Question

I have an entity Venue with its Events:

  Event { ID, Name, DateTime }
  Venue { ID, Name, @OneToMany List<Event> events}

What I would like to achieve is to be able to call these functions in view (with OpenEntityManagerInView):

  customVenue.getId(); // no problem
  customVenue.getName(); // no problem
  customVenue.getEvents(); // no problem
  customVenue.getCurrentEvents(); // hm?
  customVenue.getPastEvents(); // hm?

There might be thousands of events in the database, so iterating over the “events” to get the current ones might not be a good idead.

Is this a correct approach? Is this feasible? How can I split events in current and past and to have them ordered?

Thanks!

Answer 1

Of course it’s possible. But not using a method of customVenue (unless the entity has a reference to the entity manager, which is a bad idea).

Execute a query:

String jpql = "select event from Venue venue"
              + " inner join venue.events event"
              + " where event.date < :now"
              + " order by event.date asc";
List<Event> pastEvents = em.createQuery(jpql, Event.class)
                           .setParameter("now", new Date())
                           .getResultList();