I have a situation where I have two classes, Statement and InProgressStatement that both map to the same table, statement. InProgressStatement extends Statement and adds the context of parsing an electronic statement, but does not add any additional persistent fields. I had to promote InProgressStatement to a persistent class, however, to persist the statement. What I am seeing is that when I have both of these classes registered in my configuration, I get WrongClassExceptions when loading two objects with different types(from different tables) in the same session with the same primary key. If I only register one of the Statement classes, it works fine.

I'd appreciate any clarification.


Hibernate version:

2.1.4

Code between sessionFactory.openSession() and session.close():

Collection results = Statement.findByBank(Bank.findBy(100));//finds bankPK = 100, statementPK = 100 throws Exception

Statement.findByBank:

return session.createCriteria(Statement.class)
.add(Expression.eq("bank", bank))
.list();

Bank.findById:

return (Bank)session.get(Bank.class, id);


Full stack trace of any exception that occurs:

UncheckedDatabaseException: HibernateException detected while executing criteria for findByBank. at Statement.findByBank(Statement.java:623) at StatementTest.testFindByBank(StatementTest.java:265) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)Caused by: net.sf.hibernate.WrongClassException: Object with id: 100 was not of the specified subclass: InProgressStatement (loaded object was of wrong class) at net.sf.hibernate.loader.Loader.instanceAlreadyLoaded(Loader.java:456) at net.sf.hibernate.loader.Loader.getRow(Loader.java:423) at net.sf.hibernate.loader.Loader.doQuery(Loader.java:209) at net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:133) at net.sf.hibernate.loader.Loader.doList(Loader.java:955) at net.sf.hibernate.loader.Loader.list(Loader.java:946) at net.sf.hibernate.loader.CriteriaLoader.list(CriteriaLoader.java:121) at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:3609) at net.sf.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:238) at

Name and version of the database you are using:

I am seeing this on both Oracle and SQLServer

Incorrect. This will happen (in 2.1.6 and prior) when, within a single session, Hibernate is asked to load the same database row twice and map it to two seperate classes. This is true whether you explicitly ask it to load a class instance, or if it needs to load a class instance via a mapped association.

Mapping two different classes to the same database row is a bad idea, in general; and prior to 2.1.7 it won't even work if you try to load that row into more than one class as I mentioned above.

Thanks for the explanation. I can see how that would be a problem. I will upgrade to the latest version and see if that solves my problem.