What's all the hype over objectsets in Entity Framework 4?

Question

I am an intermediate user of EF in .net 3.5 and have recently moved to working with .net 4.

One thing i keep coming across when reading various tutorials is the use of ObjectSets instead of ObjectQuerys and that they are a great new feature.

What is so great about them?

Please enlighten me.

Kind regards, Kohan

Answer 1

Not sure if that's what you mean in your question, but what's really cool about ObjectSet is that it implements an interface IObjectSet which means you can fake it very easily and test the code down until the data access layer.

What's even cooler, is that since the ObjectSet use generic types (IObjectSet< T >), you can have a generic repository and implement the Unit Of Work pattern.

public interface IRepository<T> where T : class
{
     IQueryable<T> GetQuery();
     IEnumerable<T> GetAll();
     IEnumerable<T> Find(Func<T, bool> where);
     T Single(Func<T, bool> where);
     T First(Func<T, bool> where);

     void Delete(T entity);
     void Add(T entity);
     void Attach(T entity);
     void SaveChanges();
}

complete article here :

http://elegantcode.com/2009/12/15/entity-framework-ef4-generic-repository-and-unit-of-work-prototype/