JPA Reference with "orphanRemoval"
JPA 2 supports an additional and more aggressive remove cascading mode which can be specified using the orphanRemoval element of the @onetoone and @onetomany annotations:
JPA will keep track of the referencing Objects which need to be removed, when its managed via an PersistentBag:
@OneToMany(..., orphanRemoval = true) private List<Address> addresses = new ArrayList<>(); ... employee = employeeRepository.findById(id); employee.getAddresses().clear()
employee.getAdresses() is a hibernate.PersistenceBag therefore hibernate will track the changes within the collection and propagate those to the underlying database (like delete the addresses which have been referenced by the employee when
orphanRemoval = true)
If we overwrite the Collection, hibernate is unable to tell what has changed and will fail e.g.
employee = employeeRepository.findById(id); employee.setAddresses(findAddresses(employee))
The Error will be something like this when there were Addresses within the Collection
"A collection with cascade=\"all-delete-orphan\" was no longer referenced by the owning entity instance: xxx nested exception is org.hibernate.HibernateException: A collection with cascade=\"all-delete-orphan\" was no longer referenced by the owning entity instance: xxx"