When I try to do that, I get a following error:
java.lang.NullPointerException
at
com.google.appengine.datanucleus.StoreFieldManager.storeRelations(StoreFieldManager.java:848)
at
com.google.appengine.datanucleus.DatastorePersistenceHandler.insertObjectsInternal(DatastorePersistenceHandler.java:367)
at
com.google.appengine.datanucleus.DatastorePersistenceHandler.insertObject(DatastorePersistenceHandler.java:218)
at
org.datanucleus.state.JDOStateManager.internalMakePersistent(JDOStateManager.java:2377)
at
org.datanucleus.state.JDOStateManager.flush(JDOStateManager.java:3769)
at
org.datanucleus.state.JDOStateManager.getExternalObjectId(JDOStateManager.java:1088)
at
org.datanucleus.state.JDOStateManager.getObjectId(JDOStateManager.java:958)
at com.emajstor.server.persistence.Company.jdoGetObjectId(Company.java)
at
org.datanucleus.api.jpa.JPAAdapter.getIdForObject(JPAAdapter.java:272)
at
com.google.appengine.datanucleus.EntityUtils.getKeyForObject(EntityUtils.java:245)
at
com.google.appengine.datanucleus.EntityUtils.getParentKey(EntityUtils.java:853)
at
com.google.appengine.datanucleus.StoreFieldManager.establishEntityGroup(StoreFieldManager.java:939)
at
com.google.appengine.datanucleus.DatastorePersistenceHandler.insertObjectsInternal(DatastorePersistenceHandler.java:244)
at
com.google.appengine.datanucleus.DatastorePersistenceHandler.insertObject(DatastorePersistenceHandler.java:218)
at
org.datanucleus.state.JDOStateManager.internalMakePersistent(JDOStateManager.java:2377)
at
org.datanucleus.state.JDOStateManager.flush(JDOStateManager.java:3769)
at
org.datanucleus.ObjectManagerImpl.flushInternalWithOrdering(ObjectManagerImpl.java:3884)
at
org.datanucleus.ObjectManagerImpl.flushInternal(ObjectManagerImpl.java:3807)
at org.datanucleus.ObjectManagerImpl.flush(ObjectManagerImpl.java:3747)
at
org.datanucleus.ObjectManagerImpl.preCommit(ObjectManagerImpl.java:4137)
at
org.datanucleus.ObjectManagerImpl.transactionPreCommit(ObjectManagerImpl.java:428)
at
org.datanucleus.TransactionImpl.internalPreCommit(TransactionImpl.java:400)
at org.datanucleus.TransactionImpl.commit(TransactionImpl.java:288)
at org.datanucleus.ObjectManagerImpl.close(ObjectManagerImpl.java:1090)
at
org.datanucleus.api.jpa.JPAEntityManager.close(JPAEntityManager.java:193)
at com.emajstor.server.persistence.Company.persist(Company.java:110)
at
com.emajstor.server.test.MyTestServlet.testPersistenceOne(MyTestServlet.java:74)
at com.emajstor.server.test.MyTestServlet.doGet(MyTestServlet.java:39)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at
org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at
com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:123)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:61)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
com.google.appengine.tools.development.BackendServersFilter.doFilter(BackendServersFilter.java:97)
at
org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at
com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:94)
at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at
com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:383)
at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at
org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at
org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at
org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at
org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Am Donnerstag, 23. Mai 2013 11:50:29 UTC+2 schrieb Juan Pablo Gardella:
>
> In the loop, do user.setCompany(company). You need a transaction. Create
> it and do the commit.
>
>
> 2013/5/23 Nermin <use...@gmx.de <javascript:>>
>
>> Dear Juan,
>>
>> For this purpose I use the GWT-s Request Factory.
>> However, in order to simplify the problem, I have created a server side
>> persistence example using a simple servlet where one company and two users
>> are created. Please have a look at the MyTestServlet.java within the Zip
>> File.
