Hello all,

I am using Hibernate 3.0.

I have two classes: Technology_Type, Technology associated with each other in a one-to-many relation.

Mapping for Technology_Type is below:



When I get the technologies beloning to a technology type everything is fine. But when I close the session (as shown in red), I get "...failed to lazily initialize a collection of role..."


// find the technologies under type say - 4
Technology_Type tt = (Technology_Type)ses.load(Technology_Type.class, new Long(4));

Set technologies = tt.getTechnologies();
Long tt_id = tt.getId();
String name = tt.getName();

ses.close();
System.out.println("There are "+technologies.size()+ " that belong to "+name +":");

When I have read all the properties of Technology_Type, I guess I should be able to close the session.

By placing the ses.close() after the System.out.println.... everything works fine.

Why?

J2EE_PRO
--------------------------
I think, therefore I survive

If you really want to have your Set loaded right away you should be using lazy="false" in your <set> tag. Otherwise, you're telling Hibernate to wait until you need the data, then you close the session, and then you ask for the data. It can't go fetch the data if there's no session open.

Lazy loaded objects in reality are Hibernate proxies. Once you call session close you will have resources associated with it released. It means data behind proxies not accessible anymore. In your example collection of Technologies was not initialized yet. You got reference on proxy collection instead.