A guide into OR/M implementation challengesCRUD
One of the more annoying things about any DAL is dealing with the repetitive nature of talking to the data source. One of Davy’s stated goal in going this route is to totally eliminate those. CRUD functionality shouldn’t be something that you have to work with for each entity, it is just something that exists and that you get for free whenever you are using it.
I think he was very successful there, but I also want to talk about his method in doing so. Not surprisingly, Davy’s DAL is taking a lot of concepts from NHibernate, simplifying them a bit and then applying them. His approach for handling CRUD operations is reminiscent of how NHibernate itself works.
He divided the actual operations into distinct classes, called DatabaseActions, and he has things like FindAllAction, InsertAction, GetByIdAction.
This architecture gives you two major things, maintaining things is now far easier, and playing around with the action implementations is far easier. It is just a short step away from Davy’s Database Actions to NHibernate’s event & listeners approach.
This is also a nice demonstrations of the Single Responsibility Principle. It makes maintaining the software much easier than it would be otherwise.