The problem:
I'm using ODMG transactions, and I normally set foreign-key ID fields
directly rather than set reference-object fields. I ran into problems
when I did the following sequence of events, working with an ODMG
database 'db' and a PersistenceBroker 'broker':
A a = new A();
db.makePersistent(a);
B b = new B();
b.setAId(a.getId());
broker.retrieveAllReferences(b); // so that B's reference to
// A gets updated from the
// foreign key field I just set
db.makePersistent(b);
In the last step, I get:
java.lang.NullPointerException
at
org.apache.ojb.odmg.TransactionImpl.assertFkAssignment(TransactionImpl.j
ava:811)
at
org.apache.ojb.odmg.TransactionImpl.assignReferenceFKs(TransactionImpl.j
ava:852)
at
org.apache.ojb.odmg.TransactionImpl.lock(TransactionImpl.java:259)
at
org.apache.ojb.odmg.DatabaseImpl.makePersistent(DatabaseImpl.java:409)
because at the time I make B persistent its reference to A is a proxy
that has not yet been materialized, and cannot be materialized via
getRealSubject() - it is not yet known to the persistence broker, only
to the ObjectEnvelopeTable in the current transaction.
My solution:
I added code to TransactionImpl.assertFkAssignment() that tries to fetch
the proxy via the ObjectEnvelopeTable in case real materialization
fails:
...
else if (ref instanceof Proxy)
{
IndirectionHandler ih = (IndirectionHandler)
Proxy.getInvocationHandler(ref);
refInstance = ih.getRealSubject();
/* Begin patch */
if (refInstance == null) {
refInstance =
objectEnvelopeTable.getByIdentity(ih.getIdentity()).getObject();
}
/* End patch */
}
...
Regards,
Scott Howlett
----------------
Scott Howlett
PDK Solutions Group
978-262-6692 (office)
617-721-7198 (mobile)
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