joined-subclass and getting sub-class

zdila · **Posted:** Tue Jun 07, 2005 6:59 am

Hibernate version: 3

Hello. How can I session.load() a concrete subclass if I know the ID and not the concrete subclass? I use Table per subclass mapping.

I have 3 classes: Widget (abstract superclass) and subclasses WidgetPicture and WidgetLine.

Code:

Widget widget = (Widget) session.load(Widget.class, id);
// now widget contains proxy class and it can't be retyped to a concrete subclass
// this (ugly) hack will retrieve the correct subclass:
Widget widget = (Widget) session.load(session.getEntityName(widget), id);

The second line moreover generates a warning:

Code:

WARN  PersistenceContext - Narrowing proxy to class com.kovine.kfe.dao.WidgetPicture - this operation breaks ==

So, what I need is to load a concrete subclass but I know only the ID, not the concrete subtype. I've found in the hibernate forums similar problems, but not one solving this issue.

Gurus, please help me and you'll get to the heaven :)
Martin

zdila · **Posted:** Tue Jun 07, 2005 7:02 am

fix: second line doesn't contain declaration (of course):

Code:

Widget widget = (Widget) session.load(Widget.class, id);
widget = (Widget) session.load(session.getEntityName(widget), id);

zdila · **Posted:** Tue Jun 07, 2005 8:09 am

Code:

<hibernate-mapping default-lazy="false">

helped, but I'd like to have my class lazy. Pls help.

max · **Posted:** Tue Jun 07, 2005 9:12 am

use get or a query.list() but you can still get the issue if you have already loaded the "non-castable" proxy before in the session.

zdila · **Posted:** Tue Jun 07, 2005 9:25 am

Thanks max! It works. Unfortunately I can't find this feature in the documentation (only http://www.hibernate.org/hib_docs/v3/reference/en/html/objectstate.html#objectstate-loading) but nevermind.
Please look at the http://forum.hibernate.org/viewtopic.php?t=943445 yet.

--
Martin