How can I create a hibernate collection that will be re-read every time I request it?

Question

I have an entity that has a state table associated with it. The state table is managed by another process, and contains a list of objects that my business logic must process. I would like to get a new snapshot of the state table each time I reload the entity. How can I ensure that no part of Hibernate or its support libraries ever caches any of the values of this table? Basically, I want to get a new view of the collection every time I call getMyStateValues ().

Answer 1

Most of the point of Hibernate is to prevent that from happening and return a consistent view of an entity's state in the scope of a given transaction. So either reload the whole entity, in different transactions every time. Or, if you need to reload the state table during a business transaction, load only the state table by the parent entity's id in a separate Hibernate session.

Answer 2

You can create a method in your entity that queries the database and return the collection. getXYXReload(). It´s not a very nice design decision, thought.

Answer 3

You can use Hibernate's CacheMode. It allows you to instruct a hibernate session on how to interact with the cache. You can get access to the underlying session with:

@PersistenceContext EntityManager manager;
...
org.hibernate.Session session = (Session)manager.getDelegate();

Unfortunately, this technique applies to the whole session, and not specifically to an entity.