Hi,

I'm trying to develop a custom type in hibernate to hold i18n fields. For that purpouse, I have created a custom Hibernate UserType.The problem is that whenever I need to save my entity, I also need to perform some queries inside the nullSafeSet() method. This works pretty good if all I do is :


but when creating a straight new entity and calling entityManager.persist() it returns the following error:


To create the queries inside the nullSafeSet method, I inject the Seam EntityManager component, which is basically a proxy to the entityManager. It does work when merging, not when persisting. The id field of my entity has Auto Generation.

Can someone bring some light into this? If I remove every entityManager query from my nullSafeSet() method it works, but I can't afford that.

Thank you in advance, and if you need more information, please just ask me.

I have not used user-types myself, but have some experience with the Interceptor interface. In this interface it is clearly stated that it is not allowed to use the current session or trigger lazy initialization of proxies or collections. I guess the reason is to not mess up the internal state of the session or to cause infinite loops, etc. I think the same restrictions may apply to user-types and probably for all other code that can be executed "inside" the session.

In some cases I also had to execute queries inside the Interceptor code. The way I solved it was to create a stateless session using the same connection as the primary session and then used this temporary session for executing queries. Something like this:



I guess it would work to use a second regular session as well. Unfortunately the session.connection() method has been deprecated and there is yet no replacement for this scenario. I could have implemented this with the Work interface and plain SQL but I prefer HQL...

Hope this may be some help for you.

Hi nordborg, thank you for your answer. The strange thing here is that if I'm merging an object (the object is managed) and not persisting it, everything works just fine. I also discovered that if I set the flushMode to COMMIT, I can use my entityManager to call the queries but the preparedStatement that I receive in the nullSafeSet method is already closed, so I get another error... :( Does this make any sense to you?

Also inside the nullSafeSet() method I don't have any session, just a PreparedStatement... I'm kind of lost here really.

Thank you very much for your reply.

Well... I don't know the internals well enough to say if it makes sense or not. I guess you will see all kinds of strange behavior depending on the circumstances. For example, if you are using FlushMode.AUTO a query may trigger a flush and if your user-type code is invoked due to a flush in the first place there is likely to be some kind of clash.



Isn't an entity manager "just a wrapper" around a session? You may have to dig a bit (and cast) but I think it should be possible to get the underlying session somehow. I have not used Seam though so I don't know for sure...

In any case... the PreparedStatment.getConnection() object should get you a connection and then it should be possible to create a Session with SessionFactory.openSession(Connection). I also came to think about that the reason that I need the connection from the main session is that I use the Interceptor to insert data to a log table. With this information it is possible to check when a specific entity was modified and by who. But I don't want to log anything if the main transaction fails and by using the same underlying connection a rollback will undo the log inserts as well as any other modifications. If you just need to query it may just as well work to open a second session using a new connection.