必须管理实体以调用删除

Question

What's going on here?

@Stateless
@LocalBean
public class AppointmentCommentDao {
    public void delete(long appointmentCommentId) {
        AppointmentComment ac = em.find(AppointmentComment.class, appointmentCommentId);
        if (ac != null)
        {
            em.merge(ac);
            em.remove(ac);
        }
    }
    @PersistenceContext
    private EntityManager em;
}

On the call to remove I get an IllegalArgumentException with the message being Entity must be managed to call remove: ...., try merging the detached and try the remove again.

Answer 1

In your case merge is not needed, because ac is not deattached in any point between em.find and em.remove .

In general when entity is deattached, EntityManager's method merge takes entity as argument and returns managed instance . Entity given as argument does not transform to be attached. This is explained for example here: EntityManager.merge . You have to go for:

    AppointmentComment toBeRemoved = em.merge(ac);
    em.remove(toBeRemoved);

Answer 2

Try this:

entity = getEntityManager().getReference(AppointmentComment.class, entity.getId());
getEntityManager().remove(entity);