Hello.

I'm building ASP.NET MVC2 application, and using Entity Framework as ORM. I am having troubles updating object in the database. Every time I try entity.SaveChanges(), EF inserts new line in the table, regardless of do I want update, or insert to be done. I tried attaching (like in this next example) object to entity, but then I got

{"An object with a null EntityKey value cannot be attached to an object context."}

Here's my simple function for inserts and updates (it's not really about vehicles, but it's simpler to explain like this, although I don't think that this effects answers at all)...

        public static void InsertOrUpdateCar(this Vehicles entity, Cars car)
    {
        if (car.Id == 0 || car.Id == null)
        {
            entity.Cars.AddObject(car);
        }
        else
        {
            entity.Attach(car);
        }
        entitet.SaveChanges();
    }

I even tried using AttachTo("Cars", car), but I got the same exception.

Anyone has experience with this?