I'm trying to build a Criteria query, but I'm having some difficulty.

In my system, a patient Case contains a Diagnostic, and each Diagnostic contains one or more MaladyDiagnostic. A MaladyDiagnostic can be any of several subclasses (let's call them MaladyDiagnosticA, MaladyDiagnosticB, and MaladyDiagnosticC, all of which extend MaladyDiagnostic).

The gist of my query is that I want to find all Cases that have a MaladyDiagnosticA in their Diagnostic's collection of MaladyDiagnostics.

Here's my (failed) attempt:



In addition to probably being horribly inefficient, the above doesn't work. I always get zero rows returned, even though there are Cases in the test system that have a Diagnostic that contains a MaladyDiagnosisA. I'm quite new to Hibernate's Criteria API, and simply haven't been able to coax it to work. Any help would be greatly appreciated!

Projections.id() return a IdentifierProjection instance and I think you need a list of your identifier type. Why don't you try with subQuery.setProjection(Projections.property("<id_property>")); Then you need catch them into a list, not into a query. And you can have problems if the list is empty.

I hope you have lucky, and so sorry for my english level ;)

Embarrassingly enough, it turns out my test data wasn't correct after all, so all my queries were returning 0 results. Fixing my test data solved my problems. Sorry for using up your time!