i use three class User , Type ,and Article : @PersistenceCapable(identityType = IdentityType.APPLICATION) public class User {
@PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key id; @Persistent private String login; @Persistent private Type type; ....... } @PersistenceCapable(identityType = IdentityType.APPLICATION) public class Type { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key key; ....... } @PersistenceCapable(identityType = IdentityType.APPLICATION) public class Article { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Long id; @Persistent private User user; ..... } -------------------------------- I use this method to save the article : public static Article save(Article article, Long userId) { Article result = null; PersistenceManager pm = PMF.get().getPersistenceManager(); try { // Getting the user by id Query query = pm.newQuery(User.class, "id == idParam"); query.declareParameters("Long idParam"); List<User> users = (List<User>) query.execute(userId); User user = null; if (!users.isEmpty()) { user = users.get(0); } article.setUser(user); result = pm.makePersistent(article); } finally { pm.close(); } return result; } the exception : javax.jdo.JDOFatalUserException: Detected attempt to establish Article (16) as the parent of User(14) but the entity identified by User(14) has already been persisted without a parent. A parent cannot be established or changed once an object has been persisted. at org.datanucleus.jdo.NucleusJDOHelper.getJDOExceptionForNucleusException (NucleusJDOHelper.java:354) at org.datanucleus.jdo.JDOPersistenceManager.jdoMakePersistent (JDOPersistenceManager.java:674) at org.datanucleus.jdo.JDOPersistenceManager.makePersistent (JDOPersistenceManager.java:694) ...... thanks in advance On 25 août, 17:14, objectuser <kevin.k.le...@gmail.com> wrote: > Can you tell us what the error is? And maybe some snippits of code > showing the relevant parts of your model and how it's mapped? > > On Aug 25, 8:08 am, midomarocain <elattar...@gmail.com> wrote: > > > I have a relation between a User and Article > > > (1) User can have one or many article > > > (2) an article is owned by only one user > > > i'am intersted only by the relation (2) > > > the User is persisted > > > I create a new Article and i want relie it with an existant User > > > But i have a probleme when trying to persist the article object > > > my code is like > > > article.setUser(user); > > > pm.makePersistent(article); > > > can any one help me please --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-java@googlegroups.com To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en -~----------~----~----~----~------~----~------~--~---