Question

I’m learning jpa-hibernate basics.

I have this query for getting all users:

CriteriaBuilder cb = getEntityManager().getCriteriaBuilder();
        CriteriaQuery cq = cb.createQuery();
        cq.select(cq.from(Utente.class));
        return getEntityManager().createQuery(cq).getResultList();

Now I want to filter by a boolean field named ‘ghost’ where it equals true (or false, it depends).

Translated:

SELECT * FROM users WHERE ghost = 0;

Do I have to use cq.where() ? How?

Answer 1

Yes, you have to use cq.where().

Try something like this:

Root<Utente> utente = cq.from(Utente.class);
boolean myCondition = true;    // or false
Predicate predicate = cb.equal(utente.get(Utente_.ghost), myCondition);
cq.where(predicate);

Where I have used the canonical metamodel class Utente_ that should be generated automatically. This avoids the risk of making errors in typing field names, and enhances type safety. Otherwise you can use

Predicate predicate = cb.equal(utente.get("ghost"), myCondition);