<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping
>
    <class
        name="fr.xx.model.FilterChain"
        table="FILTERCHAIN"
        dynamic-update="true"
    >

        <id
            name="id" column="id" type="java.lang.Long" unsaved-value="0">
            <generator class="sequence"/>
        </id>

        <property name="comment" type="text" update="true" insert="true" column="comment" not-null="false"/>

        <property name="date" type="java.util.Date" update="true" insert="true" column="date" not-null="true"/>

      <!-- from http://forum.hibernate.org/viewtopic.php?t=943384 -->
        <list name="filters"
            lazy="true"
            inverse="false"
            cascade="all,delete-orphan"
        >
            <key column="chain_id" not-null="true" update="false"/>
            <list-index column="forder" />
            <one-to-many class="fr.xx.model.AbstractFilter"/>
        </list>

        <property name="name" type="java.lang.String" update="true" insert="true" column="name" not-null="true" unique="true"/>

        <property name="owner" type="java.lang.String" update="true" insert="true" column="owner" not-null="true"/>
    </class>

</hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping
>
    <class name="fr.xx.model.AbstractFilter" table="FILTER" discriminator-value="A">
        <cache usage="read-write" />

        <id name="id" column="id" type="java.lang.Long" unsaved-value="0">
            <generator class="sequence"/>
        </id>

        <discriminator column="TYPE" type="string" />
   
        <many-to-one
            name="key"
            class="fr.xx.model.DefaultLabelKey"
            cascade="none"
            fetch="select"
            update="true"
            insert="true"
            column="key_id"
            not-null="true"
            lazy = "false"           
        />

      <!-- from http://forum.hibernate.org/viewtopic.php?t=943384 -->
        <many-to-one name="chain"
            column="chain_id"
            class="fr.xx.model.FilterChain"
            not-null="true"
            insert="false"
            update="false"
        />

      <!-- read-only property used by hibernate to manage list order  -->
      <property name="forder" column="forder" type="int" insert="false" update="false" not-null="true"/>
      
        <subclass
            name="fr.xx.model.GroupFilter"
            discriminator-value="G"
        />
       
        <subclass
            name="fr.xx.model.ReduceFilter"
            discriminator-value="R"
        >
        <property name="revert" type="boolean" update="true" insert="true" column="revert"/>
        <property name="value" type="java.lang.String" update="true" insert="true" column="value" />

      </subclass>

    </class>

</hibernate-mapping>

Hibernate: insert into FILTER (key_id, chain_id, forder, revert, value, TYPE, id) values (?, ?, ?, ?, ?, 'R', ?)
Hibernate: update FILTERCHAIN set comment=?, date=?, name=?, owner=? where id=?
Hibernate: update FILTER set key_id=?, revert=?, value=? where id=?
Hibernate: update FILTER set key_id=?, revert=?, value=? where id=?

...
create table FILTER (id int8 not null, TYPE varchar(255) not null, key_id int8 not null, chain_id int8 not null, forder int4 not null, revert bool, value varchar(255), primary key (id));
create table FILTERCHAIN (id int8 not null, comment text, date timestamp not null, name varchar(255) not null unique, owner varchar(255) not null, primary key (id));
alter table FILTER add constraint FK7B9BBF78599119ED foreign key (key_id) references LABELKEY;
alter table FILTER add constraint FK7B9BBF78CFBD0B48 foreign key (chain_id) references FILTERCHAIN;

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping
>
    <class
        name="fr.xx.beans.FilterChain"
        table="FILTERCHAIN"
        dynamic-update="true"
    >

        <id
            name="id" column="id" type="java.lang.Long" unsaved-value="0">
            <generator class="sequence"/>
        </id>

        <property name="comment" type="text" update="true" insert="true" column="comment" not-null="false"/>

        <property name="date" type="java.util.Date" update="true" insert="true" column="date" not-null="true"/>

