如何获取带有 bytea 类型 id 列的表？

Question

I have a PostgreSQL database and I want to fetch some data with Hibernate. I got an entity like;

@Entity
public class User {

    @Id
    @Type(type = "uuid-binary")
    @GenericGenerator(name = "user-generator", strategy = "uuid2")
    @GeneratedValue(generator = "user-generator")
    @Column(name = "user_id", length = 16, unique = true, nullable = false)
    private UUID userId;


    ....

}

When I try to get all User values with Hibernate there is no problem. Hibernate maps UUID fields. But when I try to get a specific User with UUID it returns empty result. How can I fetch a single User with userId value?

List<User> users = userDao.getAll();  //I can get all users with non-empty userId fields
userDao.getWithId(users.get(0).getUserId())  // returns null.

users.get(0).getUserId()  //returns java.util.UUID instance like "33333-3333..."

EDIT:

public User getWithId(UUID Id) {
    EntityManager em = emFactory.createEntityManager();
    try {
        CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
        CriteriaQuery<User> criteriaQuery = criteriaBuilder.createQuery(User.class);
        Root<User> typeRoot = criteriaQuery.from(User.class);
        criteriaQuery.select(typeRoot).where(criteriaBuilder.equal(typeRoot.get("userId"), Id));
        final Query query = em.createQuery(criteriaQuery);
        return (User) JPAHelpers.getSingleResultOrNull(query);
    } catch (Exception e) {
        throw e;
    } finally {
        em.close();
    }
}

Answer 1

Although, you didn't share the implementation of getWithId() method. I am assuming that you're using the JPA Repository methods. Try annotating the UUID field with:

@Type(type="org.hibernate.type.UUIDBinaryType")

or

@Type(type="org.hibernate.type.UUIDCharType") // if column is VARCHAR

Or try defining the columnDefinition parameter in @Column annotation:

@Column(name = "user_id", columnDefinition = "BINARY(16)", unique = true, nullable = false)