Suppose ClassA may contain zero or more ClassB



ClassA may contain a lot of ClassB , and I only want to load the latest ClassB ,
or sort ClassB to get prior N objects. (ClassB implements Comparable)
I looked up the manual , it seems no way to limit the number of returned ClassB.

I know HQL can limit the number of returned rowsets by Query.setMaxResults(int maxResults)
But in this case , ClassA.getClassBSet() is automatically loaded by hibernate , how does HQL step in ?

Thank you.

This is a FAQ.


Use a collection filter.

Hi , but this will make my domain object dependent of Hibernate ...


Is it possible to make my domain object as 'clean' as this ?

I don't want to add hibernate-dependent code in get/setClassBSet(), I hope this is automatically set by hibernate , it it possible ?

Hi , this is how I make use of collection filter :


It really filters out what I want , but ...I have one question .
In the first println() , hibernate still gets all ClassB's instances ,
meaning that upon session.load(ClassA,class , key) , hibernate still loads all ClassB.
I am afread that if there are a lot of ClassB , it will out of memory...
Is it possible to set filter before load ClassA ?

Well, obviously you shouldn't do the first println!!!


LOL.


it is the toString() method that is causing the lazy collection to be initialized.

actually the call to size()

So , if ... if I don't do the first println() , hibernate will not load all ClassB ?

As long as you map the collection with lazy="true"