Query with multiple classes - how?

mlerutte · **Posted:** Fri Oct 24, 2003 3:06 pm

(I've send this message to the development list too, it doesn't belong there. Mea Culpa.)

The Hibernate documentation states in chapter 9 (Hibernate Query Language)

"Multiple classes may appear, resulting in a cartesian product or "cross" join.

from Formula, Parameter

from Formula as form, Parameter as param"

A bit later something similar:
"select cat, count( elements(cat.kittens) ) from eg.Cat cat group by cat"

It is not clear to me what the result of such a query would be. What type would be the contents of the objects contained by
the collection returned by the query's list() or iterate() methods.

For example let's assume I've executed the "cat" query:

Code:

session = ...
query = session.getNamedQuery("Cat_and_kitten_count");
 
iterator = query.iterate();
 
while (iterator.hasNext()) {
Object element;
 
element = iterator.next();
// what type is element?
// How to get the cat and the kitten count?
}

At the moment I don't have an infrastructure to try this easily on and this problem is nagging my mind...

Maurice.

christian · **Posted:** Fri Oct 24, 2003 3:32 pm

A collection of Object[], where index 0 is a Cat and index 1 is an
Integer.

max · **Posted:** Fri Oct 24, 2003 4:04 pm

...Hibern8IDE is a great thing for such explorations ;)

(just so ya'know ;)

kbrown · **Joined:** Mon Oct 20, 2003 3:03 pm **Posts:** 13

Jython (http://www.jython.org) is a JVM scripting language that can be run interactively (i.e., gives immediate feedback) that I find invaluable for testing HQL:

>>> import net.sf.hibernate as hibernate

>>> sf = hibernate.cfg.Configuration().configure("/my.hibernate.cfg.xml").buildSessionFactory()

>>> sess = sf.openSession()

>>> rs=sess.find("select x from x in class BasePlanTerritory")

>>> rs
[com.revenuetech.mpi.beans.BasePlanTerritory@14b3a9e[terrId=1], com.revenuetech.
mpi.beans.BasePlanTerritory@b7b6ef[terrId=4], com.revenuetech.mpi.beans.BasePlan
Territory@17e4c97[terrId=5]]

>>> [x.name for x in rs]
['Corporate', 'Filters', 'Ride Control']

gavin · **Posted:** Fri Oct 24, 2003 4:49 pm

Dude, Hibern8ide now has a beanshell for doing this kind of stuff. Try it, its great.

mlerutte · **Posted:** Sat Oct 25, 2003 5:56 am

[quote="max"]...Hibern8IDE is a great thing for such explorations ;)

(just so ya'know ;)[/quote]

I've looked at the site and it certainly looks promising! I'll try it out. Thanks for the link.