hibernate - How to retrieve the audited revision of relations?

Question

Here is my use case

I have two entities : Personn and Email (a @OneToMany relation). Both of them are audited.

First I create a new Personn, with an Email (=> Both of them have a revision 1), then I modify the Email (=> The Email has a revision 2, but Personn has only a revision 1)

In the web application the end-user has only one view to show the Personn's attributs and also his Emails attributs. In this view I want to show all existing revisions for this Personn. But when I query the audit system, it doesn't show me revision 2 as the Personn has not been modified.

I understand the technical problem, but in the end-user point of view, he wants to see a revision 2 because he modified the personn's email ! He doesn't know (and doesn't have to know) that we deciced to divide these information into 2 Java objects. Of course this problem is not only for Personn-Email relation (I've got a lot of relation between Personn and other objects which are shown in the same view - Adress, Job, Site, Card, and many more)

I thought about 2 solutions:

1- Querying all relations to know if a Revision exist (but I suppose it will generate a big request or multiple requests - I've got a lot of relations).

2- Setting "hibernate.listeners.envers.autoRegister" to false, writing my own EnversIntegrator and event implementations. In event implementations (which override default Envers implementations), I will create a ModWorkUnit for Personn when Email's attributs have been modified (it will not been hard coded of course: perharps a custom annotation like @AuditedPropagation on the personn field). The flaw of this solution is to create a lot a row for Personn even if it was not modified.

What do you think about these solutions ? Do you know a better way to solve that kind of use-case ?

Thanks for your advices.

Answer 1

I tried to implement the second solution:

1. First my integrator which adds a new post update listener (RevisionOnCollectionPostUpdateEventListenerImpl)

   public class RevisionOnCollectionUpdateIntegrator implements Integrator {
   private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class, RevisionOnCollectionUpdateIntegrator.class.getName());
   
   public static final String REGISTER_ON_UPDATE = "org.hibernate.envers.revision_on_collection_update";
   
   @Override
   public void integrate(Configuration configuration, SessionFactoryImplementor sessionFactory, SessionFactoryServiceRegistry serviceRegistry) {
   
       final boolean autoRegister = ConfigurationHelper.getBoolean(REGISTER_ON_UPDATE, configuration.getProperties(), true);
       if (!autoRegister) {
           LOG.debug("Skipping 'revision_on_collection_update' listener auto registration");
           return;
       }
   
       EventListenerRegistry listenerRegistry = serviceRegistry.getService(EventListenerRegistry.class);
       listenerRegistry.addDuplicationStrategy(EnversListenerDuplicationStrategy.INSTANCE);
   
       final AuditConfiguration enversConfiguration = AuditConfiguration.getFor(configuration, serviceRegistry.getService(ClassLoaderService.class));
       if (enversConfiguration.getEntCfg().hasAuditedEntities()) {
           listenerRegistry.appendListeners(EventType.POST_UPDATE, new RevisionOnCollectionPostUpdateEventListenerImpl(enversConfiguration));
       }
   }
   

2. And then the post update listener (which extends):

   public class RevisionOnCollectionPostUpdateEventListenerImpl extends EnversPostUpdateEventListenerImpl {
   protected final void generateBidirectionalWorkUnits(AuditProcess auditProcess, EntityPersister entityPersister, String entityName, Object[] newState,
           Object[] oldState, SessionImplementor session) {
       // Checking if this is enabled in configuration ...
       if (!getAuditConfiguration().getGlobalCfg().isGenerateRevisionsForCollections()) {
           return;
       }
   
       // Checks every property of the entity, if it is an "owned" to-one relation to another entity.
       // If the value of that property changed, and the relation is bi-directional, a new revision
       // for the related entity is generated.
       String[] propertyNames = entityPersister.getPropertyNames();
   
       for (int i = 0; i < propertyNames.length; i++) {
           String propertyName = propertyNames[i];
           RelationDescription relDesc = getAuditConfiguration().getEntCfg().getRelationDescription(entityName, propertyName);
           if (relDesc != null && relDesc.isBidirectional() && relDesc.getRelationType() == RelationType.TO_ONE && relDesc.isInsertable()) {
               // Checking for changes
               Object oldValue = oldState == null ? null : oldState[i];
               Object newValue = newState == null ? null : newState[i];
   
                       // Here is the magic part !!!!!!!!!
                       // The super class verify if old and new value (of the owner value) are equals or not
                       // If different (add or delete) then an audit entry is also added for the owned entity
                       // When commented, an audit row for the owned entity is added when a related entity is updated
           //  if (!Tools.entitiesEqual(session, relDesc.getToEntityName(), oldValue, newValue)) {
                   // We have to generate changes both in the old collection (size decreses) and new collection
                   // (size increases).
                   if (newValue != null) {
                       addCollectionChangeWorkUnit(auditProcess, session, entityName, relDesc, newValue);
                   }
   
                   if (oldValue != null) {
                       addCollectionChangeWorkUnit(auditProcess, session, entityName, relDesc, oldValue);
                   }
           //  }
           }
       }
   }
   

It seems to work but I have to test a little bit more.