      <!-- from http://forum.hibernate.org/viewtopic.php?t=943384 -->
        <list name="filters"
            lazy="true"
            inverse="false"
            cascade="all,delete-orphan"
        >
            <key column="chain_id" not-null="true" update="false"/>
            <list-index column="forder" />
            <one-to-many class="fr.xx.beans.AbstractFilter"/>
        </list>

        <property name="name" type="java.lang.String" update="true" insert="true" column="name" not-null="true" unique="true"/>

        <property name="owner" type="java.lang.String" update="true" insert="true" column="owner" not-null="true"/>
    </class>

</hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-mapping PUBLIC
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping
>
    <class name="fr.xx.beans.AbstractFilter" table="FILTER" discriminator-value="A">
        <cache usage="read-write" />

        <id name="id" column="id" type="java.lang.Long" unsaved-value="0">
            <generator class="sequence"/>
        </id>

        <discriminator column="TYPE" type="string" />
   
        <many-to-one
            name="key"
            class="fr.xx.beans.DefaultLabelKey"
            cascade="none"
            fetch="select"
            update="true"
            insert="true"
            column="key_id"
            not-null="true"
            lazy = "false"           
        />

      <!-- from http://forum.hibernate.org/viewtopic.php?t=943384 -->
        <many-to-one name="chain"
            column="chain_id"
            class="fr.xx.beans.FilterChain"
            not-null="true"
            insert="false"
            update="false"
        />
      
        <subclass
            name="fr.xx.beans.GroupFilter"
            discriminator-value="G"
        />
       
        <subclass
            name="fr.xx.beans.ReduceFilter"
            discriminator-value="R"
        >
        <property name="revert" type="boolean" update="true" insert="true" column="revert"/>
        <property name="value" type="java.lang.String" update="true" insert="true" column="value" />

      </subclass>

    </class>

</hibernate-mapping>

<!-- from http://forum.hibernate.org/viewtopic.php?t=943384 -->
<!-- from hibernate doc http://www.hibernate.org/hib_docs/v3/reference/en/html/associations.html#assoc-bidirectional-m21 -->
        <list name="filters"
            lazy="true"
            inverse="false"
            cascade="all,delete-orphan"
        >
            <key column="chain_id" not-null="true" update="false"/>
            <list-index column="forder" />
            <one-to-many class="fr.xx.AbstractFilter"/>
        </list>

<!-- from http://forum.hibernate.org/viewtopic.php?t=943384 -->
        <many-to-one name="chain"
            column="chain_id"
            class="fr.xx.FilterChain"
            not-null="true"
            insert="false"
            update="false"
        />

        <list name="filters" cascade="all,delete-orphan">
            <key column="chain_id" not-null="true" update="false"/>
            <list-index column="forder" />
            <one-to-many class="fr.xx.AbstractFilter"/>
        </list>

       <many-to-one name="chain"
            column="chain_id"
            class="fr.xx.FilterChain"
            not-null="true"
            insert="false"
            update="false"
        />

Hibernate: update FILTERCHAIN set comment=?, date=?, name=?, owner=? where id=?
Hibernate: update FILTER set key_id=?, revert=?, value=? where id=?
DEBUG main org.hibernate.persister.collection.AbstractCollectionPersister - Updating rows of collection: fr.xx.FilterChain.filters#1
DEBUG main org.hibernate.persister.collection.AbstractCollectionPersister - done updating rows: 0 updated
Hibernate: delete from FILTER where id=?

