Entity A has ManyToMany relationship with Entity B. Class B is the base class for a class hierarchy, and C is a subclass of B in the class hierarchy.


class A {

List<B> getBList();

}


Query:
get all A(s) that have a instance of C.

Note that: C is a subclass of B. It is OO. If A has an instances of any subclass of C, then the A will be included in result set.

The following code will not work using class, which is exactly match, not OO idea.

List results = session.createCriteria(A.class)
.createCriteria("bList")
.add( Restrictions.eq("class", "B") )
.list();


any help are appreciated. Thanks!

Dave

I am looking for something like:

Restrictions.instanceof(object, class);

Hibernate is OO to relational database. I expect it to have this feature. Is it possible with Hibernate? Thanks!

It's definitely possible with HQL (the .class member is provided for this purpose). If there's no equivalent in Criteria (and I couldn't find one) you could explicitly map the discriminator using a function (rather than a column: the column is already in use in your mapping) and add a Criterion for that.

Thanks!

The .class member in HQL is not OO polymorphic. It requires "Exact" match(simply String comparison)and does not consider inheritance.

I am not quite understanding the mapping function you mentioned. If you can give me an example how to use it with Criteria, it would be a great help.

In my case I am using JOINED mapping strategy, not Single-Table, so there is no discriminator column.

Your help is appreciated.

Thanks.