[FIXED] SqlExceptionHelper thrown when inserting linked entities in a Postgresql db with Hibernate and JPA

Issue

So, I have 2 entities defined in my code, like this:

public class EntityA {

    @ManyToOne(cascade = ALL, fetch = LAZY, optional = false)
    @JoinColumn(name = "entity_b_id", nullable = false)
    private EntityA entityA;

}

public class EntityB {

    @Id
    @SequenceGenerator(name = "seq_entity_b", sequenceName = "seq_entity_b", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq_entity_b")
    @Column(name = "id", unique = true, nullable = false)
    private Long id;

    [...other stuff...]

    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "seq_entity_b_external_id")
    @SequenceGenerator(name = "seq_entity_b_external_id", sequenceName = "seq_entity_b_external_id", allocationSize = 1)
    @Column(name = "external_id", nullable = false, unique = true)
    private Long externalId;
}

Then I have a dao layer defined like this:

@Repository
public class EntityADao {

    @PersistenceContext
    private EntityManager entityManager;

    public void save(EntityA entityA) {
        entityManager.persist(entityA);
        entityManager.flush();
    }
}

When this code is triggered, I get this exception thrown though:

2021-02-18 13:40:21.434 ERROR 17530 --- [tp1239821079-39] o.h.engine.jdbc.spi.SqlExceptionHelper   : ERROR: null value in column "external_id" of relation "entity_b" violates not-null constraint
Detail: Failing row contains (111111, aaaaaaaa, Aaaaaa, 111111, AAAAAA, 1, VALUE, null).
org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [external_id" of relation "entity_b]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement

Notice how the last value is null, that one should be the external_id. When I turn on the sql logs for jpa, I do not see anywhere the seq_entity_b_external_id called (I expected something like select next_val('seq_entity_b_external_id'). Can anyone help me solve this issue? Thanks in advance.

Solution

Thanks to @Christian Beikov answer, I got an hint. The error I did was to use multiple sequences on an entity, which is something you cannot do. I solved the issue following the solution in this post

Answered By - eager_to_learn
Answer Checked By - Gilberto Lyons (JavaFixing Admin)