ClassCastException: what does join return?

tcn · **Joined:** Tue Mar 23, 2004 4:18 pm **Posts:** 45

Hi!

I ran a

"SELECT urls.url, urls.id, html.html FROM f4t.hibernate.Url as urls JOIN urls.html as html" and expected to get Url objects, but casting to Url does actually throw an ClassCastExceptin (html.urlid is FK to urls.id):

Code:

Iterator iter = session.iterate(query);
while( iter.hasNext() )
{
   Url o= (Url)iter.next();   // ClassCastException
   System.out.println(o);
}

Well, what does my query return actually?

christian · **Posted:** Sat Jun 05, 2004 8:50 am

Collection of Object[], you are using projection.

tcn · **Joined:** Tue Mar 23, 2004 4:18 pm **Posts:** 45

And what would I have to do to actually get Url objects (I assume this would incorporate fetching all columns?)?

tcn · **Joined:** Tue Mar 23, 2004 4:18 pm **Posts:** 45

christian wrote:

Collection of Object[], you are using projection.

Can I somehow get a col name to array index mapper? What if somebody changes the sequence or does add/remove columns to the query?

christian · **Posted:** Sat Jun 05, 2004 10:27 am

Please read about the "select" clause in the Hibernate documentation.

tcn · **Joined:** Tue Mar 23, 2004 4:18 pm **Posts:** 45

I did

SELECT urls FROM f4t.hibernate.Url as urls JOIN urls.html as html"
WHERE urls.url LIKE 'http://%'"

But this leads to numerous SELECT query executed :-( I played with use_outer_join but this made thing even worse.

steve · **Posted:** Sat Jun 05, 2004 12:22 pm

Without any of your mappings, we can only guess. But I think a safe guess is that you have all your associations defined as non-lazy. Please read the documentation!