problem with one-to-many relation

ojojoj · **Joined:** Wed Dec 07, 2005 6:31 am **Posts:** 9

Hi!

I'm a hibernate newbie and I'm getting some strange results with a one-to-many relation, relating an object to childobjects of the same class. My one-to-many Set seems to contain only 1 object, even though I know for a fact it's supposed to contain several. If I change the Set into a List, I get all objects but the list also contains several "Null"-values.

Code:

My table:
-----------
id     name                           skill_id
1      node with 3 childnodes        <NULL>
2      a node                         1 
3      node with 1 childnode          1
4      another node                   1
5      last node                      3

Code:

My mapping :
-----------------
<hibernate-mapping package="modules.skills">
    <class name="Skill" table="Skill" lazy="true">
        <id name="id" column="id" type="java.lang.Integer">
            <generator class="native"/>
        </id>
        <property name="name" column="name" type="java.lang.String"/>
        <set name="subskills" lazy="true" inverse="true">
            <key column="Skill_id"/>
            <one-to-many class="modules.skills.Skill"/>
        </set>
        <many-to-one name="parent" column="Skill_id" class="modules.skills.Skill"/>
    </class>
</hibernate-mapping>

Code:

My class:
------------
public class Skill {

    private int id;
    private String name;
    private Integer skill_id;
    private Set subskills;
    private Skill parent;
    
    public Skill() {}
    
    setters&getters

Code:

My code :
------------
        Iterator it = con.getClientHibernateSession().createQuery( "from modules.skills.Skill as Skill").list().iterator();
        while( it.hasNext() ) {
            Skill skill = (Skill)it.next();
            System.out.println("name :" + skill.getName() );
            System.out.println("children :" + skill.getSubskills().size());
            Set l = skill.getSubskills();
            for (Object o : l) {
                Skill t = (Skill)o;
                if(t!=null) {
                    System.out.println( "-->" + t.getName());
                }
                else {
                    System.out.println("-->null");
                }
            }
            if( skill.getParent()!=null ) {
                System.out.println("parent : " + skill.getParent().getName());
            }
            System.out.println("");
        }

Code:

My output:
-------------
name :node with 3 childnodes
children :1
-->a node

name :a node
children :0
parent : node with 3 childnodes

name :node with 1 childnode
children :1
-->last node
parent : node with 3 childnodes

name :another node
children :0
parent : node with 3 childnodes

name :last node
children :0
parent : node with 1 childnode

Any ideas?

ojojoj · **Joined:** Wed Dec 07, 2005 6:31 am **Posts:** 9

My skill class was extending some old abstract class that overrode equals(), hashCode() and compareTo(). These methods doesn't seem to work with hibernate, and my results became as expected when I removed the overrides.

I still get the NULL-values in my List, but I guess I can live with the Set for now.

Anyone had similar problems with the List?

OJ