Danny Simmons has posted the code for his EntityBag class (aka “Perseus”) on the MSDN Code Gallery Site here.

I grabbed it last night and set up a test project so that I could see what the payload looks like.

The results of that test are in this blog post, Testing out the EntityBag.

There were a few tricks for getting the web service to work properly if you are not familiar with using WCF, so I wanted to show that code.

I started by creating a DLL library just to host my EDM.

Then I created a WCF Service. The WCF service references the EDM project and the Perseus project.

I created my interface along with a HelloWorld op which is always handy for testing.

<OperationContract()> _
   <ServiceKnownType(GetType(SalesOrderHeader))> _
   <ServiceKnownType(GetType(SalesOrderDetail))> _
 Function GetData(ByVal value As Integer) As Perseus.EntityBag(Of SalesOrderHeader)

 <OperationContract()> _
 Function HelloWorld() As String

There’s something critical in the above example. Without the ServiceKnownType declarations for the SalesOrderHeader and SalesOrderDetail, you will get an error when the service tries to serialize the return data. You can read more about this here. In C#, you use typeof() where I have GetType().

Then I created the methods that implement these interfaces in my Service class.

 Public Function GetData(ByVal value As Integer) As Perseus.EntityBag(Of SalesOrderHeader) _
  Implements IService1.GetData
    Using aw As New awEntities
      Dim order = (From ord In aw.SalesOrderHeaders.Include(“SalesOrderDetails”) _
                  Where ord.SalesOrderID = value _
                  Select ord).First
      Return aw.CreateEntityBag(Of SalesOrderHeader)(order) 
    End Using 
  End Function

  Public Function HelloWorld() As String Implements IService1.HelloWorld
    Return “Hello World”
  End Function

Next is the ConsoleApp that will call the service.

Nothing fancy here, I make a service reference to the service in the project and a references to the Perseus project and the project that hosts my EDM. In code, I instantiate the service, then call HelloWorld to make sure things are wired up properly and finally the GetData method passing in an  OrderNumber. Not sure why I didn’t use orderid. Just too focused on other things at the time!

   Dim ordEntityBag As Perseus.EntityBag(Of SalesOrderHeader)
   Dim svc = New ServiceReference1.Service1Client
   Dim s = svc.HelloWorld
   Try
     ordEntityBag = svc.GetData(71780)
   Catch timeout As TimeoutException
     svc.Abort()
   Catch commException As System.ServiceModel.CommunicationException
     svc.Abort()
   End Try

This returns an unmodified object. Next I wanted to see what it looked like if it was modified so I just added some code into the GetData method in the service.

Public Function GetData(ByVal value As Integer) As Perseus.EntityBag(Of SalesOrderHeader) Implements IService1.GetData
  Using aw As New awEntities
    Dim order = (From ord In aw.SalesOrderHeaders.Include(“SalesOrderDetails”) _
                Where ord.SalesOrderID = value _
                Select ord).First
    order.Comment = “12345”
    Dim i As Int32
    For Each sd As SalesOrderDetail In order.SalesOrderDetails
      sd.OrderQty = 25
      If i = 10 Or i = 12 Then
        sd.OrderQty = 0
      End If
      i += 1
    Next
    Dim sod = From s In order.SalesOrderDetails Where s.OrderQty = 0 Select s
    For i = sod.Count To 1 Step -1
      aw.DeleteObject(sod(i – 1))
    Next 
    Return aw.CreateEntityBag(Of SalesOrderHeader)(order)

  End Using

End Function

Here’s what the EntityBag for this looks like when it gets back to the client:

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