Problem creating non-persistent Child Objects

Question

I have the need to create a non persistable child object in the
jdoPreStore of a parent object. I then perform some tests on the parent
to determine if the child object needs to be persisted or not. If I leave
the child non persistent it still writes to the database.
I was performing the follwoing piece of code
Class Parent {
// The relationship is a 0 to many
public Child createChild() {
Child child = .....//create non persistent object
child.setParent(this);
getChild().add(child);
It appears that if I remove the getChild().add(child). It does not
persist (as desired).
Is this correct behaviour?? I dont think that it should be, but if it is
then I have a further problem.
If that child object inherits from another object and you remove the
getChild().add(child) kodo outputs an invalid object to the database. It
doesnt insert a row to the child table. But it inserts a row to the
childs inherited object table. This is now an invalid object and will
fail upon loading.
Any help on this would be appreciated.
Thanks
Luke.

Answer 1

JDO has something called persistence by reachability. This means that
objects do not have to explicitly be marked as to be persistent as JDO
will traverse the object graph to ensure that all nodes are persistent.
I think you are seeing this behavior combined with another side
behavior: Kodo requires that both sides of a relation be set.
Basically, keep your objects in synch (set both sides of the relation).
And if you want to hold onto a reference to non-persistent object
before you decide what to do with it, add a transient field or a field
marked "persistence-modifier="none"" in your metadata and then process
those transient fields in jdoPreStore ().
i.e.
if (//businessLogic is true)
persistentField = transientField;
Luke wrote:
I have the need to create a non persistable child object in the
jdoPreStore of a parent object. I then perform some tests on the parent
to determine if the child object needs to be persisted or not. If I leave
the child non persistent it still writes to the database.
I was performing the follwoing piece of code
Class Parent {
// The relationship is a 0 to many
public Child createChild() {
Child child = .....//create non persistent object
child.setParent(this);
getChild().add(child);
It appears that if I remove the getChild().add(child). It does not
persist (as desired).
Is this correct behaviour?? I dont think that it should be, but if it is
then I have a further problem.
If that child object inherits from another object and you remove the
getChild().add(child) kodo outputs an invalid object to the database. It
doesnt insert a row to the child table. But it inserts a row to the
childs inherited object table. This is now an invalid object and will
fail upon loading.
Any help on this would be appreciated.
Thanks
Luke.
Steve Kim
[email protected]
SolarMetric Inc.
http://www.solarmetric.com