Hibernate: org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session

问题

I wonder why this exception happens although it's assured by Hibernate get/query methods to retrieve objects that are already available inside the Hibernate session in case those objects are required repeatedly:

org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [x.y.z.MyObject#130062]
    at org.hibernate.engine.StatefulPersistenceContext.checkUniqueness(StatefulPersistenceContext.java:638)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performUpdate(DefaultSaveOrUpdateEventListener.java:305)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsDetached(DefaultSaveOrUpdateEventListener.java:246)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:112)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
    at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:685)
    at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:677)
    at org.hibernate.engine.CascadingAction$5.cascade(CascadingAction.java:252)
    at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:392)
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:335)
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204)
    at org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:425)
    at org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:362)
    at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:338)
    at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204)
    at org.hibernate.engine.Cascade.cascade(Cascade.java:161)
    at org.hibernate.engine.Cascade.cascade(Cascade.java:127)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.cascadeOnUpdate(DefaultSaveOrUpdateEventListener.java:376)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performUpdate(DefaultSaveOrUpdateEventListener.java:350)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsDetached(DefaultSaveOrUpdateEventListener.java:246)
    at org.hibernate.event.def.DefaultUpdateEventListener.performSaveOrUpdate(DefaultUpdateEventListener.java:57)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
    at org.hibernate.impl.SessionImpl.fireUpdate(SessionImpl.java:742)
    at org.hibernate.impl.SessionImpl.update(SessionImpl.java:730)
    at org.hibernate.impl.SessionImpl.update(SessionImpl.java:722)

回答1:

After some debugging I found out that I didn't stop cascading propagation of the update inside a self-referring model:

type1 --> type2 --> type3 --> collection(type1)

So all that needed to be done was to stop cascading with cascade="none" :

<set name="type1collection" ... cascade="none">
...
</set>

That means, a different object with the same identifier value was already associated with the session was hidden inside the self-referring children. The extra update of these children is unnecessary, so no cascading is correct.

来源：https://stackoverflow.com/questions/15005914/hibernate-org-hibernate-nonuniqueobjectexception-a-different-object-with-the-s

标签

java

hibernate

hibernate-mapping