Is there a way to automatically load navigational property using the .NET Entity Framework?

Question

Stepping away more and more from writing SQL for my applications, I decided to give the Entity Framework a try. However, I've run into something I believe is causing me to write more code than I think is strictly necessary.

When I accessed some navigational properties, I discovered that all many-to-one relations (simple references) were null and all one-to-many and many-to-many relations (EntityCollections) were empty.

For example: I have a User with a reference to a Group. When I have retieved a User, by using a simple select-by-id, the Group property is null. If I want to access the Group I have to manually load it (using User.GroupReference.Load()). So I added a GetGroup() method in User which checks whether the Group is loaded already and, if not, does so and then returns the Group.

Now this will result in a lot of highly similar methods for all navigational properties. And it all results in the navigational properties not being used, only my custom-made Get"PropertyName"() method's are now being used.

I don't want to expand my queries (linq to entities) to immediately load all these properties, because it's not always known at first what is needed. And besides, it would cause a lot of queries to have to be made.

Is there a way to configure the Entity Framework to load these objects when they happen to not be present? So when I access User.Group and the group is not loaded yet, it is loaded automatically? Or am I stuck using my own Get"PropertyName"() method's as long as I'm trying to load objects only on demand (or "just-in-time")?

Some extra info: I'm using VS2008 SP1 with .NET 3.5 SP1. The Entity Framework I'm using is the one that got shipped with it.

Answer 1

You can get EFLazyLoading - this will add transparent lazy loading support to the Entity Framework by replacing the code generator.

There is no build-in support for transparent lazy loading in the Entity Framework 1.0 - only eager loading using Include() and manual lazy loading using Load(). I am not sure about the Entity Framework 2.0 but if there is no build-in support it should at least be easier to add than before because of the use of T4 for code generation.