Session management of Foreign key relationship

carfield · **Joined:** Mon May 10, 2004 3:50 am **Posts:** 1

I have 2 table with foreign key constraint enabled. When I use hibernate sync. to generate the schema mapping file, it help me to add the following tag to ensure a list in parent table to access child record:

Quote:

However, then in my code I load an instance of parent object, then save it. When I saving the object, it complaint about : "Illegal attempt to associate a collection with two open sessions"

The java code of load is:

Quote:

session = getInstance().openSession(con);
session.load(st, st.getId()); // st is parent
TOP.read(session); // child record
LEFT.read(session);
BUTTON.read(session);
session.flush();
session.disconnect();

The java code of save is:

Quote:

session = getInstance().openSession(con);
session.update(st);
TOP.save(session);
LEFT.save(session);
BUTTON.save(session);
session.flush();
session.disconnect();

I think the exception is cause by I am not suppose to save / load the child record outside hibernate if I have put the above tag, right? I guess it should have better exception message about this, rather than "Illegal attempt to associate a collection with two open sessions", right?[/quote]

christian · **Posted:** Tue Jul 13, 2004 7:38 am

It looks like your code is leaking Sessions, it certainly doesn't look correct. You should reconnect(), not open a new Session, if you disconnect(). Don't forget to close() it at some point. This is more advanced than you might realize, don't use disconnect()/reconnect() unless you are implementing long running Application Transactions with a single Session. See Hibernate in Action for more info.

anthony · **Posted:** Tue Jul 13, 2004 7:53 am

your code is also leaking transaction...