[FIXED] Spring with Hibernate JPA - EntityManager is closed exception

Issue

I am using EntityManagerFactory(injected) to create entityManager each time I need to access the db. I have the following code which throws,

org.springframework.dao.InvalidDataAccessApiUsageException: EntityManager is closed

entityManager = entityManagerFactory.createEntityManager();

List<Object> list = entityManager.createQuery("FROM Class").getResultList();

entityManager.close();

return list.toArray(new Object[list.size()]);

I am creating an EntityManager, querying db for some results, closing EntityManager and returning result to someone who wants those results. I think I can figure out what's wrong. The getResultList() returning objects which are managed. So, trying to access them after closing the EntityManager causing the error(Well, I think...). I tried entityManager.clear() before closing it. I got the same error. I tried detaching each object from the list(entityManager.detach(obj)), before closing it. Still, I got the same error. I tried annotating with @Transactional(readOnly=true) on the method. No use.

I am not going to modify the objects. I just need them to display on the UI. Can you give me a solution for that? I am using Spring boot + hibernate JPA + AngularJS + Postgresql.

(PS: I can't left the entityManager open. Left it open, I got connection limit exceeded error. It is not a best way either)

Solution

Why don't you inject the entity manager instead of the factory? This way you can delegate creation and disposal to the framework, gettind also rid of the connection limit error (since the framework will handle all of that for you).

You should be able to inject it this way :

@PersistenceContext
private EntityManager em;

Then you can just use it.

Answered By - francesco foresti