App Engine的ORM不支持多父键提供商领域

我有问题映射JPA中的父/子关系，目前与后续的错误消息下来 -App Engine的ORM不支持多父键提供商领域

java.lang.IllegalArgumentException: org.datanucleus.exceptions.NucleusException: App Engine ORM does not support multiple parent key provider fields. 
at org.datanucleus.jpa.EntityManagerImpl.find(EntityManagerImpl.java:232) 
at org.datanucleus.store.appengine.jpa.DatastoreEntityManager.find(DatastoreEntityManager.java:56) 
at bios.model.DAO.StudentDAO.retrieveStudent(StudentDAO.java:31) 
at bios.model.manager.StudentMgr.authenticateStudent(StudentMgr.java:27) 
at bios.controller.AuthenticateServlet.doPost(AuthenticateServlet.java:99) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:713) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) 
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) 
at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:51) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) 
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) 
at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:122) 
at org.mortbay.jetty.servlet.ServletHandler$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.apphosting.utils.jetty.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:70) 
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:349) 
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) 
at org.mortbay.jetty.Server.handle(Server.java:326) 
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) 
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938) 
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755) 
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218) 
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) 
Caused by: org.datanucleus.exceptions.NucleusException: App Engine ORM does not support multiple parent key provider fields. 
at org.datanucleus.store.appengine.DatastoreTable.markFieldAsParentKeyProvider(DatastoreTable.java:477) 
at org.datanucleus.store.appengine.DatastoreTable.initializeNonPK(DatastoreTable.java:399) 
at org.datanucleus.store.appengine.DatastoreTable.buildMapping(DatastoreTable.java:288) 
at org.datanucleus.store.appengine.DatastoreManager.buildStoreData(DatastoreManager.java:479) 
at org.datanucleus.store.appengine.DatastoreManager.newStoreData(DatastoreManager.java:437) 
at org.datanucleus.store.AbstractStoreManager.addClasses(AbstractStoreManager.java:788) 
at org.datanucleus.store.AbstractStoreManager.addClass(AbstractStoreManager.java:759) 
at org.datanucleus.store.mapped.MappedStoreManager.getDatastoreClass(MappedStoreManager.java:358) 
at org.datanucleus.store.appengine.DatastoreManager.getDatastoreClass(DatastoreManager.java:709) 
at org.datanucleus.store.appengine.DatastoreManager.getDatastoreClass(DatastoreManager.java:87) 
at org.datanucleus.store.appengine.DatastoreTable.initializeNonPK(DatastoreTable.java:393) 
at org.datanucleus.store.appengine.DatastoreTable.buildMapping(DatastoreTable.java:288) 
at org.datanucleus.store.appengine.DatastoreManager.buildStoreData(DatastoreManager.java:479) 
at org.datanucleus.store.appengine.DatastoreManager.newStoreData(DatastoreManager.java:437) 
at org.datanucleus.store.AbstractStoreManager.addClasses(AbstractStoreManager.java:788) 
at org.datanucleus.store.AbstractStoreManager.addClass(AbstractStoreManager.java:759) 
at org.datanucleus.store.mapped.MappedStoreManager.getDatastoreClass(MappedStoreManager.java:358) 
at org.datanucleus.store.appengine.DatastoreManager.getDatastoreClass(DatastoreManager.java:709) 
at org.datanucleus.store.appengine.DatastoreManager.getDatastoreClass(DatastoreManager.java:87) 
at org.datanucleus.store.mapped.mapping.PersistenceCapableMapping.prepareDatastoreMapping(PersistenceCapableMapping.java:198) 
at org.datanucleus.store.mapped.mapping.PersistenceCapableMapping.initialize(PersistenceCapableMapping.java:117) 
at org.datanucleus.store.mapped.mapping.MappingFactory.createMapping(MappingFactory.java:97) 
at org.datanucleus.store.mapped.mapping.AbstractMappingManager.getMapping(AbstractMappingManager.java:248) 
at org.datanucleus.store.appengine.DatastoreTable.initializeNonPK(DatastoreTable.java:322) 
at org.datanucleus.store.appengine.DatastoreTable.buildMapping(DatastoreTable.java:288) 
at org.datanucleus.store.appengine.DatastoreManager.buildStoreData(DatastoreManager.java:479) 
at org.datanucleus.store.appengine.DatastoreManager.newStoreData(DatastoreManager.java:437) 
at org.datanucleus.store.AbstractStoreManager.addClasses(AbstractStoreManager.java:788) 
at org.datanucleus.store.AbstractStoreManager.addClass(AbstractStoreManager.java:759) 
at org.datanucleus.ObjectManagerImpl.newObjectId(ObjectManagerImpl.java:2508) 
at org.datanucleus.jpa.EntityManagerImpl.find(EntityManagerImpl.java:228) 
... 31 more

这里是我的学生

@Entity 
@Table(name="STUDENT") 
public class Student { 

    @Id 
    @Column(name="userid") 
    private String userid; 

    @OneToMany(mappedBy = "student", targetEntity = Phone.class, 
     fetch = FetchType.EAGER, cascade = CascadeType.ALL) 
    private List<Phone> phoneList = new ArrayList<Phone>();

代码

这是我的电话课程。

@Entity 
@Table(name="PHONE") 
public class Phone { 
    @Id 
    @Column(name="id") 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private Key id; 

    @ManyToOne(fetch = FetchType.EAGER) 
    @JoinColumn(name="userid") 
    private Student student;

请帮忙！谢谢！ :)

来源

2010-09-27 teo

以防万一，看看Issue 1276（这是无效的）。引用Max Ross：

作为例外状态，在App Engine上，实体不能有多个父母。这个是因为OneToMany与数据存储中的祖先概念相关联。每个实体只能有一个直接祖先。

你真的显示了所有的代码吗？

来源

2010-09-27 03:57:04

嗨帕斯卡尔。谢谢回复。以下是完整的代码： – teo 2010-09-27 05:02:14

@teo这证实了我的答案，一个实体在GAE/J上不能有多个父母。改为使用成组的键[如文档]（http://code.google.com/appengine/docs/java/datastore/relationships.html#Unowned_Relationships）（我写作“如记录”，但我认为文档很糟糕）。 – 2010-09-27 21:49:17

//学生的实体类 @Entity @Table（name = “学生”）公共类学生{

@Id 
    @Column(name="userid")

私人字符串userid;

@OneToMany(mappedBy = "student", 
    targetEntity = Bid.class, 
    fetch = FetchType.EAGER, cascade = CascadeType.ALL) 
    private List<Phone> phoneList = new ArrayList<Phone>(); 

    @Basic 
    @Column(name="password")

private String password;

@Basic 
    @Column(name="name")

private String name;

@Basic 
    @Column(name="school")

private String school;

//电话实体类 @Entity @Table（name = “手机”）公共类电话{

@Id 
    @Column(name="id") 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private Key id; 

    @ManyToOne(fetch = FetchType.EAGER) 
    @JoinColumn(name="userid")

私人学生的学生;

@Basic 
    @Column(name="number")

private int number;

@ManyToOne(fetch = FetchType.EAGER) 
    @JoinColumn(name="code")

私人课程代码;

@ManyToOne(fetch = FetchType.EAGER) 
    @JoinColumn(name="section")

private Section section;

来源

2010-09-27 05:09:27 teo

App Engine的ORM不支持多父键提供商领域

回答

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