lookup "composite key" objects on the session

oper2000 · **Joined:** Thu Aug 28, 2003 7:14 am **Posts:** 18

I am using Hibernate 2.1,
how can I find out if there is an instance of some persistent object associated with the session? The class has COMPOSITE KEY.
thanks,
MIchael

anthony · **Posted:** Tue Mar 16, 2004 9:46 am

session.load(class, serializable) look at javadoc
for composite id, a best practice is to have a class reprenting the composite id. This class must implements serializable so you can also use it for session.load

shl · **Posted:** Tue Mar 16, 2004 10:01 am

delpouve wrote:

session.load(class, serializable) look at javadoc
for composite id, a best practice is to have a class reprenting the composite id. This class must implements serializable so you can also use it for session.load

from the javadoc
You should not use this method to determine if an instance exists (use find() instead). Use this only to retrieve an instance that you assume exists, where non-existence would be an actual error.
use the following approach:

Code:

Integer count =
    (Integer)session.find("count(obj) from YourClass obj where obj.id.key1=val1 AND obj.id.ke2=val2").iterate().next();

anthony · **Posted:** Tue Mar 16, 2004 10:14 am

shl is right,
i misunderstood the initial question, i thought you wanted to retrieve and object from the session ( that is to say, you know the object is in the session...)

oper2000 · **Joined:** Thu Aug 28, 2003 7:14 am **Posts:** 18

no delpouve, actually you are right since that was exactly my question.
thanks ALL

anthony · **Posted:** Tue Mar 16, 2004 10:25 am

everybody is right , that's cool :)

emmanuel · **Posted:** Wed Mar 17, 2004 10:36 am

Eheh! After Xtrem Programming, now Xtrem Supporting :)