Using Include in Entity Framework 4 with lambda expressions

The RTM version of Entity Framework 4.1 actually includes extension methods in the EntityFramework.dll file, for eager loading with lambda through the Include function. Just include the DLL in your project and you should be able to write code like:

var princesses1 = context.Princesses.Include(p => p.Unicorns).ToList();

Remember to add an Import/Using statement to include the System.Data.Entity namespace. Otherwise the compiler cannot find the extension methods. E.g:

using System.Data.Entity;

See this ADO.NET team blog article for more information.

No there is no official support for Include with lambda expression in RTM at the moment. I'm using this.

When we are talking about CTP4 we are meaning Entity Framework Feature. It is newer API than EF4. It mainly includes Code First and few other improvements.

Although this is implied in the question, for anyone else who has the same problem where they can't use lambdas with .Include, make sure you have this:

using System.Data.Entity;