumn 

Here is code from the MyCustomFilteringColumn  
 :
       Protected Overloads Overrides Sub SetupFilterControls(ByVal cell As TableCell)
            MyBase.SetupFilterControls(cell)
            cell.Controls.RemoveAt(0)
            Dim list As New DropDownList()
            list.ID = "list" + Me.DataField
            list.AutoPostBack = True
            AddHandler list.SelectedIndexChanged, AddressOf list_SelectedIndexChanged
            cell.Controls.AddAt(0, list)
            cell.Controls.RemoveAt(1)
            list.DataTextField = Me.DataField
            list.DataValueField = Me.DataField
            list.DataSource = _listDataSource
            list.DataBind()
        End Sub

My RadGrid columns are setup like the below (here is one of the many that I have): 

         <custom:MyCustomFilteringColumn DataField="AssessmentID" FilterControlAltText="Filter AssessmentID column"
             FilterControlWidth="80px" HeaderStyle-Width="80px" ItemStyle-Width="80px" ItemStyle-ForeColor="Black"
                                                HeaderStyle-Wrap="true" AutoPostBackOnFilter="true" CurrentFilterFunction="Contains"
                                                ShowFilterIcon="false" HeaderText="Assessment ID" SortExpression="AssessmentID"
                                                UniqueName="AssessmentID" />


Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        For Each column As GridBoundColumn In RadGrid1.MasterTableView.Columns
            If TypeOf column Is MyStuff.MyCustomFilteringColumn Then
                CType(column, MyStuff.MyCustomFilteringColumn).ListDataSource = GetFilterTable(column.DataField)
            End If
        Next
end sub

    Private Function GetFilterTable(ByVal Field As String) As DataTable
        Dim strConnection As String = ConfigurationManager.ConnectionStrings("PKLConnectionString").ConnectionString
        Dim objConnection As New SqlConnection(strConnection)
        Dim SQLCmd As New SqlCommand() 'The SQL Command
        objConnection.ConnectionString = strConnection     'Set the Connection String
        objConnection.Open() 'Open the connection
        SQLCmd.Connection = objConnection 'Sets the Connection to use with the SQL Command
        Dim dt As New DataTable
        Dim adapter As SqlDataAdapter
        adapter = New SqlDataAdapter("SELECT distinct [" + Field + "] FROM tblAssessment", objConnection)
        objConnection.Open()
        Try
            adapter.Fill(dt)
        Finally
            objConnection.Close()
        End Try
        Return dt
    End Function

Error:
System.ArgumentOutOfRangeException was unhandled by user code
  Message=Specified argument was out of the range of valid values.
Parameter name: index
  ParamName=index
  Source=System.Web
  StackTrace:
       at System.Web.UI.ControlCollection.get_Item(Int32 index)
       at System.Web.UI.ControlCollection.RemoveAt(Int32 index)
       at MyStuff.MyCustomFilteringColumn.SetupFilterControls(TableCell cell) in D:\PKLQMW AT 04 05 2012\PKL_QMW\App_Code\MyCustomFilteringColumn.vb:line 33
       at Telerik.Web.UI.GridColumn.InitializeCell(TableCell cell, Int32 columnIndex, GridItem inItem)
       at Telerik.Web.UI.GridBoundColumn.InitializeCell(TableCell cell, Int32 columnIndex, GridItem inItem)
       at Telerik.Web.UI.GridItem.Initialize(GridColumn[] columns)
       at Telerik.Web.UI.GridItem.SetupItem(Boolean dataBind, Object dataItem, GridColumn[] columns, ControlCollection rows)
       at Telerik.Web.UI.GridTableView.CreateFilteringItem(Boolean useDataSource, GridColumn[] copiedColumnSet, GridTHead thead)
       at Telerik.Web.UI.GridTableView.CreateControlHierarchy(Boolean useDataSource)
       at Telerik.Web.UI.GridTableView.CreateChildControls(IEnumerable dataSource, Boolean useDataSource)
       at System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable data)
       at System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable data)
       at System.Web.UI.DataSourceView.Select(DataSourceSelectArguments arguments, DataSourceViewSelectCallback callback)
       at System.Web.UI.WebControls.DataBoundControl.PerformSelect()
       at Telerik.Web.UI.GridTableView.PerformSelect()
       at System.Web.UI.WebControls.BaseDataBoundControl.DataBind()
       at Telerik.Web.UI.GridTableView.DataBind()
       at Telerik.Web.UI.RadGrid.DataBind()
       at System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound()
       at System.Web.UI.WebControls.CompositeDataBoundControl.CreateChildControls()
       at System.Web.UI.Control.EnsureChildControls()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Control.PreRenderRecursiveInternal()
       at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
  InnerException: 

[Pavlina]

Hi Andy,

I am afraid we cannot determine the cause of the issue based on the supplied information. However,  I would suggest that you define FilterTemplate for the columns in question:

http://demos.telerik.com/aspnet-ajax/grid/examples/programming/filtertemplate/defaultcs.aspx

This can be done with little or no custom code, and allows for the same degree of flexibility as the custom column.

Greetings,
Pavlina
the Telerik team