Datanucleus JPA Update & Delete operation

I am using Datanucleus as the JPA engine to perform CRUD on an entity in Force.com DB. Insert and Select are working fine, but while updating a new row is getting created and delete does not remove the record at all. I am using following for transaction enforcement

Is there kind of an issue with the proxy object to actual object synchronization after the object has been fetched, modified and then subject to updating.

It seems that as the ORM l开发者_JAVA技巧ayer (datanucleus+force sdk) is unable to match between the altered object and the original one, it is landing up creating new row.

Any help is highly appreciated.

Thanks

It would help if you can post your code. But I am guessing you might be hitting a known difference in behavior between DataNucleus and other ORMs like Hibernate.

Are you doing something like this?

MyEntity ent = new MyEntity();
ent.setId(idFromWebRequest);
ent.setXXX(valueFromWebRequest);
ent = entityManager.merge(ent);

(where the instantiation and setters might be carried out by a data binding mechanism such as Spring MVC). If you do it like this, it will not work with DataNucleus but it will work with Hibernate. For DataNucleus you must instead do:

MyEntity ent = entityManager.find(MyEntity.class, idFromWebRequest);
ent.setXXX(valueFromWebRequest);
ent = entityManager.merge(ent);

I would prefer it worked like Hibernate, but the DataNucleus team believes this is the correct behavior. Maybe they can chime in. I believe it's a matter of when you consider an entity a new entity vs. a detached entity. If your entity instance is detached, then calling merge on it should reattach it and your database row will be updated at transaction commit / flush. If it's a new instance, then the entity manager will always create a new record.

As for your delete issue, I don't know what it could be. Perhaps you can post a code sample? You can find a complete CRUD sample app using the JPA provider here:

https://github.com/forcedotcom/javasample-musiclib