I have a master/details relationship. Is it possible in the master to have a calculated property that corresponds to the number of details in the relationship.
Something like "select count(ID) from details where master_id=?" (I don't know if it is possible to have some parameters in the formula)

If the collection is lazy and you don't want to initialize it, then use a filter. Otherwise, just use its size()...

I want to have a getNumberOfDetails() in my master class that gives me the number of details without loading the details collection. What embarrass me with the filter is that it puts some hibernate code into my class.
I am wondering why the "size" method of the collection proxy does not use a filter in the background to avoid loading the collection when I just want the size.

Because it is easy enough to do from application code...

Ok but you are agree with me that I have to put some Hibernate code into my Master object, aren't you ?
I'am agree with you that it is easy to do in the application but it is not as 'transparent' as the 'size".

depends how you have set up your architecture. Sounds like just another argument for DAOs.

I have some "persistence-related" code in my domain objects, but because it all happens through DAO interfaces, there is nothing Hibernate specific in any of my domain entities....