Bi-directional many-to-many mapping question

[Saathvik Reddy]

Hi,

I have an many-to-many relationship mapped with annotations
as below:

    
@Entity
Class User {

// ...some
attributes
private Set<UserGroup> userGroups;

@OneToMany(fetch = FetchType.EAGER, mappedBy = "User",
cascade=CascadeType.ALL)
@org.hibernate.annotations.Cascade(value =
org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
public Set
getUserGroups() { return this.userGroups; }
// getter/setter(s)

}

@Entity
Class Group {
// ...some
attributes
private Set<UserGroup> userGroups;

@OneToMany(fetch = FetchType.EAGER, mappedBy = "Group",
cascade=CascadeType.ALL)
@org.hibernate.annotations.Cascade(value =
org.hibernate.annotations.CascadeType.DELETE_ORPHAN)
public Set
getUserGroups() { return this.userGroups; }
// getter/setter(s)
}

@Entity
Class UserGroup {
// ...some
attributes
private User user;
private Group group;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name =
"userId", nullable = false, insertable = false, updatable =
false)
public User getUser() { return this.user }

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name =
"groupId", nullable = false, insertable = false, updatable =
false)
public Group getGroup() { return this.group }

}

I am updating the UserGroup by doing:

user.getUserGroups().remove(userGroup1);
entityManager.merge(user);

I am getting this exception:

Caused by: org.hibernate.ObjectDeletedException: deleted entity
passed to persist: [UserGroup#<null>]
        at
org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:90)
        at
org.hibernate.impl.SessionImpl.firePersistOnFlush(SessionImpl.java:644)
        at
org.hibernate.impl.SessionImpl.persistOnFlush(SessionImpl.java:636)
        at
org.hibernate.engine.CascadingAction$9.cascade(CascadingAction.java:323)
        at
org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:268)
        at
org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:216)
        at
org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:169)
        at
org.hibernate.engine.Cascade.cascadeCollectionElements(Cascade.java:296)
        at
org.hibernate.engine.Cascade.cascadeCollection(Cascade.java:242)
        at
org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:219)
        at
org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:169)
        at
org.hibernate.engine.Cascade.cascade(Cascade.java:130)
        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.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:26)
        at
org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
        at
org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338)
        at
org.hibernate.transaction.JTATransaction.commit(JTATransaction.java:135)
        at
org.hibernate.ejb.TransactionImpl.commit(TransactionImpl.java:54)
        at
org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:456)

If i remove cascade=CascadeType.ALL from Group entity i
don't get any exception but i want to keep cascade in Group entity.
Is there anything i need to do to get rid of this exception or I should
remove cascade in Group entity?

Thanks,

[Saathvik Reddy]

Could anyone please let me know

[Cameron Wallace McKenzie]

[UserGroup#<null>]

I think this means the primary key of the object you are trying to delete is null. Can you verify this by doing some logging? So, if the primary key is null and you ask Hibernate to delete it, it won't know what row in the underlying database to delete.

-Cameron McKenzie