thank you for a fast reply.
Yes I would like to use unidirectional mapping, but in combination with @PrePersist method at a child entity which changes one parameter value.
Here is my code:
@Entity
public class CompanyUD {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@org.datanucleus.api.jpa.annotations.Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value = "true")
private String id;
@OneToOne(cascade=CascadeType.ALL)
@JoinColumn(name="admin_user")
TradesmanUD adminUser;
private String name;
.. get / Set
}
@Entity
public class TradesmanUD {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@org.datanucleus.api.jpa.annotations.Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value = "true")
private String id;
private String name;
// @PrePersist
// public void myPrePers(){
// setName("Some different Name");
// }
.. get / set
}
// ====== My call:
private void testOneToOne() {
CompanyUD company = new CompanyUD();
company.setName("MyTest Company");
TradesmanUD user = new TradesmanUD();
user.setName("My test Admin");
company.setAdminUser(user);
EntityManager em = emfInstance.createEntityManager();
em.persist(company);
em.close();
}
The code above works fine without the @PrePersist method at TradesmanUD (UD stays for unidirectional)
With @PrePersist in place i get the following ERROR:
Detected attempt to establish CompanyUD(no-id-yet) as the parent of TradesmanUD(52) but the entity identified by TradesmanUD(52) 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 Appengine.
Thank you for your help!
Nermin
Am Mittwoch, 5. Juni 2013 16:03:59 UTC+2 schrieb Juan Pablo Gardella:
--I've assumed you are trying to use unidirectional mapping. Check http://uaihebert.com/?p=1674&page=19
2013/6/5 Nermin <use...@gmx.de>Dear Juan, Dear GWT Group
thank you very much for your help. I fixed most of my problems by following your advice. All @OneToMany relations work fine after I made sure the @ManyToOne relation is populated manually as you suggested.
Unfortunately I cannot get @OneToOne relation running wen @PrePerist is used on a child.
My sample code is here:
https://dl.dropboxusercontent.com/u/2983671/JPA_Problem/JPA_ Problem.zip
Two Classes: CompanyX, TradesmanX
CompanyX stays in a OneToOne owned relation with TradesmanX
I use @PrePersist on TradesmanX in order to pre-set some fields before the Object gets persisted in the DB.
@Entity
public class CompanyX {
...
@OneToOne(cascade=CascadeType.ALL)
private TradesmanX adminUser;
}
@Entity
public class TradesmanX {
...
@PrePersist
public void myMethod(){
System.out.println("Pre Persist");
this.setFirstName("USER_XXXXX");
}
...
}
//Here is how I persist them within my test servlet:
private void testPersistenceTwo() {
CompanyX company = new CompanyX();
company.setName("my Comp");
TradesmanX user = new TradesmanX();
user.setFirstName("Test_FName");
user.setLastName("Test_Lname");
company.setAdminUser(user);
company.persist();
}
I am getting a similar error to the previous one:
javax.persistence.PersistenceException: Detected attempt to establish CompanyX(no-id-yet) as the parent of TradesmanX(7) but the entity identified by TradesmanX(7) has already been persisted without a parent. A parent cannot be established or changed once an object has been persisted.
Is there a solution for this?
Would it be possible to provide some working example?
Thank you in advance:
Nermin
Am Donnerstag, 23. Mai 2013 15:09:41 UTC+2 schrieb Nermin:When I try to do that, I get a following error:--java.lang.NullPointerException at com.google.appengine.datanucleus.StoreFieldManager.storeRela tions(StoreFieldManager.java: 848) at com.google.appengine.datanucle us.DatastorePersistenceHandler .insertObjectsInternal(Datasto rePersistenceHandler.java:367) at com.google.appengine.datanucle us.DatastorePersistenceHandler .insertObject(DatastorePersist enceHandler.java:218) at org.datanucleus.state.JDOState Manager.internalMakePersistent (JDOStateManager.java:2377) at org.datanucleus.state.JDOState Manager.flush(JDOStateManager. java:3769) at org.datanucleus.state.JDOState Manager.getExternalObjectId(JD OStateManager.java:1088) at org.datanucleus.state.JDOState Manager.getObjectId(JDOStateMa nager.java:958) at com.emajstor.server.persistenc e.Company.jdoGetObjectId( Company.java) at org.datanucleus.api.jpa.JPAAda pter.getIdForObject(JPAAdapter .java:272) at com.google.appengine.datanucle us.EntityUtils.getKeyForObject (EntityUtils.java:245) at com.google.appengine.datanucle us.EntityUtils.getParentKey( EntityUtils.java:853) at com.google.appengine.datanucle us.StoreFieldManager.establish EntityGroup(StoreFieldManager. java:939) at com.google.appengine.datanucle us.DatastorePersistenceHandler .insertObjectsInternal(Datasto rePersistenceHandler.java:244) at com.google.appengine.datanucle us.DatastorePersistenceHandler .insertObject(DatastorePersist enceHandler.java:218) at org.datanucleus.state.JDOState Manager.internalMakePersistent (JDOStateManager.java:2377) at org.datanucleus.state.JDOState Manager.flush(JDOStateManager. java:3769) at org.datanucleus.ObjectManagerI mpl.flushInternalWithOrdering( ObjectManagerImpl.java:3884) at org.datanucleus.ObjectManagerI mpl.flushInternal(ObjectManage rImpl.java:3807) at org.datanucleus.ObjectManagerI mpl.flush(ObjectManagerImpl. java:3747) at org.datanucleus.ObjectManagerI mpl.preCommit(ObjectManagerImp l.java:4137) at org.datanucleus.ObjectManagerI mpl.transactionPreCommit(Objec tManagerImpl.java:428) at org.datanucleus.TransactionImp l.internalPreCommit(Transactio nImpl.java:400) at org.datanucleus.TransactionImp l.commit(TransactionImpl.java: 288) at org.datanucleus.ObjectManagerI mpl.close(ObjectManagerImpl. java:1090) at org.datanucleus.api.jpa.JPAEnt ityManager.close(JPAEntityMana ger.java:193) at com.emajstor.server.persistenc e.Company.persist(Company. java:110) at com.emajstor.server.test.MyTes tServlet.testPersistenceOne(My TestServlet.java:74) at com.emajstor.server.test.MyTes tServlet.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.Serv letHolder.handle(ServletHolder .java:511) at org.mortbay.jetty.servlet.Serv letHandler$CachedChain.doFilte r(ServletHandler.java:1166) at com.google.appengine.api.socke t.dev.DevSocketFilter.doFilter (DevSocketFilter.java:74) at org.mortbay.jetty.servlet.Serv letHandler$CachedChain.doFilte r(ServletHandler.java:1157) at com.google.appengine.tools.dev elopment.ResponseRewriterFilte r.doFilter(ResponseRewriterFil ter.java:123) at org.mortbay.jetty.servlet.Serv letHandler$CachedChain.doFilte r(ServletHandler.java:1157) at com.google.appengine.tools.dev elopment.HeaderVerificationFil ter.doFilter(HeaderVerificatio nFilter.java:34) at org.mortbay.jetty.servlet.Serv letHandler$CachedChain.doFilte r(ServletHandler.java:1157) at com.google.appengine.api.blobs tore.dev.ServeBlobFilter.doFil ter(ServeBlobFilter.java:61) at org.mortbay.jetty.servlet.Serv letHandler$CachedChain.doFilte r(ServletHandler.java:1157) at com.google.apphosting.utils.se rvlet.TransactionCleanupFilter .doFilter(TransactionCleanupFi lter.java:43) at org.mortbay.jetty.servlet.Serv letHandler$CachedChain.doFilte r(ServletHandler.java:1157) at com.google.appengine.tools.dev elopment.StaticFileFilter.doFi lter(StaticFileFilter.java: 125) at org.mortbay.jetty.servlet.Serv letHandler$CachedChain.doFilte r(ServletHandler.java:1157) at com.google.appengine.tools.dev elopment.BackendServersFilter. doFilter(BackendServersFilter. java:97) at org.mortbay.jetty.servlet.Serv letHandler$CachedChain.doFilte r(ServletHandler.java:1157) at org.mortbay.jetty.servlet.Serv letHandler.handle(ServletHandl er.java:388) at org.mortbay.jetty.security.Sec urityHandler.handle(SecurityHa ndler.java:216) at org.mortbay.jetty.servlet.Sess ionHandler.handle(SessionHandl er.java:182) at org.mortbay.jetty.handler.Cont extHandler.handle(ContextHandl er.java:765) at org.mortbay.jetty.webapp.WebAp pContext.handle(WebAppContext. java:418) at com.google.appengine.tools.dev elopment.DevAppEngineWebAppCon text.handle(DevAppEngineWebApp Context.java:94) at org.mortbay.jetty.handler.Hand lerWrapper.handle(HandlerWrapp er.java:152) at com.google.appengine.tools.dev elopment.JettyContainerService $ApiProxyHandler.handle(JettyC ontainerService.java:383) at org.mortbay.jetty.handler.Hand lerWrapper.handle(HandlerWrapp er.java:152) at org.mortbay.jetty.Server.handl e(Server.java:326) at org.mortbay.jetty.HttpConnecti on.handleRequest(HttpConnectio n.java:542) at org.mortbay.jetty.HttpConnecti on$RequestHandler.headerComple te(HttpConnection.java:923) at org.mortbay.jetty.HttpParser.p arseNext(HttpParser.java:547) at org.mortbay.jetty.HttpParser.p arseAvailable(HttpParser.java: 212) at org.mortbay.jetty.HttpConnecti on.handle(HttpConnection.java: 404) at org.mortbay.io.nio.SelectChann elEndPoint.run(SelectChannelEn dPoint.java:409) at org.mortbay.thread.QueuedThrea dPool$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>
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
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.wit hXGfound 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
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 iPhoneYou 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(entity.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(entity.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
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