Hi,
read the last entry by Ikai Lan in this thread
http://groups.google.com/group/google-appengine-java/browse_thread/thread/defc6d14445318b8/75a1e7b5bcbc1bb3#75a1e7b5bcbc1bb3
Maybe you should switch to a 3rd party package instead of JDO that
seems to have an uncertain future and represents anyway the majority
of the isssues in this group.
I personally switched (happily) to Objectify.
regards
didier
On Dec 1, 5:35 pm, clement boret <boret.clem...@gmail.com> wrote:
> PLEASE HELP?§
>
> On Nov 27, 2:28 pm, clement boret <boret.clem...@gmail.com> wrote:
>
> > hello.
> > I have a problem when trying to update an object that has already been
> > saved in the dataStore....
> > An Employee and Contactnfo. One employee has a contactInfo...
>
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > @PersistenceCapable(detachable = "true")
> > public class Employee implements Serializable {
>
> > @PrimaryKey
> > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> > private Key key;
>
> > @Persistent
> > private ContactInfo contactInfo = null;
>
> > public ContactInfo getContactInfo() {
> > return contactInfo;
> > }
>
> > public void setContactInfo(ContactInfo contactInfo) {
> > this.contactInfo = contactInfo;
> > }
>
> > public Key getKey() {
> > return key;
> > }}
>
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > @PersistenceCapable(detachable = "true")
> > public class ContactInfo implements Serializable {
>
> > @PrimaryKey
> > @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> > private Key key;
>
> > @Persistent
> > private String name;
>
> > public String getName() {
> > return name;
> > }
>
> > public void setName(String name) {
> > this.name = name;
> > }
>
> > public Key getKey() {
> > return key;
> > }
>
> > public void setKey(Key key) {
> > this.key = key;
> > }}
>
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > ///////////////////////////////////////////////////////////////////////////
> > ///////////
> > my servlet:
>
> > public class GreetingServiceImpl extends RemoteServiceServlet
> > implements GreetingService {
>
> > private static final PersistenceManagerFactory pmfInstance =
> > JDOHelper.getPersistenceManagerFactory("transactions-optional");
>
> > public String greetServer(String input) {
> > String result = "";
>
> > //step1 create and save an employee in the datastore.
> > Key key = storeEmployeeInDatastore();
>
> > //step2 retrieve the employee from the datastore and detach it
> > Employee detachedEmployee = getDetachedEmployee(key);
>
> > //step3 modify the detached employee
> > ContactInfo contactInfo2 = new ContactInfo();
> > detachedEmployee.setContactInfo(contactInfo2);
>
> > //step4 save the modified employee...
> > updateEmployeeInDataStore(detachedEmployee);
>
> > return result;
> > }
>
> > /**
> > * @return the key of the employee that has been stored
> > */
> > private Key storeEmployeeInDatastore() {
> > Employee employee = new Employee();
> > ContactInfo contactInfo = new ContactInfo();
> > employee.setContactInfo(contactInfo);
>
> > //creates a new manager.
> > PersistenceManager manager1 = pmfInstance.getPersistenceManager();
> > Key key = null;
>
> > try {
> > manager1.makePersistent(employee);
> > key = employee.getKey();
> > }
> > catch ( Exception e ) {
> > e.printStackTrace();
> > }
> > finally {
> > //equivalent to manager1.close()
> > manager1.close();
> > }
> > return key;
> > }
>
> > private Employee getDetachedEmployee(Key key) {
> > PersistenceManager manager2 = pmfInstance.getPersistenceManager();
> > Employee attached = manager2.getObjectById(Employee.class, key);
>
> > Employee detachedEmployee = manager2.detachCopy(attached);
> > manager2.close();
> > return detachedEmployee;
> > }
>
> > private void updateEmployeeInDataStore(Employee detachedEmployee) {
> > PersistenceManager manager3 = pmfInstance.getPersistenceManager();
> > try {
>
> > Employee bidon = manager3.makePersistent(detachedEmployee);
>
> > System.out.println("");
> > }
> > catch ( Exception e ) {
> > e.printStackTrace();
> > }
> > finally {
> > manager3.close();
> > }
> > }
>
> > }
>
> > ///////////////////////////////////////////////////////////////////////////
> > ////////
> > ///////////////////////////////////////////////////////////////////////////
> > ////////
> > ///////////////////////////////////////////////////////////////////////////
> > ////////
> > HERE IS THE ERROR I GET
> > org.datanucleus.store.appengine.DatastoreRelationFieldManager
> > $ChildWithoutParentException: Detected attempt to establish
> > Employee(4) as the parent of ContactInfo(6) but the entity identified
> > by ContactInfo(6) 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(Nuc
> > leusJDOHelper.java:
> > 354)
> > at
> > org.datanucleus.jdo.JDOPersistenceManager.close(JDOPersistenceManager.java:
> > 281)
> > at
> > com.gae.server.GreetingServiceImpl.updateEmployeeInDataStore(GreetingServic
> > eImpl.java:
> > 85)
> > at
> > com.gae.server.GreetingServiceImpl.greetServer(GreetingServiceImpl.java:
> > 33)
> > at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> > at
> > sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:
> > 39)
> > at
> > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImp
> > l.java:
> > 25)
> > at java.lang.reflect.Method.invoke(Method.java:597)
> > at
> > com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime
> > .java:
> > 100)
> > at
> > com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:
> > 562)
>
> > ///////////////////////////////////////////////////////////////////////////
> > /////////////
>
> > Can Anyone explain me what's wrong... and can anyone explain to me how
> > I can do the 4 steps!
>
> > //step1 create and save an employee in the datastore.
>
> > //step2 retrieve the employee from the datastore and detach it
>
> > //step3 modify the detached employee
>
> > //step4 save the modified employee...
>
> > Thank you in advance.
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