[jboss-user] [JBoss Seam] - EntityHome silently discards updates after errors

[cja987]

In the framework, I'm trying to enforce optimistic locking and a unique constraint on the "name" attribute.  For optimistic locking, there's not a lot I can do except kick them out (they can always open a new window and use their back button to copy their changes and merge them in).  For name conflicts, I thought to add a message and let them try something else.

Here's the code:


  | 	@End @Transactional @Override
  | 	public String update() {
  | 		getInstance().setUpdatedOn(new Date());
  | 		try {
  | 			return super.update();
  | 		} catch (OptimisticLockException e) {
  | 			facesMessages.add("#{messages.staleEditRule}");
  | 			return "aborted";
  | 		} catch (EntityExistsException e) {
  | 			facesMessages.add("name", "#{messages.errNameExists}");
  | 			return null;
  | 		} catch (RuntimeException e) {
  | 			facesMessages.add(e.toString());
  | 			return null;
  | 		}
  | 	}
  | 

Only problem is, this appears to work -- you correct the name, hit update, your changes appear to take, you're back in the view screen -- but when you next view the entity you edited, you find your changes never actually took.

I think I understand why this is happening -- the session is no longer valid after an exception -- but there's no indication even in log messages that this has happened, and the update was just silently dropped.

So I have two questions: 

1) Is the lost update detectable somehow?  I feel like EntityManager should have screamed at me for trying to update again after the exception, but it gave nary a peep.  

2) How do I gracefully recover from errors on update and reset the entityManager so further updates can succeed?  Should I make the unique constraint a validator instead?  Enforcing unique constraints must be a FAQ for Hibernate, but I haven't found an answer yet.



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