How to bind a hash to RadFilterCustomEditors.RadFilterDropDownEditor for choices.

[Matthew]

I am using a Filter control that is never bound to a grid or list view.  I have a set of fields that are passed into my user control, and I iterate over those fields to build the FieldEditor controls that I need in my Filter control.  This works well for all the standard FieldEditor types, (ie. boolean, numeric, text) However, I am having trouble populating the choices for editors of type RadFilterCustomEditors.RadFilterDropDownEditor  I am using the following code called from my user controls pre render event.

Dim choices As Dictionary(Of String, String) = New Dictionary(Of String, String)()
choices.Add("Yes", "Yes")
choices.Add("No", "No")

Dim field As RadFilterCustomEditors.RadFilterDropDownEditor = New RadFilterCustomEditors.RadFilterDropDownEditor()
field.DataSourceID = "????" 'What would go here?
field.DataValueField = "Key"                       
field.DataTextField = "Value"

QuestionFilter.FieldEditors.Add(field)
field.FieldName = question.Id                       
field.DisplayName = question.Description

obviously this is incomplete and doesn't work.  I have tried creating a FilterChoice object with a display and value property and binding a list of those to an objectdatasource, but ran into issues there with strings being in the wrong format, and that really isn't the best implementation anyway, so I have abandoned it for the time being.

So my question is in a nutshell, how do I build a list of choices, and bind it to a RadFilterCustomEditors.RadFilterDropDownEditor at run time without being tied to a grid?

[Matthew]

This is my latest implementation using an ObjectDataSource. Here is the source for my user control

ASPX

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="QuestionFilter.ascx.vb" Inherits="Reporting_QuestionReport_UserControls_QuestionFilter" %>
<asp:Panel id="QuestionFilterPanel" runat="server">
    <telerik:RadFilter ID="QuestionFilter" runat="server" ShowApplyButton="false" ShowLineImages="true"/></asp:Panel>

Code Behind

Imports Telerik.Web.UI

Namespace Reporting.QuestionReport.UserControls
Public Class FilterChoice
Private _displayText As String
Public Property DisplayText() As String
Get
Return _displayText
End Get
Set(ByVal value As String)
_displayText = value
End Set
End Property

Private _valueText As String
Public Property ValueText() As String
Get
Return _valueText
End Get           
Set(ByVal value As String)
_valueText = value
End Set
End Property

Public Sub New(ByVal value As String, ByVal display As String)
_displayText = display
_valueText = value
End Sub

Public Function GetYesNoFilterChoiceCollection() As IEnumerable(Of FilterChoice)
Dim list As List(Of FilterChoice) = New List(Of FilterChoice)
list.Add(New FilterChoice("Yes", "Yes"))
list.Add(New FilterChoice("No", "No"))
Return list
End Function
End Class
End Namespace

Partial Class Reporting_QuestionReport_UserControls_QuestionFilter
Inherits ReportParameterSelectorUserControl

Private Const QuestionType_YesNo As String = "Yes/No"
Private Const QuestionType_Number As String = "Number"
Private Const QuestionType_Date As String = "Date"
Private Const QuestionType_SingleAnswer As String = "Single Answer"
Private Const QuestionType_MultiAnswer As String = "Multi Answer"
Private Const QuestionType_AggregateCompliance As String = "Aggregate Compliance"

Public Property AvailableQuestions() As QuestionCollection
Get
Return CType(ViewState("AvailableQuestions"), QuestionCollection)
End Get
Set(ByVal value As QuestionCollection)
ViewState("AvailableQuestions") = value
End Set
End Property

Private _yesNoDatasource As ObjectDataSource

Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init

_yesNoDatasource = New ObjectDataSource()
_yesNoDatasource.ID = "YesNoChoices"
_yesNoDatasource.TypeName = "Reporting.QuestionReport.UserControls.FilterChoice"
_yesNoDatasource.SelectMethod = "GetYesNoFilterChoiceCollection"

End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

End Sub
Protected Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender

AddQuestionsToQuestionFilter()

End Sub

Private Sub AddQuestionsToQuestionFilter()

If Not AvailableQuestions Is Nothing Then

QuestionFilter.ExpressionPreviewPosition = RadFilterExpressionPreviewPosition.Bottom
QuestionFilter.FieldEditors.Clear()
For Each question In AvailableQuestions
Select Case question.QuestionType.Description
Case QuestionType_YesNo

Dim field As RadFilterCustomEditors.RadFilterDropDownEditor = New RadFilterCustomEditors.RadFilterDropDownEditor()
field.DataSourceID = "YesNoChoices"
field.DataValueField = "DisplayText"
field.DataTextField = "ValueText"

QuestionFilter.FieldEditors.Add(field)
field.FieldName = question.Id
field.DisplayName = question.Description

Case QuestionType_Number
Dim field As RadFilterNumericFieldEditor = New RadFilterNumericFieldEditor()

QuestionFilter.FieldEditors.Add(field)
field.FieldName = question.Id
field.DisplayName = question.Description

Case QuestionType_Date
Dim field As RadFilterDateFieldEditor = New RadFilterDateFieldEditor()

QuestionFilter.FieldEditors.Add(field)
field.FieldName = question.Id
field.DisplayName = question.Description

'Case QuestionType_SingleAnswer
'    field = New RadFilterCustomEditors.RadFilterDropDownEditor()
'Case QuestionType_MultiAnswer
'    field = New RadFilterCustomEditors.RadFilterDropDownEditor()
'Case QuestionType_AggregateCompliance
End Select
Next
End If
End Sub
End Class

I'm recieving the following error when trying to add a filter expression to the filter control at run time

FieldEditors collection is empty.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: FieldEditors collection is empty.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[NullReferenceException: FieldEditors collection is empty.] Telerik.Web.UI.RadFilterDataFieldEditorCollection.System.Collections.Generic.IList<Telerik.Web.UI.RadFilterDataFieldEditor>.get_Item(Int32 index) +116 Telerik.Web.UI.RadFilter.AddChildExpression(RadFilterGroupExpressionItem groupItem, Boolean isGroup) +83 Telerik.Web.UI.RadFilterCommandEventArgs.ExecuteCommand(Object source) +134 Telerik.Web.UI.RadFilter.OnBubbleEvent(Object source, EventArgs args) +139 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37 Telerik.Web.UI.RadFilterExpressionItem.OnBubbleEvent(Object source, EventArgs args) +77 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37 System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e) +125 System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +169 System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +9 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +176 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

If I don't have any drop down field editors the control works just fine.  I think this has to do with the page life cycle, and when I am setting up the field editors, however, since I have to recieve the available fields from the Parent page, and the property is set after page load fires I think I have to use the PreRender event. 

I'm at a loss, any help you can provide is appreciated.

[Matthew]

solved by implementing the RadFilterDropDownFieldEditor found here:

http://www.telerik.com/community/forums/aspnet-ajax/filter/error-when-building-custom-radfilterdatafieldeditor.aspx