How to update a Timestamp property when only some entity fields get modified with JPA and Hibernate

Hibernate ORM
2

You have multiple options:

  1. You can update the createdDate in the setters:

     public void setFirstName(String firstName) {
 	this.firstName = firstName;
 	this.createdDate = new Date();
 }

  2. You can register a FlushEntityEventListener that checks the modified properties, as explained in this article:

     public class EntityUpdateEventListener
 	implements FlushEntityEventListener {
  
 	@Override
 	public void onFlushEntity(FlushEntityEvent event) throws HibernateException {
 		final EntityEntry entry = event.getEntityEntry();
 		final Object entity = event.getEntity();
 		final boolean mightBeDirty = entry.requiresDirtyCheck( entity );
  
 		if(mightBeDirty && entity instanceof RootAware) {
 			RootAware rootAware = (RootAware) entity;
 			if(updated(event)) {
 				Object root = rootAware.root();
 				root.setCreatedDate(new Date());
 			}
 		}
 	}
  
 	private boolean updated(FlushEntityEvent event) {
 		final EntityEntry entry = event.getEntityEntry();
 		final Object entity = event.getEntity();
  
 		int[] dirtyProperties;
 		EntityPersister persister = entry.getPersister();
 		final Object[] values = event.getPropertyValues();
 		SessionImplementor session = event.getSession();
  
 		if ( event.hasDatabaseSnapshot() ) {
 			dirtyProperties = persister.findModified(
 				event.getDatabaseSnapshot(), values, entity, session
 			);
 		}
 		else {
 			dirtyProperties = persister.findDirty(
 				values, entry.getLoadedState(), entity, session
 			);
 		}
  
 		return dirtyProperties != null;
 	}
 }