List filters = c.getFilters();
      
Assert.assertNotNull(filters);
Assert.assertEquals(2, filters.size());      

IFilter filterToRemove =  (IFilter) filters.get(0);
      
c.removeFilter(filterToRemove);
      
getFilterChainDao().save(c);

actualTable = getConnection().createQueryTable( "FILTER", "SELECT forder FROM FILTER" );
      
assertEquals("first filter forder",0, actualTable.getValue(0, "forder"));      

        <list name="filters" cascade="all,delete-orphan">
            <key column="chain_id" not-null="true"/>
            <list-index column="forder" />
            <one-to-many class="fr.xx.AbstractFilter"/>
        </list>

       <many-to-one name="chain"
            column="chain_id"
            class="fr.xx.FilterChain"
            not-null="true"
            insert="false"
            update="false"
        />

    <list name="filters" cascade="all,delete-orphan">
      <key column="chain_id" /> 
      <list-index column="forder"/> 
      <one-to-many class="fr.xx.AbstractFilter"/>
    </list>

    <many-to-one name="chain" column="chain_id" 
         class="fr.xx.FilterChain"
    />

My problem is deletions show in the log, but dont happen in the database.
For whatever reason, the fix is to use a transaction in the code.

My tables are parent 1 to 0+ child.

parent
-------
parent_id (PK)

child
-----
child_id (PK)
parent_id (not null)


Here's the hibernate config:

    <many-to-one name ="parent"
                 class   ="Parent"
                 column  ="parent_id"
                 insert  ="false"
                 update  ="false"
                 not-null="true" />

    <set name   ="child" >
        <key column  ="parent_id"
             not-null="true" />
        <one-to-many class="Child" />
    </set>

Here's the code:

    Session session = HibernateUtil.currentSession();
    session.beginTransaction();

    q =session.createQuery(query);
    parent = q.list().iterator().next()
    child = parent.getChildren().iterator().next();

    child.setParent(null);
    parent.getChildren().remove(child);
    session.delete(child);

    HibernateUtil.commitTransaction();
    HibernateUtil.closeSession();

Be sure to enable sql logging:

<hibernate-configuration>
    <session-factory>
        <property name="show_sql">true</property>

The console logging shows roughly this:

    from parent
    left outer join child
    where parent_id = ?

    select parent_id
    from child
    where child_id = ?

    delete
    from child
    where child_id = ?

Here's where the problem occurs.
The hibernate logging shows a deletion query.

My guess is there's an exception that's swallowed somewhere.
I'm using an older version of hibernate, this may be solved already:
    1971632 Aug 21 10:29 hibernate3.jar

This fix for me, is replace this java code:
    session.delete(child);
with this:
        Transaction tx = null;
        try {
            tx = session.beginTransaction();
            session.delete(child);
            tx.commit();
        }
        catch (HibernateException e) {
            try {
                if (tx != null)
                    tx.rollback();
            } catch (Exception ee) {}

            System.out.println("Exception deleting object:" + e);
        }


I found several combinations of hibernate configurations that would work.
Some of them included the middle logging output of:
    select parent_id
while others just output the first and 3rd sql.
If you are not getting a hibernate or sql exception,
then this post might be for you:)

If you have:
    cannot update (child.child_id) to NULL
that's a config error, and is answered above and in the other links.


jkuipers post seems to be about the same issue:
http://forum.hibernate.org/viewtopic.php?t=943384


Thanks to meshenka and others for gathering lists of related posts.
These helped me.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
      "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping auto-import="true" default-lazy="false">

   <class name="AddressLocation" table="locations">
      <id name="id" column="id">
         <generator class="native"/>
      </id>   
      
      
      <component name="address" class="Address">
            <property name="street" type="string">
                <column name="street"/>
            </property>
            <property name="city" type="string">
                <column name="city"/>
            </property>
            <property name="state" type="string">
                <column name="state"/>
            </property>   
                   
       </component>   

        <many-to-one name="person" column="person_id" class="Person" ></many-to-one>
       
   </class>
   
   <class name="Person" table="person" >
      <id name="id" column="id" type="integer">
         <generator class="native"/>
      </id>
      <property name="name" column="name"/>
      
<list name="address" inverse="true" cascade="all-delete-orphan">
         <key column="person_id" not-null="true"/>
         <list-index column="idx"/>
         <one-to-many class="AddressLocation"/>
      </list>
      
   </class>
   
</hibernate-mapping>