I suppose this is due to the fact that a projection onto a mapped entity is not allowed. However, a projection onto an data transfer object( DTO ) is allowed. Calling Include
should include properties onto the type Person which probably results in a poco object creation, while the provider will work with the Person objects.
That said, entirely new objects are used(not the ones used in your entity framework). If my assumption is correct, you can use our LocalDataSourceProvider and apply ToList() at the end of your query. That's the only way to get it work with the new objects. In case you want to use QueryableDataProvider, you will have to pass the same object types as the ones from your Entity Framework.
Hope this helps.
Telerik by Progress
Do you need help with upgrading your WPF project? Try the Telerik API Analyzer
and share your thoughts!