EclipseLink doesn't update entity relations after persist

Question

Situation:
I have two entities related with a onetomany/manytoone relationship.

@Entity
public class EntityA{
  @ManyToOne()
  @JoinColumn(name="tableb_fk_id")
  private EntityB entityB;
}

@Entity
public class EntityB{
  @OneToMany(mappedBy="entityB")
  private List<EntityA> entityAList;
}

Imagine a PK called id and getter and setter being there for each class, too.

This is how i persist and read them:

public void persist(Object entity){
  entityManager.getTransaction().begin();
  entityManager.persist(entity);
  entityManager.getTransaction().commit();
}

public EntityB getEntityB(Object id){
  entityManager.getTransaction().begin();
  EntityB entity = entityManager.find(EntityB.class, id);
  entityManager.getTransaction().commit();
  return entity;
}

Now to get the persisted EntityB related to the persisted EntityA i call following:

getEntityB(entityA.getEntityB().getId());

Problem:
If i create an instance of EntityA and set a relation to an already existing instance of EntityB and persist this new instance all data are correctly saved to the database. But if i request the instance of EntityB from my EntityManager, it will not contain the just persisted instance of EntityA in its list. If i reload my persistence layer and flush it with the data from the database, it is there.

EntityA newEntityA = new EntityA();
EntityB existingEntityB = getEntityB(5); // just an example
newEntityA.setEntityB(existingEntityB);
perstist(newEntityA);
EntityB entityBforEntityA = getEntityB(newEntityA.getEntityB().getId());
entityBforEntityA.getEntityAList(); // <- does not contain newEntityA unless i restart

Question:
Why does my EclipseLink not update the newly persisted relation and how can i make it do that?

why not post your persistence code where you are doing all of these things, including transaction boundaries, and then people can comment on what you are doing — Neil Stockton
@NeilStockton sadly this is for work and i am not allowed to post the actual code. The example-entities are about as complex as my actual entities. they just have different names. I guess i can add the adjusted transation-code, too. — Basti
To refresh an object in JPA you need to call refresh() on it, or execute a Query or find() operation using the refresh query hint. Somthing like this entityManager.persist(EntityA); entityManager.refresh(EntityA); — Saulius Next
@SauliusNext it is not the persisted entity which isnt updated, it is the related entity which was persisted before the new one already. I updated my post — Basti
Check this: stackoverflow.com/questions/17870686/… also check cascade wiki.eclipse.org/EclipseLink/UserGuide/JPA/… — Saulius Next

hrs hrs · Accepted Answer · 2020-08-13T15:03:28

Stumbled upon this today. Let me welcome myself to the club.

As other answers pointed out, it's a cache problem. You can get around it without having to disable the shared cache by forcing EntityManager to fetch entity directly from database:

SomeEntityWithRelationship ent = em.find(SomeEntityWithRelationship.class, "someEntityPK", Map.of("javax.persistence.cache.retrieveMode", CacheRetrieveMode.BYPASS));

Another option is to simply use the relationship instead of directly persisting the related entity. I.e. if SomeEntityWithRelationship has a Set<RelatedEntity>, directly add to that Set<RelatedEntity> instead of manually instantiating a RelatedEntity and calling entityManager.persis(relEntity) on it.

Examples use eclipselink.

EclipseLink doesn't update entity relations after persist

1 Answers