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    This is a good idea but for smaller projects it really starts to feel like overkill. This approach also requires a translation layer between the ORM persistence layer and the domain model. Commented Mar 21, 2012 at 11:39
  • @maple_shaft agreed, and that's what I meant by "mapping" :-) Commented Mar 21, 2012 at 11:42
  • @Ozz, the way I've worked is exactly that, the entity classes ARE the domain model (and I might add with quite lots of success). I agree that it ties the domain model to the schema, but that's exactly what I want, as I use convention over configuration, and the nice side effect is that if I see a field on an entity, I don't need to think hard about the name of the table and column where that information is stored. Commented Mar 21, 2012 at 11:54
  • @Augusto I've done it too! and as maple_shaft says, it's fine for small CRUD style apps, but there are many issues as the OP is finding out. One example might be where you have a many to many mapping table eg: StudentClasses, that maps Students to their classes and just contains StudentID and classID, you would not necessarily want to map this in your domain. That's just a quick off the top of my head example. Commented Mar 21, 2012 at 12:07
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    @Ozz: Your comment seems to contradict the very idea of an ORM. An ORM doesn't "tie your domain directly to your DB schema". The ORM maps your domain to a DB schema, without the need for a separate DAO layer. That's the whole point of an ORM. And most ORMs handle many-to-many mappings just fine, with no domain model needed for the mapping table. Commented Mar 21, 2012 at 16:54