>>
>> https://dl.dropboxusercontent.**com/u/2983671/JPA_Problem/JPA_**
>> Problem.zip<https://dl.dropboxusercontent.com/u/2983671/JPA_Problem/JPA_Problem.zip>
>>
>> The funny thing is, I get now a different Eror:
>>
>> javax.persistence.PersistenceException: Illegal argument
>> ....
>> Caused by: java.lang.IllegalArgumentException: cross-group transaction
>> need to be explicitly specified, see TransactionOptions.Builder.withXGfound
>> both Element {
>> type: "Tradesman"
>> id: 361
>> }
>> and Element {
>> type: "Tradesman"
>> id: 362
>> }
>>
>> When I remove the @PrePersit from "User class" it works just fine!
>> The Error pops up as soon as i modify a parameter on "Tradesman" entity
>> (more exactly on its parent class "User").
>>
>> I really do not understand this behavior. ... I also must admit that I am
>> not very advanced in JPA.
>>
>> Thank you for very much for your help.
>>
>> Best regards:
>>
>> Nermin
>>
>>
>> Am Mittwoch, 22. Mai 2013 15:28:50 UTC+2 schrieb Juan Pablo Gardella:
>>>
>>> Show how you are persisting the entities.
>>>
>>>
>>> 2013/5/22 Nermin <use...@gmx.de>
>>>
>>>> Dear Alfredo and Juan,
>>>>
>>>> obviously there is an hidden problem with my code i simply do not see.
>>>> Could you please have a short look at these 3 classes (full code) and
>>>> tell me what am I doing wrong here:
>>>>
>>>> https://dl.dropboxusercontent.**com/u/2983671/JPA_Problem/JPA_**
>>>> Problem.zip<https://dl.dropboxusercontent.com/u/2983671/JPA_Problem/JPA_Problem.zip>
>>>>
>>>> Please note: Everything works fine as log as I do not try to make any
>>>> changes to the Tradesman entity (its parameters).
>>>> When is set new password or any other parameter, i get an error message
>>>> of type:
>>>>
>>>> Detected attempt to establish Company(no-id-yet) as the parent of
>>>> Tradesman(358) but the entity identified by Tradesman(358) has already
>>>> been
>>>> persisted without a parent. A parent cannot be established or changed
>>>> once
>>>> an object has been persisted.
>>>>
>>>> I am using: JPA with DataNucleus on Google Datastore. (Standard setting
>>>> that come with GWT 2.5)
>>>>
>>>> Thank you in advance for your help!!
>>>>
>>>> Best regards:
>>>>
>>>> Nermin
>>>>
>>>>
>>>> Am Dienstag, 21. Mai 2013 18:29:54 UTC+2 schrieb Alfredo
>>>> Quiroga-Villamil:
>>>>>
>>>>> Or use a cascade persist, merge to force creation or merge respectively
>>>>>
>>>>> Sent from my iPhone
>>>>>
>>>>> On May 21, 2013, at 7:02 AM, Juan Pablo Gardella <
>>>>> gardella...@gmail.com> wrote:
>>>>>
>>>>> You should persist company before persist Tradesman or attach to an
>>>>> existent company. This relation should be explicit. Create
>>>>> company.addTrademan(Trademan t) method:
>>>>>
>>>>> company.addTrademan(Trademan t){
>>>>> users.add(t);
>>>>> t.setCompany(this);
>>>>> }
>>>>>
>>>>> Call this in a transactional method.
>>>>>
>>>>> Juan
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> 2013/5/21 Nermin <use...@gmx.de>
>>>>>
>>>>>> Dear Juan,
>>>>>>
>>>>>> I tried *@ManyToOne(optional=false)*, unfortunately no changes.
>>>>>> In my current setting, the @PrePersist is called only once. (I see it
>>>>>> on system out) That means: no multiple attempts to persist Tradesman
>>>>>> entity.
>>>>>>
>>>>>> However, it looks to me that whenever I change parameters on the
>>>>>> Tradesman entity JPA creates/persists for some reason the Tradesman in
>>>>>> the
>>>>>> DB, independently from the Company entity.
