how to get previouseState without fetching from the db using hibernate interceptor to create audit trail table?

Question

I am trying to create an Audit table that will ends looking something like that :

entity,id,property,oldValue,newValue,user,timestamp

using hibernate EmptyInterceptor I expect that this table will have a lot of IO's . It seems that previouseState at onFlushDirty method is not working as I expected .

how can I get the old value without fetching it from the db as shown here ?

I was trying to follow this post

public class AuditLogInterceptor extends EmptyInterceptor {
    private Set inserts    = new HashSet();
    private Set updates    = new HashSet();
    private Set deletes    = new HashSet();
    private Map oldies     = new HashMap();

    @Override
    public boolean onSave(Object entity,
                          Serializable id,
                          Object[] state,
                          String[] propertyNames,
                          Type[] types)
            throws CallbackException {
        if (entity instanceof Auditable)
            inserts.add((Auditable)entity);
        return false;
    }

    @Override
    public void onDelete(Object entity, Serializable id, Object[] state,
            String[] propertyNames, Type[] types) {
        if (entity instanceof Auditable)
            deletes.add((Auditable)entity);
    }

    @Override
    public boolean onFlushDirty(Object entity,
                                Serializable id,
                                Object[] currentState,
                                Object[] previousState,
                                String[] propertyNames,
                                Type[] types)
            throws CallbackException {
        if (entity instanceof Auditable) {
            try {
                // Use the id and class to get the pre-update state from the database
                Session tempSession =
                    HibernateUtil.getSessionFactory().openSession();
                Auditable old = (Auditable) tempSession.get(entity.getClass(), ((Auditable) entity).getId());
                oldies.put(old.getId(), old);
                updates.add((Auditable)entity);
            } catch (Throwable e) {
                _log.error(e,e);
            }
        }
        return false;
    }

is there a way of getting the get the pre-update state without a round trip to the db ?

Answer 1

An alternative approach is to store the previous state on load.

@Entity
@Table(name='Foo')
class Foo {

    @Transient
    private Foo previousState;

    @PostLoad
    private void setPreviousState(){
        previousState = new Foo();
        //copy the fields
    }

    public Foo getPreviousState(){
        return previousState;
    }

}