Hi,

I was having a problem persisting a new child object using Hibernate 3.0.5 and MySql.

I have two object TrainingTask and TrainingTaskRevision. A TrainingTask has many revisions.

TrainingTask had a set of revisions and the revision had a one-many relationship back to the task.

I mapped the TrainingTask with the inverse="true" attribute.

The mappings were fine because I could retrieve the objects. I just couldn't persist a new one by just saving the parent (TrainingTask).

My code was as follows:

// create the revision
TrainingTaskRevision revision = new TrainingTaskRevision();
// populate it's properties

// set the relationships
revision.setTask(task);
task.getRevisions().add(revision);

taskDao.save(task);

That didn't work.

All I had to do to fix this issue was add:

taskDao.save(revision);
taskDao.save(task);

***NOTE: This is a legacy database without any foreign keys between the two tables.

Real question: Does hibernate need/use the foreign keys in order to persist a child?

Here are my mapping tags:

** NOTE above classes were shortened.

<!-- Mapping inside Task object -->
<set name="taskRevisions" inverse="true" cascade="all-delete-orphan" lazy="true">
<key column="task_id" />
<one-to-many class="com.qslabs.skills.impl.TrainingTaskRevisionDb" />
</set>


<!-- mapping inside TaskRevision object -->
<many-to-one
name="trainingTask"
column="task_id"
not-null="true"
lazy="true"
class="com.qslabs.skills.impl.TrainingTaskDb" />