Denormalize grandparent's id in grandchildren

melicin · **Joined:** Mon Jun 12, 2006 7:25 pm **Posts:** 7

Hi,

Can someone tell me if it's possible to pull grandparent's generated id and have it persisted in the grandchild. Here is the scenario:

GrandParent->Parent->Child

Each class declares a generated id as primary key:
<class name="GrandParent">
<id name="grandParentId" column="GRANDPARENT_ID">
<generator class=.../>
</id>
...
</class>

<class name="Parent">
<id name="parentId" column="PARENT_ID">
<generator class=.../>
</id>
...
</class>

<class name="Child">
<id name="childId" column="CHILD_ID">
<generator class=.../>
</id>
...
</class>

I already have a bi-directional collection mapping from Parent to Child:

<bag name="children" lazy="false" inverse="true">
<key column="PARENT_ID"/>
<one-to-many class="Child" />
</bag>

And the child has the many-to-one mapping:

<many-to-one name="customer" column="PARENT_ID" class="Parent" not-null="true"/>

I'd like the GRANDPARENT_ID column added to the Child and persisted as part of the collection mapping from Parent to Child. Is this possible?

Thanks,
Ali

dominicus · **Posted:** Wed Jan 03, 2007 5:12 am

Maybe it could be useful to use the formula attribute for the property element :

from the documentation :

Code:

<property
        name="propertyName"                                          (1)
        column="column_name"                                         (2)
        type="typename"                                              (3)
        update="true|false"                                          (4)
        insert="true|false"                                          (4)
        [b]formula="arbitrary SQL expression" [/b]                          (5)
        access="field|property|ClassName"                            (6)
        lazy="true|false"                                            (7)
        unique="true|false"                                          (8)
        not-null="true|false"                                        (9)
        optimistic-lock="true|false"                                 (10)
        generated="never|insert|always"                              (11)
        node="element-name|@attribute-name|element/@attribute|."
        index="index_name"
        unique_key="unique_key_id"
        length="L"
        precision="P"
        scale="S"
/>

Javier Martinez · **Posted:** Wed Jan 03, 2007 5:29 am

I advice to see the Hibernate in Action Book (Manning), in the page 103 is the solution for this cases. You should use a joined-subclass tag with a key tag. It is really complex for explain in a forum, but I hope to be helping you.

You could read the reference documentation in the joined-subclass topic, and inheritance class mapping.

Regards.