How do I change this Hibernate code with org.hibernate.criterion.Restrictions code to JPA. Is there any alternatives to Restrictions API?

Question

Does anyone know how to change this to JPA? and if there are any alternatives for the org.hibernate.criterion.Restrictions API? Thank you!

public void initShowAFilterCriteria (Criteria crit, ShowingAFilter filter, Object user) {

    if(filter == null) {
        return; // do nothing
    }
    switch (filter) {
        case ALL;
            break; // do nothing
        case MINE;
            crit.add(Restrictions.or(Restrictions.isNull("something"),
                    Restrictions.eq("something.id", user.getId())));
            crit.add(Restrictions.eq(Object.A_CONSTANT, "N"));
            break;
            /**
             * the rest of the switch statments are in a similar construct
             */
            
    }

}

score 0 · Answer 1 · answered Jul 03 '21 at 05:33

You can use CriteriaBuilder and CriteriaQuery interface instead of Hibernate's Restrictions and Criteria, just like follows:

public CriteriaQuery<User> initShowAFilterCriteria (CriteriaBuilder cb, ShowingAFilter filter, Object user) {

    CriteriaQuery<User> cq = cb.createQuery(User.class);
    Root<User> root = cq.from(User.class);

    if(filter == null) {
        return; // do nothing
    }
    switch (filter) {
        case ALL;
            break; // do nothing
        case MINE;
            cq.select(root)
                .where(cb.or(
                    cb.isNotNull(root.get("something")), 
                    cb.equal(root.get("something.id"), user.getId())))
                .where(cb.equal(root.get(Object.A_CONSTANT), "N"));
            break;
            /**
             * the rest of the switch statments are in a similar construct
             */
    }
    return cq;
}

Attention: Unlike Hibernate’s Criteria can perform a query directly, using JPA's API, you need return a CriteriaQuery instance to do that.

Thank you Desmond, but what if I already declared those variables outside the method initShowingFilterCriteria() and this method just built on it. For example: — Yaw_Osei, Jul 07 '21 at 14:28
I mean't what if this line of code had already been declared outside the method: CriteriaQuery cq = cb.createQuery(User.class); Root root = cq.from(User.class); — Yaw_Osei, Jul 08 '21 at 14:00
You just need to pass those variables(`cb`, `cq`, `root`) as arguments of the method initShowingFilterCriteria. — Desmond Stonie, Jul 09 '21 at 01:16

How do I change this Hibernate code with org.hibernate.criterion.Restrictions code to JPA. Is there any alternatives to Restrictions API?

1 Answers1