JPA relation changes not updated in PreUpdate callback - spring

Question

In my current project I have an entity which can be published to other systems. For keeping track on the publications the entity has a relation called "publications". I am using Eclipselink.
This entity bean also has a "PreUpdate" annotated method.
In order to be able to keep the other systems data up to date, I created an Aspect that is executed around the call to the PreUpdate method. Depending on which properties have changed, I need to remove some of the publications. Everything is working absolutely fine.
The problem I am having is that the portal-publishing component correctly sends delete commands and removes the publication from the entities "publications" list. I can even see in the changeset that JPA has noticed the "publications" property to have changed. After the transaction is flushed, the cached entity correctly doesn't have the deleted publications anymore. Unfortunately the database still does and when the system is restarted or the Entity is loaded from the DB again, the publication metadata is there again.
I tried allmost everything. I even managed to get the deleted instances from the JPA ChangeSet in the Aspect and tried to use the entityManager to manually delete them, but nothing actually worked. I seem to be unable to delete these relational entities. Currently I am thinking about using JDBC to delete them, but this would only be my last measure.
#Transactional
#Around("execution(* de.cware.services.truck.model.Truck.jpaPreUpdate(..))")
public Object truckPreUpdate(final ProceedingJoinPoint pjp) throws Throwable {
if (alreadyExecutingMarker.get() != Boolean.TRUE) {
alreadyExecutingMarker.set(Boolean.TRUE);
final Truck truck = (Truck) pjp.getTarget();
final JpaEntityManager jpaEntityManager = (JpaEntityManager) entityManager.getDelegate();
final UnitOfWorkChangeSet changeSet = jpaEntityManager.getUnitOfWork().getCurrentChanges();
final ObjectChangeSet objectChangeSet = changeSet.getObjectChangeSetForClone(truck);
if (log.isDebugEnabled()) {
log.debug("--------------------- Truck pre update check (" + truck.getId() + ") ---------------------");
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////
// If the truck date has changed, revoke all publication copies.
////////////////////////////////////////////////////////////////////////////////////////////////////////////
final ChangeRecord truckFreeDate = objectChangeSet.getChangesForAttributeNamed("lkwFreiDatum");
if (truckFreeDate != null) {
if (log.isDebugEnabled()) {
log.debug("The date 'truckFreeDate' of truck with id '" + truck.getId() + "' has changed. " +
"Revoking all publications that are not marked as main applications");
}
for (final String portal : truck.getPublishedPortals()) {
if (log.isDebugEnabled()) {
log.debug("- Revoking publications of copies to portal: " + portal);
}
portalService.deleteCopies(truck, portal);
// Get any deleted portal references and use the entityManager to finally delete them.
changeSet = jpaEntityManager.getUnitOfWork().getCurrentChanges();
objectChangeSet = changeSet.getObjectChangeSetForClone(truck);
final ChangeRecord publicationChanges = objectChangeSet.getChangesForAttributeNamed("publications");
if (publicationChanges != null) {
if (publicationChanges instanceof CollectionChangeRecord) {
final CollectionChangeRecord collectionChanges =
(CollectionChangeRecord) publicationChanges;
#SuppressWarnings("unchecked")
final Collection<ObjectChangeSet> removedPublications =
(Collection<ObjectChangeSet>)
collectionChanges.getRemoveObjectList().values();
for (final ObjectChangeSet removedPublication : removedPublications) {
final TruckPublication publication = (TruckPublication) ((org.eclipse.persistence.internal.sessions.ObjectChangeSet) removedPublication).getUnitOfWorkClone();
entityManager.remove(publication);
}
}
}
}
}
}
}
Chris

Answer 1

The issue is that PreUpdate is raised during the commit process, when the set of changes have already been computed, and the set of objects to delete have already been computed.
Ideally you would perform something like this in your application logic, not through a persistence event.
You could try executing a DeleteObjectQuery directly from your event (instead of using em.remove()), this may work, but in general it would be better to perform this logic in your application.
jpaEntityManager.getUnitOfWork().deleteObject(object);
Also note that getCurrentChanges() computes the changes, in a PreUpdate event the changes are already computed, so you should be able to use getUnitOfWorkChangeSet().

Answer 2

The only solution I found was to create a new Method for performing the delete and forcing JPA to create a new Transaction. As by this I am losing the changeSet, I had to manually find out which publications were deleted. I then simply call that helper method and the publications are correctly deleted, but I find this solution extremely ugly.
#Transactional
#Around("execution(* de.cware.services.truck.model.Truck.jpaPreUpdate(..))")
public Object truckPreUpdate(final ProceedingJoinPoint pjp) throws Throwable {
if (alreadyExecutingMarker.get() != Boolean.TRUE) {
alreadyExecutingMarker.set(Boolean.TRUE);
final Truck truck = (Truck) pjp.getTarget();
final JpaEntityManager jpaEntityManager = (JpaEntityManager) entityManager.getDelegate();
final UnitOfWorkChangeSet changeSet = jpaEntityManager.getUnitOfWork().getCurrentChanges();
final ObjectChangeSet objectChangeSet = changeSet.getObjectChangeSetForClone(truck);
if (log.isDebugEnabled()) {
log.debug("--------------------- Truck pre update check (" + truck.getId() + ") ---------------------");
}
////////////////////////////////////////////////////////////////////////////////////////////////////////////
// If the truck date has changed, revoke all publication copies.
////////////////////////////////////////////////////////////////////////////////////////////////////////////
final ChangeRecord truckFreeDate = objectChangeSet.getChangesForAttributeNamed("lkwFreiDatum");
if (truckFreeDate != null) {
if (log.isDebugEnabled()) {
log.debug("The date 'truckFreeDate' of truck with id '" + truck.getId() + "' has changed. " +
"Revoking all publications that are not marked as main applications");
}
removeCopyPublications(truck);
}
}
#Transactional(propagation = Propagation.REQUIRES_NEW)
protected void removeCopyPublications(Truck truck) {
// Delete all not-main-publications.
for (final String portal : truck.getPublishedPortals()) {
if (log.isDebugEnabled()) {
log.debug("- Revoking publications of copies to portal: " + portal);
}
final Map<Integer, TruckPublication> oldPublications = new HashMap<Integer, TruckPublication>();
for(final TruckPublication publication : truck.getPublications(portal)) {
oldPublications.put(publication.getId(), publication);
}
portalService.deleteCopies(truck, portal);
for(final TruckPublication publication : truck.getPublications(portal)) {
oldPublications.remove(publication.getId());
}
for (TruckPublication removedPublication : oldPublications.values()) {
if(!entityManager.contains(removedPublication)) {
removedPublication = entityManager.merge(removedPublication);
}
entityManager.remove(removedPublication);
entityManager.flush();
}
}
}
Why doesn't my first version work?

Answer 3

I had a similar problem, I have a class and its children, when I remove the children from the parent they were deleted from the DB, then I attached new children using merge on the class Parent (CascadeType.ALL) using JPA/EclipseLink, then the children didn't create on the DB but in the persistency Motor (JPA). I fix this doing the following:
1- I set shared-cache-mode to NONE in the persistence.xml file
2- When I remove the children, I executed inmediatly this:
public void remove(T entity) {
getEntityManager().remove(getEntityManager().merge(entity));
getEntityManager().getEntityManagerFactory().getCache().evictAll();
}
And that's all. I hope this would help anyone else.
CHECK REFERENCE
http://wiki.eclipse.org/EclipseLink/Examples/JPA/Caching