Code First: Independent associations vs. Foreign key associations?

Question

I have a mental debate with myself every time I start working on a new project and I am designing my POCOs. I have seen many tutorials/code samples that seem to favor fo

Answer 1

Independent association doesn't work well with AddOrUpdate that is usually used in Seed method. When the reference is an existing item, it will be re-inserted.

// Existing customer.
var customer = new Customer { Id = 1, Name = "edit name" };
db.Set().AddOrUpdate(customer);

// New order.
var order = new Order { Id = 1, Customer = customer };
db.Set().AddOrUpdate(order);

The result is existing customer will be re-inserted and new (re-inserted) customer will be associated with new order.

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Unless we use the foreign key association and assign the id.

 // Existing customer.
var customer = new Customer { Id = 1, Name = "edit name" };
db.Set().AddOrUpdate(customer);

// New order.
var order = new Order { Id = 1, CustomerId = customer.Id };
db.Set().AddOrUpdate(order);

We have the expected behavior, existing customer will be associated with new order.