entity framework 4 - EF4 Independent Associations - Why avoid them?

Question

I saw this comment on MSDN (link and link):

"Note that Independent Associations should often be avoided since things like N-Tier and concurrency becomes more difficult."

I'm new to EF4 and I'm building an n-Tier web app. This sounds like an important pitfall. Can someone explain to me what this means?

Answer 1

I think it's personal preference. Originally, EF was created to only use indep. associations and aligned with a more classic ERM approach. However, most of us devs are so dependent on FKs that it made life very complex. So MS gave us FKs in EF4 which meant not only having the FK as a property in the dependent entity but the relationships are defined through constraints in the conceptual model rather than buried in the mappings. There are still a few relationships that you can only define with an indep association: many to many and unique foreign keys. Note that if you are planning to use RIA Services (doesn't sound like it) that RIA only recognizes FK associations.

So if you prefer to leverage the independent associations you still absolutely can use them in EF4. They are totally supported. But as James suggests, there are a few more traps to be aware of...things that you'll need to do more explicitly because of the way EF works with graphs especially. Or that case where you do just want that FK , e.g., you have the ID of a customer but you don't h ave the instance. You could create an order but without that nice CustomerID FK property, you have to do some extra juggling to get that CustomerID in there.

hth