All the examples I\'ve found refer to a class called ObjectContext, which doesn\'t appear to exist in CTP5. I must stress at this point, CTP5 is my first exposure to the Ent
When you Attach an entity, it goes to Unchanged state (it has not been changed since it attached to the context). All you need to is to explicitly change the Entity State to Modified:
_context.Users.Attach(user);
_context.Entry(user).State = System.Data.Entity.EntityState.Modified;
_context.SaveChanges();