Question

If I have an entity that has an association (e.g. Book.Publisher), how do I save a new Book and associate it with an existing Publisher?

BTW I don’t want to expose FK associations (i.e. PublisherId) in my model.

I had been using something like this:

var book = new Book { Title="whatever", Publisher = new Publisher { Id = 42 } };
context.Books.Add(book);

But this just tries to add a new publisher.

I saw this question which suggested using ObjectStateManager.ChangeObjectState but I get an error if I try this – The ObjectStateManager does not contain an ObjectStateEntry with a reference to an object of type ‘Blah.Publisher’.

Answer 1

var pub = new Publisher { Id = 42 };
context.Publishers.Attach(pub);
var book = new Book { Title="whatever", Publisher = pub };
context.Books.Add(book);