Question

I am trying to save a record which has a many-to-one property mapping. I attempt to assign a newly created parent object here (or use an existing, but that works fine) but I get an error when it tries to add the ID of the parent object to the child’s table. Saying it cannot add NULL to the table, which is true, but I thought nHibernate was clever enough to save the parent object first, even if I am adding the child.

Mappings:

Child:

 <many-to-one name="parent" class="ParentClass" column="parentID" cascade="all"/>

Parent:

<bag name="DataList" table="ChildTable" lazy="false" inverse="true" cascade="all-delete-orphan">
      <key column="parentID" />
      <one-to-many class="ChildClass" />
    </bag>

Basically, Is this something nHibernate can do?

Answer 1

I can’t see your parent mapping, but I’d wager if you have inverse = true and cascading turned on there for a set of child objects, and you allow nulls in the parentID column of your child object, when the parent got around to saving it would update the child object properly.