The relationship could not be changed because one or more of the foreign-key properties is non-nullable

Question

I am getting this error when I GetById() on an entity and then set the collection of child entities to my new list which comes from the MVC view.

The

Answer 1

This type of solution did the trick for me:

Parent original = db.Parent.SingleOrDefault(t => t.ID == updated.ID);
db.Childs.RemoveRange(original.Childs);
updated.Childs.ToList().ForEach(c => original.Childs.Add(c));
db.Entry(original).CurrentValues.SetValues(updated);

Its important to say that this deletes all the records and insert them again. But for my case (less then 10) it´s ok.

I hope it helps.