jpa Hibernate EntityExistsException如果尝试延迟获取OneToOne关联

2023-04-13 06:02| 来源: 网络整理| 查看: 265

我有一对一的双向关联Account Budget。根据this，我尝试延迟加载关联：对于Account.java：

@Audited @Entity public class Account { @Id @GeneratedValue(strategy = GenerationType.TABLE) protected long id; @OneToOne(mappedBy = "account", cascade = CascadeType.ALL, orphanRemoval=true, fetch=FetchType.LAZY) private Budget mainBudget; } ... }

对于Budget.java：

@Audited @Entity public class Budget { @Id @GeneratedValue(strategy = GenerationType.TABLE) protected long id; @OneToOne(fetch=FetchType.LAZY) @MapsId private Account account; @OneToMany(targetEntity = Budget.class, cascade = CascadeType.ALL, mappedBy = "parentBudget", orphanRemoval=true) @Fetch(value = FetchMode.SUBSELECT) private List subBudget; ... }

现在，我正在尝试使用DAOClass中的create-方法创建一个新帐户，并使用新预算，如下所示：

@Resource(name = "DBRouter", type = DatabaseRouter.class) protected DatabaseRouter router; @PersistenceContext protected EntityManager em; @Transactional public D create(D d, boolean flush, String resource) { router.setDataSource(resource); if (flush) { em.flush(); } D obj = em.merge(d); if (flush) { em.flush(); } return obj; }

这给了我以下例外：

javax.persistence.EntityExistsException: A different object with the same identifier value was already associated with the session : [[PACKACKENAMES].Account#50](31 internal lines) at org.apache.openejb.persistence.JtaEntityManager.merge(JtaEntityManager.java:203) at [PACKACKENAMES].DAOClass.create(DaoClass.java:75) at [PACKACKENAMES].DaoClass.create(DaoClass.java:66) ...

如果我删除了@MapsId注解，那么我就不会有这个问题，尽管这样延迟加载就不能正常工作了。这个异常的原因是什么？如何解决？

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