Hi: I am using HQL to retrieve a graph of object but getting classcast exception.

Class A {
Set<B> b
Set<C> c
}

List <A> result = session.createQuery("from A a left outer join a.b where a.id = 1234").list();

I am using Hibernate 3.3.2 with JDK 1.6. Can some shed some light what could be the reasons.

Regards,
RJ.

I think you need to specify 'select a from A a ....' otherwise the default is to include joined entities as well. The query you posted is the same as 'select a, b from A a ...' which is returned as a List<Object[]>.

Thanks borg for the response and the query worked like you suggested.

But I also able to make it work by doing this (see the code below), note the use of key word "fetch"; and I wonder is there any difference between the 2 approaches. If I picked it right from Hibernate reference document fetch forced an outer join and try to fetch all the records with a single select.

("from A a left outer join fetch a.b where a.id = 1234").list()