Hibernate criteria query on different properties of different objects

Question

Suppose I have classes like:

class A {
 B getB();
 C getC();
}

class B {
 String getFoo();
}

class C {
 int getBar();
}

and I want to filter criteria on A, two filters on different subclass properties, like:

Criteria criteriaA = session.createCriteria(A.class);
Criteria criteriaB = criteriaA.createCriteria("b").add(Restrictions.eq("foo", "Something"));
Criteria criteriaC = criteriaA.createCriteria("c").add(Restrictions.eq("bar", 0));

What I want to do is combine criteriaB and criteriaC using an "or" clause, something like:

//this does not work
criteriaA.add(Restrictions.disjunction().add(criteriaB).add(criteriaC));

How can I accomplish this? I am stumbling a little over the API here.

Answer 1

Use aliases instead of nested criteria:

Criteria criteria = session.createCriteria(A.class)
 .createAlias("b", "b_alias")
 .createAlias("c", "c_alias")
 .add(Restrictions.disjunction()
  .add(Restrictions.eq("b_alias.foo", "Something"))
  .add(Restrictions.eq("c_alias.bar", "0"))
 );