help! problem with one to mamy

ebrmp · **Joined:** Wed Mar 03, 2004 10:26 am **Posts:** 2

When I using hibernate update talbe,the parent table can be updated succesful,but the child table only do insert,can't update the old records

Parent.hbm.xml

Code:

<hibernate-mapping>
<class name="com.websh.hibernate.model.Parent" table="parent" dynamic-update="true" dynamic-insert="true">
<id column="parentid" name="parentid" type="java.lang.Long">
<generator class="increment"/>
</id>
<property column="parentname" length="50" name="parentname" type="java.lang.String"/>

        <bag name="childs" cascade="all" inverse="true" >
            <key column="parentid"/>
            <one-to-many class="com.websh.hibernate.model.Child"/>
        </bag>

</class>
</hibernate-mapping>

Child.hbm.xml

Code:

<hibernate-mapping>
<class name="com.websh.hibernate.model.Child" table="child" dynamic-update="true" dynamic-insert="true">
<id column="childid" name="childid" type="java.lang.Long">
<generator class="increment"/>
</id>


<property column="childname" length="50" name="childname" type="java.lang.String"/>

<many-to-one name="parent" class="com.websh.hibernate.model.Parent" not-null="true" column="parentid"/>

</class>
</hibernate-mapping>

Child.java

Code:

  public Parent getParent() {
    return parent;
  }

  public void setParent(Parent parent) {
    this.parent = parent;
  }

Parent.java

Code:

    public Collection getChilds() {
      if (childs==null){
        childs = new ArrayList();
      }
        return this.childs;
    }

    public void setChilds(Collection childs) {
        for (Iterator iter = childs.iterator(); iter.hasNext(); ) {
          Child item = (Child)iter.next();
          item.setParent(this);
        }
        this.childs = childs;
    }

method

Code:

  public static void update(){
    Collection col = new ArrayList();
    try{
      Configuration cfg = new Configuration().configure();
      SessionFactory sessions = cfg.buildSessionFactory();
      Session session = sessions.openSession();
      Transaction tx = session.beginTransaction();

      Child c = new Child();
      for (int i = 0; i < 3; i++) {
        c.setChildname("儿子up"+i);
        col.add(c);
      }
      Parent p = new Parent();
       p = (Parent)session.load(Parent.class, new Long(1));

      p.setChilds(col);
      p.setParentname("a");

      session.update(p);
      session.flush();
      tx.commit();
      session.close();
    }catch(Exception e){
      e.printStackTrace();
    }
  }

michael · **Posted:** Wed Mar 03, 2004 10:52 am

Well I don't see you doing an update of a child in your code anywhere ...

ebrmp · **Joined:** Wed Mar 03, 2004 10:26 am **Posts:** 2

Shoule I update the childs manual?
I think if I use one to many ,when I update the parents, the childs will be updated automatic.

thank for your reply.

jlawmi · **Joined:** Mon Nov 24, 2003 6:36 pm **Posts:** 105

suggestion- don't "set" the children,- get a handle to the collection, then add/remove/update using the existing collection. When you load your parent object, just call
parent.getChildren().add (for an insert)
or for an update
iterator it = parent.getChildren().
while (it.next())
{
//find the object needing update
//and modify existing object in this collection
Child child = (Child) it.next();
if (child.getId().equals("one needing update")
child.setXXX()

}
instead of
parent.setChildren(some new collection)

I'm not sure this is the problem, but the example in the docs explains it in a way that suggests adding/removing from the existing collection, not replacing with a new collection.

check out 9.2 in the manual...

James

jaynes · **Posted:** Thu Mar 04, 2004 8:25 am

Given your update method, it acts exactly as it should. You create a collection three new children, set their names, but their childid's are left null. You load the parent and set the new collection for the children, then you update the parent. Hibernate sees that the parent has three new children (ids are null) and inserts them.

If you want to update existing children then load the parent, loop through the children and change them, then update the parent.

Will

emmanuel · **Posted:** Fri Mar 05, 2004 5:12 am

In your sample you don't update your child objects, you insert them (they"re new)