RIA Not Loading Child Entities With RIA & Silverlight - silverlight

Question

I am having difficulty loading some child attributes of a given entity. I have managed to load child entities on other objects, but not this one. To add to the frustration, the child entities I am trying to load are referenced from another Entity, and from this they work fine...
My code is as follows.
ViewWasteApplication Page
Protected Overrides Sub OnNavigatedTo(ByVal e As System.Windows.Navigation.NavigationEventArgs)
If NavigationContext.QueryString.ContainsKey("ID") Then
' load an existing record - edit mode
Context.Load(Context.GetWasteApplicationsByIDQuery(Int32.Parse(NavigationContext.QueryString("ID").ToString())),
AddressOf wasteApplicationLoaded, Nothing)
Else
MessageBox.Show("Application not found")
End If
End Sub
This calls GetWasteApplicationsByID - which is as follows:
Public Function GetWasteApplicationsByID(ByVal query As Int32) As IQueryable(Of WasteApplication)
Dim result = Me.ObjectContext.WasteApplications.Include("CurrentlyWith") _
.Include("Packaging") _
.Include("WasteStream") _
.Where(Function(f) f.ID = query)
Return result
End Function
The WasteApplication is being returned, but neither of the 3 child entities are appearing.
I have created a MetaData class for this WasteApplication, as follows:
<MetadataTypeAttribute(GetType(WasteApplications.WasteApplicationsMetaData))> _
Partial Public Class WasteApplications
Friend NotInheritable Class WasteApplicationsMetaData
'Metadata classes are not meant to be instantiated.
Private Sub New()
MyBase.New()
End Sub
Public Property ID As Integer
Public Property RequestedByName As String
Public Property RequestedByExtension As String
Public Property CARQRequired As Boolean
Public Property OriginOfMaterialID As Integer
Public Property Comments As String
Public Property MaterialName As String
Public Property PackagingID As Integer
Public Property FacilityPath As String
Public Property ProcessStatus As String
Public Property DateSubmitted As DateTime
Public Property RequestedByUsername As String
Public Property CurrentlyWithID As Integer
Public Property WasteStreamID As Integer
<Include()>
Public Property WasteStream As WasteStreams
<Include()>
Public Property Packaging As Packaging
End Class
End Class
Can anyone see anything wrong with this? I load the same two child objects on another page, and these seem to load just fine. The code for this is as follows:
View Chemical Application (This works)
Protected Overrides Sub OnNavigatedTo(ByVal e As System.Windows.Navigation.NavigationEventArgs)
Context.Load(Context.GetChemicalApplicationsByIDQuery(Int32.Parse(NavigationContext.QueryString("ID"))),
AddressOf wasteApplicationLoaded, Nothing)
End Sub
With the RIA function as follows:
Public Function GetChemicalApplicationsByID(ByVal query As Int32) As IQueryable(Of ChemicalApplication)
Return Me.ObjectContext.ChemicalApplications.Include("Chemical") _
.Include("ProcessStatus") _
.Include("PlanningApprover") _
.Include("FacilitiesApprover") _
.Include("MaintenanceApprover") _
.Include("PPCPermit") _
.Include("DischargeConsent") _
.Include("Facility") _
.Include("Packaging") _
.Include("WasteStream") _
.Where(Function(f) f.ID = query)
End Function
Any suggestions?
NOTE: I have not posted any of the XAML bindings, as I have confirmed via debugging that the source entities do not contain the child data, so therefore binding will not be an issue.
I am using Silverlight 4 with Entity Framework 4.

Answer 1

You will need to create metadata classes for the entities you wish to include and mark the fields with the [Include] attribute.
[MetadataTypeAttribute(typeof(Client.ClientMetadata))]
public partial class Client
{
internal sealed class ClientMetadata
{
private ClientMetadata()
{
}
[Required(ErrorMessage="You must enter a client name")]
public string Name;
[Include]
public EntityCollection<Contact> Contacts;
[Include]
public Employee Employee;
[Include]
public BillTo BillTo;
}
}
See RIA Services and relational data for more.

Answer 2

You need to do the 2 following things in order for this to work:
a) Add the include parameter in a metadata class (as DaveB proposed)
b) on the domain service queries (server side) add the include directive - Me.ObjectContext.WasteApplications.Include("CurrentlyWith")

Answer 3

I managed to solve the issue, you need to load the respective entities into the datacontext as well as loading the linked entity. i.e in my case I need to add:
Context.Load(Context.GetWasteStreamsQuery())
Context.Load(Context.GetPackagingQuery())
so that the linked child entities exist. My full onNavigate therefore looks like this:
Protected Overrides Sub OnNavigatedTo(ByVal e As System.Windows.Navigation.NavigationEventArgs)
If NavigationContext.QueryString.ContainsKey("ID") Then
Context.Load(Context.GetWasteApplicationsByIDQuery(Int32.Parse(NavigationContext.QueryString("ID").ToString())),
AddressOf wasteApplicationLoaded, Nothing)
Context.Load(Context.GetWasteStreamsQuery())
Context.Load(Context.GetPackagingQuery())
Else
MessageBox.Show("Application not found")
End If
End Sub