JPA2 Criteria-API: select… in (select from where)

Question

I have the following database model:

A
aId

AB
aId
bId

B
bId
status

In a Spring data Specification, I want to return the instances of A wh

Answer 1

The Specification that returns instances of A using Criteria API is the following:

public class ASpecifications {
     public static Specification test(final String status) {
          return new Specification() {
          @Override
          public Predicate toPredicate(Root a, CriteriaQuery query, CriteriaBuilder cb) {
            Subquery sq = query.subquery(A.class);
            Root ab = sq.from(AB.class);
            sq.select(ab.get(AB_.id).get(ABPK_.a));
            sq.where(cb.equal(ab.get(AB_.id).get(ABPK_.b).get(B_.status), status));

            Predicate p = cb.in(a).value(sq);
            return cb.and(p);
          }
        };
     }
}