We've been using Hibernate for quite some time in JLCP but we've had a problem with the paging of results in any collection. The code we're using for collection paging is the following:

List topicList = null;
Session session = null;

try
{
session = this.sessionManager.getHibernateSession();
String query = "from topic in class org.jlcp.module.forum.model.Message where topic.parentMessage is null and topic.approved=true and topic.category="+category.getId() + " order by topic.creationDate desc";
Query q = session.createFilter(topicList, query); // the trivial filter
q.setMaxResults(perPage);
// Substract one from the page so we can enter pages 1-infinity, but
// but first result is 0-(infinity-1)
q.setFirstResult(perPage * (page-1));
topicList = q.list();
}
catch (HibernateException he)
{
throw new PersistenceException(he);
}
finally
{
this.sessionManager.flushCommitCloseSession(session);
}

This code generates the following exception each time it runs:

org.jlcp.infrastructure.persistence.exceptions.PersistenceException: net.sf.hibernate.TransientObjectException: Collection was not yet persistent
at org.jlcp.module.forum.provider.hibernate.dao.CategoryDAO.getModeratedTopics(CategoryDAO.java:255)
at org.jlcp.module.forum.ForumManager.getModeratedTopics(ForumManager.java:81)
at org.jlcp.module.forum.web.taglib.topic.HasTopics.doStartTag(HasTopics.java:78)

....

Caused by: net.sf.hibernate.TransientObjectException: Collection was not yet persistent
at net.sf.hibernate.impl.SessionImpl.getFilterTranslator(SessionImpl.java:3381)
at net.sf.hibernate.impl.SessionImpl.filter(SessionImpl.java:3415)
at net.sf.hibernate.impl.FilterImpl.list(FilterImpl.java:42)
at org.jlcp.module.forum.provider.hibernate.dao.CategoryDAO.getModeratedTopics(CategoryDAO.java:251)


Any help here would be great, as its really killing me!

Thanks in advance,
Matt
matt@javalobby.org

Collection filters are only for persistent collections, ie. for collections that are properties of an entity associated with the session.

So is there any way to do this with non-persistant collections? I suppose we could do it on the topics in a forum if those topics were a set on the category object itself?

correct.