Odtnhj

Guys I get that if you load an object, close a session in hibernate and then try to get information about related objects, while the FetchType of this association is LAZY it will obviously give you LazyInitializationException. Could someone tell me why if I start another transaction and then try to load related objects I will still get this exception? Lets say I have Instructor class and one to many related Course class. Courses are lazy loaded.

Session session = sessionFactory.getCurrentSession();
session.beginTransaction();
Instructor instructor= session.get(Instructor.class, id);
session.getTransaction().commit();

session = sessionFactory.getCurrentSession();
session.beginTransaction();
System.out.println(instructor.getCourses());

session.getTransaction().commit();

why do I still get LazyInitializationException?

The key issue that is that data loaded in one transaction may contradict data loaded in an earlier transaction, since another transaction may have modified the data in the meantime.

That is, each transaction will (or strive to, in the case of weaker isolation levels) give you a consistent view of the state of the database - but combining views taken at different times can result in an inconsistent view of your data, which can cause logic errors.

That said, it is possible to extend lazy loading across transactions by using an "extended persistence context" - but that feature is rarely used in my experience.