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flam70
 Post subject: Retrieve collection child from a parent
PostPosted: Thu Dec 11, 2003 6:08 am 
Beginner
Beginner

Joined: Thu Oct 02, 2003 8:02 am
Posts: 45
I have 2 classes User and Event with a one-to-many monodirectionnal association.
Code:
public class User
{
     private Set events;
     //...
}

Given a user (eg u), i would like to retrieve all his events.
I use MySQL.
I write the following request inside find method :
Code:
session.find("select elements(user.events) from User user where user=?",u,Hibernate.entity(User.class))


But MySQL version does not support sub-queries.
what kind of hibernate query can i write to do so ?
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flam70
 Post subject:
PostPosted: Thu Dec 11, 2003 8:54 am 
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Joined: Thu Oct 02, 2003 8:02 am
Posts: 45
This is the good version of my question.
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dimas
 Post subject:
PostPosted: Thu Dec 11, 2003 10:46 am 
Expert
Expert

Joined: Tue Sep 16, 2003 4:06 pm
Posts: 318
Location: St. Petersburg, Russia
Why can't you just call user.getEvents() and let Hibernate do the job?
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flam70
 Post subject:
PostPosted: Thu Dec 11, 2003 11:00 am 
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Joined: Thu Oct 02, 2003 8:02 am
Posts: 45
OK but does user.getEvents() must be called in a session ?
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michael
 Post subject:
PostPosted: Thu Dec 11, 2003 11:04 am 
Hibernate Team
Hibernate Team

Joined: Tue Sep 09, 2003 2:10 pm
Posts: 3246
Location: Passau, Germany
If it is lazyly initialized, yes. If you have loaded the User Object in another Session, you can reassociate it with the new session by using session.lock(user, LockMode.NONE)
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dimas
 Post subject:
PostPosted: Thu Dec 11, 2003 11:06 am 
Expert
Expert

Joined: Tue Sep 16, 2003 4:06 pm
Posts: 318
Location: St. Petersburg, Russia
What does it mean "in a session" ?
In any case, user.getEvents() does not require Session as argument. Depending on your mapping (namely, "lazy" attribute of this <set>) you may need that session in which User object was loaded remain open when you call user.getEvents.
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flam70
 Post subject:
PostPosted: Thu Dec 11, 2003 11:11 am 
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Joined: Thu Oct 02, 2003 8:02 am
Posts: 45
In fact, the user is store in a HttpSession Object and hibernate session in which user has been loaded is close. So if i retrieve user from HttpSession and create a new hibernate session, will user.getEvents() works ?
For information, i set lazy attribute to 'true"
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michael
 Post subject:
PostPosted: Thu Dec 11, 2003 11:12 am 
Hibernate Team
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Joined: Tue Sep 09, 2003 2:10 pm
Posts: 3246
Location: Passau, Germany
As I said, use session.lock(user, LockMode.NONE) with the new session
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