Query with using CriteriaQuery and EntityManager(Hibernate)

Question

How create query with using CriteriaQuery and EntityManager for this SQL query:

SELECT * FROM user WHERE user.login = '?' and user.password = '?' 

I try so:

        final CriteriaBuilder criteriaBuilder = getEntityManager().getCriteriaBuilder();
        final CriteriaQuery<User> criteriaQuery = criteriaBuilder.createQuery(User.class);
        Root<User> root = criteriaQuery.from(User.class);
        criteriaQuery.select(root);
        criteriaQuery.where(criteriaBuilder.gt(root.get("login"), userLogin));
        return getEntityManager().createQuery(criteriaQuery).getResultList().get(0);

Answer 1

Your code looks like it's on the right track, except that it only has one WHERE condition, which does not agree with your raw SQL query, which has two conditions.

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<User> q = cb.createQuery(User.class);
Root<User> c = q.from(User.class);
q.select(c);
ParameterExpression<String> p1 = cb.parameter(String.class);
ParameterExpression<String> p2 = cb.parameter(String.class);
q.where(
    cb.equal(c.get("login"), p1),
    cb.equal(c.get("password"), p2)
);
return em.createQuery(q).getResultList().get(0);

As a side note, in real life you would typically not be storing raw user passwords in your database. Rather, you be storing a salted and encrypted password. So hopefully your actual program is not storing raw passwords.