One-to-many Foreign Key Association

dlandis · **Joined:** Mon Jul 03, 2006 12:59 pm **Posts:** 6

With a one-to-many association where the primary key of the parent maps to part of the primary key of the children, how do you save the children??

The problem is the primary key is genereted by a sequence, so the corresponding field will not be set in the children objects -- it will be null at the time of insert.

Since it is null, the rows cannot be inserted with a partially null primary key. How to people solve this; I imagine it is fairly common????

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

Code:

<class name="Parent" ...>
  <id column="ParentID" ...>
  ...
  <set name="Children" inverse="false">
    <key name="ParentID" not-null="true"/>
    <one-to-many class="Child"/>
  </set>
  ...
</class>

<class name="Child" ...>
  <composite-id>
    <key-property name="ChildID" .../>
    <key-many-to-one name="Parent" class="Parent" column="ParentID"/>
  </composite-id>

  ...
</class>

You can also make the composite-id named. See section 5.1.5 of the ref docs.