When I merge entity Foo, got the following exception: trying to cast the entity to Long type, how could this be possible?
Can someone give me some help on what might be the cause? Thanks!

Caused by: java.lang.ClassCastException: xyz.Foo cannot be cast to java.lang.Long
20:28:20,493 ERROR [STDERR] at org.hibernate.type.LongType.set(LongType.java:42)
20:28:20,493 ERROR [STDERR] at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:83)
20:28:20,494 ERROR [STDERR] at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:65)
20:28:20,494 ERROR [STDERR] at org.hibernate.loader.Loader.bindPositionalParameters(Loader.java:1513)
20:28:20,494 ERROR [STDERR] at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1575)
20:28:20,494 ERROR [STDERR] at org.hibernate.loader.Loader.doQuery(Loader.java:661)
20:28:20,494 ERROR [STDERR] at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
20:28:20,494 ERROR [STDERR] at org.hibernate.loader.Loader.loadEntity(Loader.java:1784)
20:28:20,494 ERROR [STDERR] at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:48)
20:28:20,494 ERROR [STDERR] at org.hibernate.loader.entity.EntityLoader.loadByUniqueKey(EntityLoader.java:85)
20:28:20,494 ERROR [STDERR] at org.hibernate.persister.entity.AbstractEntityPersister.loadByUniqueKey(AbstractEntityPersister.java:1581)
20:28:20,494 ERROR [STDERR] at org.hibernate.type.EntityType.loadByUniqueKey(EntityType.java:365)
20:28:20,494 ERROR [STDERR] at org.hibernate.type.EntityType.resolve(EntityType.java:306)
20:28:20,494 ERROR [STDERR] at org.hibernate.type.EntityType.replace(EntityType.java:207)
20:28:20,494 ERROR [STDERR] at org.hibernate.type.TypeFactory.replace(TypeFactory.java:437)
20:28:20,494 ERROR [STDERR] at org.hibernate.event.def.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:340)
20:28:20,494 ERROR [STDERR] at org.hibernate.event.def.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:267)
20:28:20,495 ERROR [STDERR] at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:120)
20:28:20,495 ERROR [STDERR] at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:53)
20:28:20,495 ERROR [STDERR] at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:677)
20:28:20,495 ERROR [STDERR] at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:661)
20:28:20,495 ERROR [STDERR] at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:665)
20:28:20,495 ERROR [STDERR] at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:227)
20:28:20,495 ERROR [STDERR] at org.jboss.ejb3.entity.TransactionScopedEntityManager.merge(TransactionScopedEntityManager.java:181)

I am using JBoss 4.0.5GA. How/where to get the Hibernat source code for the JBoss version? I need to debug it.

The class Foo has a number of assocations that is only used for delete cascade.

@OneToMany(fetch=FetchType.LAZY, mappedBy="foo", cascade=CascadeType.REMOVE)
public List<Bar> getBarList() {
return BarList;
}

@OneToMany(fetch=FetchType.LAZY, mappedBy="foo", cascade=CascadeType.REMOVE)
public List<Baz> getBarList() {
return BazList;
}

@OneToOne(fetch=FetchType.LAZY, mappedBy="foo", cascade=CascadeType.REMOVE)
public Bax getBax() {
return Bax;
}


If I remove these associations, em.merge(foo) works.
I could not figure out why. Any workaround?
Thanks!

This is an old bug that has been fixed http://opensource.atlassian.com/projects/hibernate/browse/EJB-229
Update to the latest version and you should be fine