[jboss-user] [EJB 3.0] - Detached entity passed to persist
Hi!
I receive an error when I try to persist an entity bean. I have a bean (A) which relates
to another bean (B). This relation is annotated as @ManyToOne(cascade = CascadeType.ALL)
and
@JoinColumn(nullable = false)
The enity bean (B) has only one property beside the autogenerated id (Long) which its name
(b.getName()). This property is annotated with @Column(nullable = false, unique = true).
I use annotations over the fields of the properties.
When I persist/merge these entities I get
javax.ejb.EJBException: javax.persistence.PersistenceException:
org.hibernate.PersistentObjectException: detached entity passed to persist: a.package.B
|
The methods which tries to persist the entities are:
| public Long saveOrUpdate(A a) {
| B b = a.getB();
| b.setId(saveOrUpdate(b));
| entityManager.flush();
|
| // If b is persisted before, the persisting gives an exception
| // I have actually never tried the merge option as a.getId() is null...
|
| if (a.getId() != null) {
| entityManager.merge(a);
|
| return a.getId();
| }
|
| entityManager.persist(a);
|
| return a.getId();
| }
|
| public Long saveOrUpdate(B b) {
| B persistedB = get(b.getName());
|
| if (persistedB != null) {
| return persistedB.getId();
| }
|
| entityManager.persist(b);
|
| return b.getId();
| }
|
Since B only have one property (name) and this is unique, my saveOrUpdate method of B only
return the id of an allready saved instance. Therefore I use this id on B.setId(Long id)
when the method is called.
If B has not been persisted before it works as intended, but if the instance of B is
located in the database, then the exception is thrown when I try to persist A... When A is
persisted (even though there is a merge option in the code, every time I use this code, I
persist a new instance of A - a.getId() == null - which may have an allready persisted
instance of B) this exception is thrown even if the correct id is located in the instance
of B which is tried to be persisted with A.
Please help me with this exception. I thought a detached entity did not have a valid
primary key (b.getId()), but this is not the case in this situation. I am growing
frustrated...
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