Question

I have found the technique in the answer below very useful for transparently managing the created and updated timestamp for entities:

hard time setting autogenerated time with hibernate JPA annotations

I am wondering if there is something similar for recording the create and update user for the entity?

@PreUpdate
@PrePersist
public void updateAudit() {
    lastModifiedDate = new Date();
    lastModifiedUser = ??;
    if (dateCreated==null) {
      dateCreated = new Date();
      userCreated = ??;
    }
}

While new Date() in the example provides the current time, I am having trouble finding a location in which the user id could be stored (at logon time) which is accessible from a @PrePersist annotated method on an entity.

Injecting a @LoggedInUser with a @Produces method would be ideal but my entities are created by new() rather than by injection so are not managed.

I’m pretty new to this so I hope I’m missing something obvious. Thanks.

[edit] Answer below from prunge led to code (abridged)

@MappedSuperclass
public abstract class BaseEntity implements Serializable, Comparable<BaseEntity> {

    @Version
    private Timestamp updatedTimestamp;

    private static ThreadLocal<Long> threadCurrentUserId = new ThreadLocal<Long>();

    /* Called from entry point like servlet 
    */
    public static void setLoggedInUser(BaseEntity user) {
        if (user!=null) threadCurrentUserId.set(user.getId());
    }

    @PrePersist
    @PreUpdate
    protected void onCreateOrUpdate() {
         //Note we don't have to update updatedTimestamp    since the @Version annotation does it for us
         if(createdTimestamp==null) createdTimestamp = new Timestamp(new Date().getTime());;

         lastUpdatedByUserId = threadCurrentUserId.get();
         if(createdByUserId==null)  createdByUserId = lastUpdatedByUserId;
    }

Answer 1

If it’s a webapp, you could use a ThreadLocal for storing the current user.

• Set the ThreadLocal value in a servlet filter, reading the user from servlet request.
• Read the ThreadLocal value from your JPA entities.
• Clear the value on the trip back through the filter.