How do you wrap a circular reference operation in a single transaction using Entity Framework 4?

Question

I have a table of Persons and a table of Things, where each Thing is owned by a Person and each Person has a FavoriteThing.

Persons
   PersonID int <PK>
   FavoriteThingID int <FK>

Things
   ThingID int <PK>
   PersonID int <FK>

I would like to be able to add a Person and his/her favorite Thing, as well as setting that Thing's PersonID to the new Person, in a single transaction, without having DTC promote the transaction to distributed. Wrapping the operation in a TransactionScope() and manually managing the Entity connection does not appear to work:

        ThingEntities ent = new ThingEntities();

        using (TransactionScope scope = new TransactionScope())
        {
            ent.Connection.Open();

            Thing t = ent.CreateObject<Thing>();

            ent.Things.AddObject(t);

            ent.SaveChanges(false);

            Person p = ent.CreateObject<Person>();
            t.Person = p;
            ent.Persons.AddObject(p); 
            p.FavoriteThing = t;

            ent.SaveChanges(false);

            scope.Complete();

            ent.AcceptAllChanges();
            ent.Connection.Close();
        }

This results in a "Unable to determine a valid ordering for dependent operations." exception on the second SaveChanges() call.

Is there a simple way to do this?

Thanks

Answer 1

You don't need TransactionScope for this. You can do it in one call to SaveChanges, which means one transaction.

Person p = ent.CreateObject<Person>();
p.FavoriteThing = ent.CreateObject<Thing>();
ent.Persons.AddObject(p); 
ent.SaveChanges();