Weird behavour when using bidirectional oneToMany in combination with jpa postload

[JaimePolidura]

Hello,

I',m unsure if this is project is the correct place to report the following behavour I've observed, please let me know if I should report it to another github project.

With the latest spring boot 3.4.x version, I have observed the following problem in my springboot project that uses spring data jpa to persist againsts postgres database. I have created a small springboot project to reproduce this bug github project

• I have a parent entity with a oneToMany relationship to a child entity.
• In the child entity I have a bidirectional manyToOne relationship to the parent.
• Aditionally in the parent I have a jpa @PostLoad annotation where I just sort the list of children by an integer field.
• I have added a spring boot test to persist a parent whith three children, and then load all children from database.
• For your convenience, the pom.xml includes docker-maven-plugin to start postgres via docker, please use the following command: mvn docker:start -Pdocker

The test throws an exception because of during the postload in the list of children the first child's fields are null, interestingly other children have fields with values as expected, please see screenshot:

I have added a feature branch in my project revert-to-old-springboot where I use spring boot 3.3.x instead and the test is successful and the bug does not appear.

[mp911de]

Have you verified the behavior is different when using Hibernate through EntityManager?

[JaimePolidura]

I have tried to use EntityManager and the bug still appears. Here is the code that I have used:

@SpringBootTest
class HibernatePostloadBugExperimentApplicationTests {
  @Autowired
  private EntityManager entityManager;

  @BeforeEach
  @Transactional
  public void setup() {
    entityManager.createQuery("DELETE FROM Parent").executeUpdate();
    entityManager.createQuery("DELETE FROM Child").executeUpdate();
  }

  @Test
  @Transactional
  void contextLoads() {
    Parent parent = new Parent();
    entityManager.persist(parent);

    entityManager.persist(new Child(1, parent));
    entityManager.persist(new Child(2, parent));
    entityManager.persist(new Child(3, parent));

    entityManager.flush();
    entityManager.clear();

    List<Child> children = entityManager.createQuery("SELECT c FROM Child c").getResultList();
    assertEquals(3, children.size());
  }
}

Link to the code

Let me know if that is what you meant.
Thanks!

[mp911de]

Yes, that's what I was looking for. Please note that your code is slightly different (posting the reproducer from your GitHub repo):

  @Test
  void contextLoads() {
    Parent parent = new Parent();
    parentRepository.save(parent);
    childRepository.save(new Child(1, parent));
    childRepository.save(new Child(2, parent));
    childRepository.save(new Child(3, parent));

    List<Child> children = childRepository.findAll();

    assertEquals(3, children.size());
  }

All save run in their own transaction while the code ab uses a single surrounding @Transactional. To make the code truly comparable, each entityManager.persist(…) would either need to be ran in TransactionTemplate.execute(…) or your contextLoads test method must be @Transactional.

[JaimePolidura]

Oops, you are right, sorry. I have updated it, and the bug still appears.

Here is the code:

@SpringBootTest
class HibernatePostloadBugExperimentApplicationTests {
  @Autowired
  private TransactionTemplate transactions;
  @Autowired
  private EntityManager entityManager;

  @BeforeEach
  public void setup() {
    transactions.executeWithoutResult(s -> {
      entityManager.createQuery("DELETE FROM Child").executeUpdate();
      entityManager.createQuery("DELETE FROM Parent").executeUpdate();
    });
  }

  @Test
  void contextLoads() {
    Parent parent = new Parent();
    transactions.executeWithoutResult(s -> entityManager.persist(parent));
    
    transactions.executeWithoutResult(s -> entityManager.persist(new Child(1, parent)));
    transactions.executeWithoutResult(s -> entityManager.persist(new Child(2, parent)));
    transactions.executeWithoutResult(s -> entityManager.persist(new Child(3, parent)));

    List<Child> children = transactions.execute(t ->
        entityManager.createQuery("SELECT c FROM Child c").getResultList());

    assertEquals(3, children.size());
  }
}

[mp911de]

Alright. This is pretty much a confirmation about Hibernate/JPA behavior. If you consider this a bug, please file a ticket with the Hibernate issue tracker. Feel free to leave a ticket reference here.