Different behavior between Spring Boot 3.0.5 & 2.7.10, when using @EntityGraph with @ElementCollection/@CollectionTable

[Eng-Fouad]

I have this field inside UserEntity:

@ElementCollection(fetch = FetchType.LAZY)
@CollectionTable(name = "users_roles_mapping", joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"))
@Enumerated(EnumType.ORDINAL)
@Column(name = "role_id")
Set<Role> roles;

and I have this method inside UsersRepository:

@EntityGraph(attributePaths = {"roles"})
Optional<User> queryFirstById(int id);

On Spring Boot v3.0.5, user.getRoles() always contain single role despite the user has multiple roles. On Spring Boot v2.7.10, user.getRoles() works as expected and it contains all assigned roles.

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Here is a reproducer: https://github.com/Eng-Fouad/spring-entity-graph-bug

[schauder]

This sounds very much like a Hibernate issue, since all the JPA mapping is done by it.
I recommend creating a reproducer based purely on Hibernate and submitting an issue with them.

If you think this is actually a Spring Data issue, please provide a reproducer for the issue including a test case that demonstrates the correct behaviour using the EntityManager and the Criteria API directly.

[Eng-Fouad]

@schauder What Hibernate versions that Spring Boot 3.0.5 & 2.7.10 use?

Also, I don't know how to use Hibernate API that corresponds to @EntityGraph spring annotation.

[schauder]

3.0.5 uses Hibernate 6.1.7
2.7.10 uses Hibernate 5.6.15.Final

See: https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-data-jpa/2.7.10

For how to use a fetch graph there is a decent description at
https://www.baeldung.com/jpa-entity-graph

The hint names are defined in Hibernates QueryHints. Using them avoids errors due to the javax -> jakarta change
https://docs.jboss.org/hibernate/orm/5.1/javadocs/org/hibernate/jpa/QueryHints.html

[Eng-Fouad]

I couldn't figure out how to replicate the issue using JPA API only.

Using Spring Boot 3.0.5, and given:

@Repository
public interface UsersRepository extends JpaRepository<UserEntity, Integer> {
	@EntityGraph(attributePaths = {"roles"})
	UserEntity queryFirstById(int id);
}

@RequiredArgsConstructor
@Slf4j
@Service
public class UsersService {

	private final UsersRepository usersRepository;

	@PersistenceContext
	private EntityManager entityManager;

	@Transactional(isolation = Isolation.READ_COMMITTED, readOnly = true)
	public Set<Role> getUserRolesByIdV1(int id) {
		return usersRepository.queryFirstById(id).getRoles();
	}

	@Transactional(isolation = Isolation.READ_COMMITTED, readOnly = true)
	public Set<Role> getUserRolesByIdV2(int id) {
		var cb = entityManager.getCriteriaBuilder();
		var criteriaQuery = cb.createQuery(UserEntity.class);
		Root<UserEntity> root = criteriaQuery.from(UserEntity.class);
		criteriaQuery.where(cb.equal(root.<Integer>get("id"), id));
		TypedQuery<UserEntity> typedQuery = entityManager.createQuery(criteriaQuery);

		EntityGraph<UserEntity> entityGraph = entityManager.createEntityGraph(UserEntity.class);
		entityGraph.addAttributeNodes("roles");
		typedQuery.setHint(EntityGraphType.FETCH.getKey(), entityGraph);

		UserEntity userEntity = typedQuery.getSingleResult();
		return userEntity.getRoles();
	}
}

getUserRolesByIdV2 returns 2 items while getUserRolesByIdV1 returns 1 item.

How to make getUserRolesByIdV2 do the exact same thing as getUserRolesByIdV1? I need your help.

[Eng-Fouad]

I was able to replicate the bug using JPA API:

EntityGraph<UserEntity> entityGraph = entityManager.createEntityGraph(UserEntity.class);
entityGraph.addAttributeNodes("roles");

Query query = entityManager.createQuery("SELECT u FROM UserEntity u WHERE u.id = 1");
query.setMaxResults(1);
query.setHint(EntityGraphType.FETCH.getKey(), entityGraph);

UserEntity userEntity = (UserEntity) query.getSingleResult();
return userEntity.getRoles();

This returns 2 roles in 2.7.10 and 1 role in 3.0.5.

[Eng-Fouad]

Submitted a bug report to Hibernate team: https://hibernate.atlassian.net/browse/HHH-16408

[schauder]

Thanks for the confirmation.

[Eng-Fouad]

This bug should be fixed in Hibernate 6.2.0: https://hibernate.atlassian.net/jira/software/c/projects/HHH/issues/HHH-15964