Hi Carl,
JPA prohibits changing the primary key. So you're right about having to
do a copy-and-delete. I'm not too familiar with EclipseLink - what's
the exact error you're seeing? Maybe others can chime in.
Anyways, I think the easiest and most effective way is to just use
plain-ole SQL.
-- Nam
On 2/18/15 10:00 AM, resin-interest-requ...@caucho.com wrote:
> Date: Tue, 17 Feb 2015 21:04:47 +0000
> From: "c.whalley"<c.whal...@blueyonder.co.uk>
> Subject: [Resin-interest] Help with JPA
> To: General Discussion for the Resin application server
> <resin-interest@caucho.com>
> Message-ID:<54e3acef.7060...@blueyonder.co.uk>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Hi,
>
> I realise this is not the usual thing but I'm using EclipseLink under
> Resin so if anyone can help I'd really appreciate it.
> Basically I want to know a better way to achive something I feel I'm
> doing via a kludge. I have an entity for which I effectivley want to
> rename a primary key. I know thats a no-no so my approach is to create
> the new key, copy the existing fields over then delete the old one. The
> problem is I can't figure out how to do it in 1 transaction, I get
> various errors along the lines of my entities not being managed etc. I
> want to to it in the same transaction to guarantee atomicity. So, the
> kludge is to clone the key, close and persist the trans, then do another
> one just for the delete. Sorry for the verbosity. You can see the delete
> code is in the "is nameChanged(...)" section. Thanks very much in advance.
>
> Here we go:
>
> @WebServlet(value="/register", name="register-servlet")
> public class RegServlet extends HttpServlet {
> private static final Logger log =
> Logger.getLogger(RegServlet.class.getName());
> private static final long serialVersionUID = 1L;
> private Properties props;
> private String s;
>
> @PersistenceUnit(unitName="custom")
> private EntityManagerFactory emf;
> private EntityManager em;
>
> @Inject
> private UserTransaction ut;
>
> ...
>
> private void writeUser(User userToPersist) {
> User userWithSameRegId = null;
> boolean nameChanged = false;
>
> try {
> ut.begin();
> em = emf.createEntityManager();
>
> Query query = em.createQuery("select u from User u where
> u.name = ?1");
> query.setParameter(1, userToPersist.getName());
>
> User user = null;
> try {
> user = (User) query.getSingleResult();
> } catch (NoResultException nrx) {
>
> userWithSameRegId =
> findUserFromRegId(userToPersist.get_Dev_Reg_Id());
> if (userWithSameRegId != null) {
>
> log.fine(s+"RegID Existed as: " +
> userWithSameRegId.getName());
>
> user = new User();
> user.setName(userToPersist.getName());
> ...
>
> nameChanged = true;
> } else {
>
> log.fine(s+"New user");
>
> user = userToPersist;
> user.set_Reg_Count(1);
> }
> }
>
> user.set_Reg_Date(new Date());
> em.persist(user);
> em.flush();
>
> } catch (Exception e) {
> e.printStackTrace();
> } finally {
> try {
> ut.commit();
> } catch (Exception commitEx) {
> log.fine(commitEx.toString());
> }
>
> if (em != null && em.isOpen()) {
> em.close();
> }
> }
>
> if (nameChanged) {
> try {
> ut.begin();
> em = emf.createEntityManager();
>
> Query query = em.createQuery("select u from User u
> where u.name = ?1");
> query.setParameter(1, userWithSameRegId.getName());
>
> User user = null;
> try {
> user = (User) query.getSingleResult();
> em.remove(user);
> } catch (NoResultException nrx) {
>
> }
> } catch (Exception e) {
> e.printStackTrace();
> } finally {
> try {
> ut.commit();
> } catch (Exception commitEx) {
> log.fine(commitEx.toString());
> }
>
> if (em != null && em.isOpen()) {
> em.close();
> }
> }
> }
> }
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