Help writing test case for lazy loading

Hibernate ORM
1

I’m attempting to use hibernate-test-case-templates to ask a question about lazy loading behavior for entities. In the real application I have a Parent / Child entity relationship. I think I should be able to call child.parent.getId() and hibernate will not load the parent because that id is present as a foreign key on the child.

I’m getting a third behavior from this test case which is neither what I’m seeing in my app, nor what I expect to see.

@Test
void hhh123Test() throws Exception {
  EntityManager entityManager = entityManagerFactory.createEntityManager();
  entityManager.getTransaction().begin();

   Parent parent = new Parent();
   entityManager.persist(parent);

   Child child = new Child().setParent(parent);
   entityManager.persist(child);

   entityManager.getTransaction().commit();
   entityManager.close();

   // LOAD ------------------------------------------------------------------
   EntityManager entityManager2 = entityManagerFactory.createEntityManager();
   entityManager2.getTransaction().begin();

   Child loaded = entityManager2.find(Child.class, child.getId());

   System.out.println();

   Parent loadedParent = loaded.parent;
   long a = loadedParent.getId();

   entityManager2.getTransaction().commit();

   entityManager2.close();
 }

In the test case, when I load the Child entity, it also loads the parent before loaded.parent is accessed:

Hibernate: 
    select
        c1_0.id,
        c1_0.parent_id,
        c1_0.tenant_id 
    from
        Child c1_0 
    where
        c1_0.id=? 
        and c1_0.tenant_id = ?
Hibernate: 
    select
        p1_0.id,
        p1_0.tenant_id 
    from
        Parent p1_0 
    where
        p1_0.id=? 
        and p1_0.tenant_id = ?

Any ideas what’s going on here? Once I have this working as expected, I want to demonstrate that hibernate is loading the full Parent row to get the id when as far as I can tell from the documentation, it should not have to do that. Thanks!

2

There are various JPA compliance settings that are probably active when coding a JPAUnitTestCase that might affect the behavior. See JpaComplianceSettings. Most likely, it is the hibernate.jpa.compliance.proxy setting which affects your scenario.