How to use default CommandButtonsVisibility with Dataform, WCF RIA and POCO Entites?

Question

I have a Silverlight project (in VB), which uses a (WCF RIA) Domain Service, which uses POCO Entities. I'm displaying the data with a DataForm. My Domain Service has InsertUser, UpdateUser, DeleteUser-methods (correctly) specified. CommandButtonsVisibility is not set (so I guess it has default values).

However, the Commit-Button is not visible (it's not only disabled, it's not even there). When I set CommandButtonsVisibility=All I can use the edit button and it is working (changes are saved in db). I would like to use the default behavior though.

I recognized the DataForm automatically shows or hides the buttons if the CRUD-methods are written or not written in the Domain Service (I tested it with my Delete-methods).

What am I doing wrong, are my Update-methods not defined correctly? This is how they look like:

Public Sub UpdateUser(ByVal user As User)
     '... update the user
End Sub

For the C#-users:

public void UpdateUser(User user)
     //... update the user
End Sub

Answer 1

First thing is first. The DataForm is the buggiest piece of code I've ever encountered in my life. It was mainly designed to be used as a Child view to a DataGrid, in a Master/Child type of a view. And I guess they only tested it with the unmaintainable drap & drop code that's generate, which you see a lot in the intro videos.

Let's get to your problem now: The most common reason for this is that you're not binding your DataForm to the correct backing data store. If you're binding to a single item, then you're pretty much out of luck. Just implement your own OK and Cancel buttons. But if you're working against a collection, than make sure it implements ICollectionView. (You may get lucky with ObservableCollection as well.)

If you need more specific help, please post the relevant parts of your XAML and code behind.