JPA Criteria API Fetch Entities that have a specific Parent Property Value

Question

I have a User and UserRole model, that looks like this:

User.java

public class User {

    @Id
    private Long id;

    private String name;

    @ManyToOne
    @JoinColumn(name = "ROLE_ID")
    private UserRole role;

    //All other properties...

}

UserRole.java

public class UserRole {

    @Id
    private Long id;

    private String name;

    //All other properties...

}

I need to be able to fetch all users that have role = 1L .

I'm able to do this with JPQL, as follows:

TypedQuery<SystemUser> query = entityManager.createQuery("Select u from User u left join u.role r where r.id=?1", User.class);
query.setParameter(1, roleId);
return query.getResultList();

However, for some reason, I would like to know if I can achieve the exact same thing Without JPQL , by simply using the JPA Criteria API.

Can anyone help me out?

Thanks, Sriram Sridharan

Answer 1

Try below code,

CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<User> criteriaQuery = builder.createQuery(User.class);
Root<User> root = criteriaQuery.from(User.class);
criteriaQuery.where(builder.equal(root.get("role").get("id"), roleId));
return entityManager.createQuery(criteriaQuery)..getResultList();