Entity Framework / EF4: Multiple inserts of related entities in a transactionscope

Question

I have a similar problem.

I want to make two inserts in the same transactionscope. The objects are related and have a FK relationship between them, but for several reasons I do not want to connect them via the navigation property, but only by ID.

This is a simplification of what I what I want to accomplish:

Order o = new Order();
OrderDetails d = new OrderDetails();
new Repository().SaveNew(o, d);

class Repository{

void SaveNew(Order o, OrderDetails d){
  using (TransactionScope transaction = new TransactionScope())
  {
   _context.Connection.Open();

   // order
   _context.Orders.ApplyChanges(o);
   _context.SaveChanges();

    // details
    d.OrderID = o.ID;
    _context.OrderDetails.ApplyChanges(d);
    _context.SaveChanges(); <--- UpdateException

    _context.Connection.Close();
    transaction.Complete();
  }
 }
}

The problem is that I get an UpdateException because the FK evaluation fails. I tried to remove the FK relationship and running the exact same piece of code, and it worked fine, and both objects had the right properties set. So why does this approach fail? And how should this instead be done? Again, I do not want to attach the entites via their navigation properties.

Thank you!

Answer 1

I would leave the FK relationship in the database, but delete the AssociationSet and Association from the SSDL. The designer won't let you do this, you have to edit the XML manually.

I am using EF 4 btw.

Then use AddObject and SaveChanges in your SaveNew method to add the first (parent) object. Set the foreign key Property on the child and add it with AddObject and SaveChanges.

Answer 2

I do not have development environment running to test this, but what I think is happening is:

Assuming that the id is generated in the database. At the point when you save the order you do not know the ID.

Then the order ID of the order detail is set to the ID of the order, but the order was not reloaded from the database. I suspect that the value is 0.

When you try to save the order detail with FK of 0, you get an error.

Either save both at the same time so that EF does the work for you, or reload the order.