Checking if entity exist

michael.p · **Joined:** Thu May 12, 2005 1:31 pm **Posts:** 4

Is it possible to check if given entity (class mapped with some 'entity-name') exist? I wasn't able to find method for this task.

M.P.

borak · **Posted:** Fri May 27, 2005 4:34 am

query it!

alesj · **Posted:** Fri May 27, 2005 7:14 am

boolean exists = session.get(clazz, id) != null;

michael.p · **Joined:** Thu May 12, 2005 1:31 pm **Posts:** 4

Query it? How?

session.createQuery("from SomeEntity").list() throws exception, if SomeEntity does not exist. I don't like this way.

I can't use session.get() either, because I can't imply that particular id is valid.

Entity name is passed to servlet as a request parameter. Servlet calls Dao layer and obtain list of objects from table mapped to this entity. But if entity don't exist, exception is throwed...

jjdunne · **Joined:** Thu Feb 17, 2005 4:20 pm **Posts:** 29

does this do it?

Code:

SessionImplementor session = (SessionImplementor) HibernateSessionManager.getSession();
final PersistenceContext persistenceContext = session.getPersistenceContext();
EntityKey key = new EntityKey( entity.getId(), session.getEntityPersister( null, entity) , session.getEntityMode()  );

if ( persistenceContext.containsEntity( key ) ) {
  //entity exits
} else {
  //entity does not exist
} 

michael.p · **Joined:** Thu May 12, 2005 1:31 pm **Posts:** 4

uhm.. no ;)

You are talking about entity = loaded from database object. I'm thinking about class mapped with "entity-name" property (Hibernate 3.x feature).

Anyway, I find it:

Session session = ...
boolean exist = session.getSessionFactory().getClassMetadata("some_mapped_entity") != null;