Hibernate list persistance

[Pablo M�ller]

Hi,
I'm building a word processor that has a version control and saves each paragraph to the database. One version is composed by several paragraphs. A new version is created each time Users enters the editor, and each time they save the document it is saved to the same version, until they access the editor again.
The problem is that the paragraphs are only saved properly te first time. Any further save, will save the version and the paragraps but not the relation between them. So any paragraph created after the first save is persisted, but cannot be retrieved, since it's not associated to the version.

Here's the mapping:

    
 <class name="wuw.model.Paragraph" table="paragraphs">
    <id name="id" type="long">
    <generator class="native"/>
    </id>
    <property name="content"></property>
    </class>
   
    <class name="wuw.model.Version" table="versions">
    <id name="id" type="long">
<generator class="native"/>
    </id>
    <property name="creationDate" column="creation_date"/>
<property name="versionNumber" column="version_number"/>
<many-to-one name="user" class="wuw.model.User"/>
    <list name="paragraphs" table="version_paragraphs" cascade="persist,merge,save-update"> 
<key column="version_id"/>
<list-index column="position"/>
<many-to-many class="wuw.model.Paragraph" column="paragraph"/>
</list>
    </class>

Here's the code that saves:

....
Version v = ed.getVersion();
List<Paragraph> pars = new ArrayList<Paragraph>();
for (int j=0; j<ps.size(); j++ )
{
     Paragraph p = new Paragraph();
     p.setContent((String)ps.get(j));
     Paragraph.getDao().save(p);
     pars.add(p);
}
v.setParagraphs(pars);
v.setCreationDate(new Date());
v.setUser(u);
 
if (v.getId()==null)
{//If it is a new version (first save)
        Version.getDao().save(v);
}
else
{//for 2nd+ saves
Version.getDao().update(v);
}

And finally here's the dao code

 
protected void save(Object o)
{
    getSession().saveOrUpdate(o);
}

protected void update(Object o)
{
Object obj = getSession().merge(o);
save(obj);
}   

If anyone knows what's the problem it would be great.
Thanks,
Pablo.