>>>>>> I use Standard GWT settings: GWT 2.5, DataNucleus on Appengine
>>>>>> Datastore.
>>>>>>
>>>>>> The scenario I am describing here is a standard scenario you will
>>>>>> face when using GWT with JPA. I am surprised that my code is not working.
>>>>>> @PrePersist works fine as long as the Entity is not in a owned
>>>>>> relation with other entities.
>>>>>>
>>>>>> Does anyone has an idea what could be wrong here?
>>>>>>
>>>>>> Thank you!!
>>>>>>
>>>>>> Nermin
>>>>>>
>>>>>> @Thomas: Thank you for the advise. I will
>>>>>>
>>>>>> Am Dienstag, 21. Mai 2013 12:01:43 UTC+2 schrieb Juan Pablo Gardella:
>>>>>>>
>>>>>>> Update your entity as:
>>>>>>>
>>>>>>> @Entity
>>>>>>> public class Tradesman extends User{
>>>>>>> @ManyToOne(optional=false)
>>>>>>> private Company company;
>>>>>>>
>>>>>>> *@PrePersist*
>>>>>>> public void hashPassword(){
>>>>>>> setPassword(BCrypt.hashpw(**enti******ty.getPassword(),
>>>>>>> BCrypt.gensalt());
>>>>>>> }
>>>>>>>
>>>>>>> And then check where are you persisting Tradesman without company.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> 2013/5/21 Thomas Broyer <t.br...@gmail.com>
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tuesday, May 21, 2013 11:18:42 AM UTC+2, Nermin wrote:
>>>>>>>>>
>>>>>>>>> Dear GWT developers,
>>>>>>>>>
>>>>>>>>> I have a "probably simple" problem with my application which I am
>>>>>>>>> obviously not able to solve.
>>>>>>>>>
>>>>>>>>> Two Classes: Company, Tradesman
>>>>>>>>>
>>>>>>>>> @Entity
>>>>>>>>> public class Company {
>>>>>>>>> @OneToMany(cascade = CascadeType.ALL, mappedBy = "company")
>>>>>>>>> private List<Tradesman> users = new ArrayList<Tradesman>();
>>>>>>>>>
>>>>>>>>> ....
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> @Entity
>>>>>>>>> public class Tradesman extends User{
>>>>>>>>> @ManyToOne
>>>>>>>>> private Company company;
>>>>>>>>>
>>>>>>>>> *@PrePersist*
>>>>>>>>> public void hashPassword(){
>>>>>>>>> setPassword(BCrypt.hashpw(**enti******ty.getPassword(),
>>>>>>>>> BCrypt.gensalt());
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> *JSR 303 validation on GWT is activated.*
>>>>>>>>>
>>>>>>>>> Here is the *error message:
>>>>>>>>> *Detected attempt to establish Company(no-id-yet) as the parent
>>>>>>>>> of Tradesman(356) but the entity identified by Tradesman(356) has
>>>>>>>>> already
>>>>>>>>> been persisted without a parent. A parent cannot be established or
>>>>>>>>> changed
>>>>>>>>> once an object has been persisted.
>>>>>>>>>
>>>>>>>>> My problem is obviously that when I change some parameters within
>>>>>>>>> the Tradesman entity within the *@PrePersist* method, a new child
>>>>>>>>> entity is created.
>>>>>>>>> In case I do not touch any parameter, in the @PrePersist,
>>>>>>>>> everything works fine.
>>>>>>>>>
>>>>>>>>> What am I doing wrong here?
>>>>>>>>>
>>>>>>>>
>>>>>>>> You're not reaching the appropriate group ;-)
>>>>>>>>
>>>>>>>> I suppose you're using AppEngine (form what I know of JPA, I can't
>>>>>>>> see a reason for that kind of message, unless you're using JPA on
>>>>>>>> AppEngine), in which case you can ask for support on StackOverflow:
>>>>>>>> https://**develop****ers.google.com/**appengine/**commu**nity<https://developers.google.com/appengine/community>
>>>>>>>>
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