Mapped collections and paged query results?

trancer_hibernate · **Joined:** Wed Sep 20, 2006 6:33 am **Posts:** 5

Hibernate version: 3.1

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Hello.

I have a question regarding mapped collections and paged query results. I would even say mapped collections vs paged query results. Let me describe my problem.
Say I have an entity User which has a collection of DVDs. In the mapping for a User I would write:

Code:

   <class name="my.User" table="user">
      <set name="DVDs" lazy="true">
         <key column="id_user"/>
         <one-to-many class="my.DVD"/>
      </set>
   </class>

Then if I need a User's collection of DVDs I would write

Code:

List dvds = user.getDVDs();

But in this case I would get all the DVDs that a user has.
Consider a situation where a user has a lot of DVDs and I want to page them (DVDs) for a client. I do not want a client to get 15000 DVDs list on one page.
So to create a page of results of a user's DVDs I would make a query like this:

Code:

Query query = session.createQuery("from DVD where id_user = ?").setLong(0, user.getId());
// go to desired page, and fetch the page of results
List dvds = query.setFirstResult(page * pageSize).setMaxResults(pageSize + 1).list();

So the question is: If I know beforehand that my users will have a lot of DVDs and I will always be paging results do I need the collection mapping at all? Or may be there are ways to use mapped collections and paging results together?

Thanks in advance!

max · **Posted:** Wed Sep 20, 2006 7:10 am

no need for mapping collections you don't use or have.