How to autogenerate created or modified timestamp field?

Question

My entity class:

@Entity
@Table(name = \"user\")
public class User implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
           


        

Answer 1

We do this with a PreInsertEventListener and a PreUpdateEventListener :

public class TracabilityListener implements PreInsertEventListener,PreUpdateEventListener {
    private void setPropertyState(Object[] propertyStates, String[] propertyNames,String propertyName,Object propertyState) {
        for(int i=0;i<propertyNames.length;i++) {
            if (propertyName.equals(propertyNames[i])) {
                propertyStates[i]=propertyState;
                return;
            }
        }
    }
    private void onInsert(Object entity,Object[] state, String[] propertyNames) {
        if (entity instanceof DomainObject) {
            DomainObject domainObject = (DomainObject) entity;
            Date date=new Date();
            domainObject.setDateCreation(date);
            setPropertyState(state, propertyNames, "dateCreation", date);
            domainObject.setDateModification(date);
            setPropertyState(state, propertyNames, "dateModification", date);
        }
    }

    private void onUpdate(Object entity,Object[] state, String[] propertyNames) {
        if (entity instanceof DomainObject) {
            DomainObject domainObject = (DomainObject) entity;
            Date date=new Date();
            setPropertyState(state, propertyNames, "dateCreation", domainObject.getDateCreation());
            domainObject.setDateModification(date);
            setPropertyState(state, propertyNames, "dateModification", date);
        }
    }

    @Override
    public boolean onPreInsert(PreInsertEvent event) {
        onInsert(event.getEntity(), event.getState(), event.getPersister().getPropertyNames());
        return false;
    }

    @Override
    public boolean onPreUpdate(PreUpdateEvent event) {
        onUpdate(event.getEntity(), event.getState(), event.getPersister().getPropertyNames());
        return false;
    }
}

But if you want your properties to be timestamps, then they should be annotated with

@Temporal(TemporalType.TIMESTAMP)

Answer 2

Recently I encountered the same problem and the JPA-Annotations @PrePersist and @PreUpdate won't work when using the hibernate sessionFactory.

A simple way which worked for me with Hibernate 5 is to declare the field as @Version, which will properly update the timestamp/localDateTime of the entity each time you update the database instance.