ManyToOne org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing

[kleinerroemer]

Hey Guys!

This is more a hibernate problem than a seam problem but I hope you have some ideas!

I've got to classes referencing each other like this:

Class A:

       @Id 
        @GeneratedValue
        @Basic
        protected long id;

        @Basic
        @Column(unique=true)
        protected String extern_id;

        @ManyToOne
        @Nullable
        protected B b;

Class B:

        @Id 
        @GeneratedValue
        @Basic
        protected long id;

        @Basic
        @Column(unique=true)
        protected String extern_id;

        @OneToMany
        protected List<A> a;

In my Import script (import-dev.sql) im Inserting some values for a:

insert into A (extern_id) values ('8812948')
insert into A (extern_id) values ('1254123')

If I now try to load A with this query:

em.createQuery( "from A a where a.extern_id = :eid" ).setParameter( "eid", eid ).getSingleResult();

by extern id it, works fine for the first one, but not for the second one. If I remove the second one, the error gets thrown while loading the first one.
If I try to load A by its' natural id, it works fine.

There is absolutely no difference between the two entries.

It is also not working, if I set b id for a!

I won't provide the full stack trace here, since it is very long, and not telling anything intresting (at least from my point of view).

I hope you have some ideas!

Greets

[kleinerroemer]

that the error looks like:

Caused by: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: A.b -> B
        at org.hibernate.engine.CascadingAction$9.noCascade(CascadingAction.java:353)
        at org.hibernate.engine.Cascade.cascade(Cascade.java:139)
        at org.hibernate.event.def.AbstractFlushingEventListener.cascadeOnFlush(AbstractFlushingEventListener.java:131)
        at org.hibernate.event.def.AbstractFlushingEventListener.prepareEntityFlushes(AbstractFlushingEventListener.java:122)
        at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:65)
        at org.hibernate.event.def.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:35)
        at org.hibernate.impl.SessionImpl.autoFlushIfRequired(SessionImpl.java:969)
        at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1114)
        at org.hibernate.impl.QueryImpl.list(QueryImpl.java:79)
        at org.hibernate.ejb.QueryImpl.getSingleResult(QueryImpl.java:80)