Is Repository pattern an overkill

Question

I have been using Repository pattern (DDD and POEAA) for some time. However some of our team members have argued that it is just an extra layer of abstraction and unnecessary. I can seen some benefit in their arguments. Modern ORM solutions (NHibernate or EF) have almost everything you need. I searched and found some article like this and counterargument on this topic. So Is repository pattern an overkill?

Answer 1

It depends, mostly on the complexity of your problem and the role your Domain Model plays in the solution. For simple solutions, Repository is probably overkill. But for complex domains with a robust language and evolving needs/requirements, the Repository is a nice, clean abstraction that owns the domain object lifecycle. Many ORMs will do much of this, but, in a complex domain, there will always be some domain activity that makes sense in a repository and which is not supported by an ORM out of the box.

Bottom line: it depends on the context.

Answer 2

Mocking data access in unit tests is the main reason I use repository interfaces. Another reason maintainability - you can easily implement caching strategies, or switch to other data access implementation, like getting data from the service instead of DB.