Question

在我在WAS 6.1上部署的EJB项目中，当我尝试调用EntityManamger.merge（obj）时，我得到了这个异常：

Exception data: <openjpa-1.0.4-SNAPSHOT-r420667:955062 nonfatal store error> org.apache.openjpa.persistence.EntityExistsException: Attempt to persist detached object "com.data.entity.SomeEntity@23aa23aa".  If this is a new instance, make sure any versino and/or auto-generated primary key fields are null/default when persisting.
FailedObject: com.bmo.ctp.data.entity.attribute.RoleResServiceAttribute@23aa23aa
    at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2368)
    at org.apache.openjpa.kernel.AttachStrategy.persist(AttachStrategy.java:94)
    at org.apache.openjpa.kernel.VersionAttachStrategy.attach(VersionAttachStrategy.java:95)
    at org.apache.openjpa.kernel.AttachManager.attach(AttachManager.java:241)
    at org.apache.openjpa.kernel.AttachStrategy.attachCollection(AttachStrategy.java:333)
    at org.apache.openjpa.kernel.AttachStrategy.replaceCollection(AttachStrategy.java:301)
    at org.apache.openjpa.kernel.AttachStrategy.attachField(AttachStrategy.java:220)
    at org.apache.openjpa.kernel.VersionAttachStrategy.attach(VersionAttachStrategy.java:157)
    at org.apache.openjpa.kernel.AttachManager.attach(AttachManager.java:241)
    at org.apache.openjpa.kernel.AttachManager.attach(AttachManager.java:101)
    at org.apache.openjpa.kernel.BrokerImpl.attach(BrokerImpl.java:3161)
    at org.apache.openjpa.kernel.DelegatingBroker.attach(DelegatingBroker.java:1142)
    at org.apache.openjpa.persistence.EntityManagerImpl.merge(EntityManagerImpl.java:665)
    at com.ibm.ws.jpa.management.JPAExEmInvocation.merge(JPAExEmInvocation.java:335)
    at com.ibm.ws.jpa.management.JPAEntityManager.merge(JPAEntityManager.java:123)

我没有JPAEntityManager.java的来源;但我认为merge()操作不能抛出EntityExistsException，因为merge首先会检查实体是否存在。如果没有，请插入它。如果是，请更新它。这里出了什么问题？

Answer 1

请检查您的实体经理如何检查实体的存在。它是否使用缓存？或者它是否使用数据库查询。如果存在检查是通过缓存完成的，则通常会发生此问题。

如果您使用的是eclipselink JPA，则此配置将在orm.xml中维护

谢谢，阿南德

EntityManager合并抛出EntityExists异常

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