我有以下 JSON:
{
id: 123,
subObjects: [
{
id: 564,
name: "foo",
contry: {
id: 1,
name: "Germany"
}
},
{
id: 777,
name: "bar",
contry: {
id: 1,
name: "Germany"
}
}
]
}
并使用 Gson 对其进行反序列化。之后我需要合并 JPA 实体:
Model model = new Gson().fromJson(json, modelClass);
model = entityManager.merge(model)
刷新从模型级联到子对象,再级联到国家/地区。
这会导致 Hibernate 出现异常“实体副本已分配给不同的实体”。
如果我使用不同的国家/地区,它会起作用。
如果我使用将国家/地区实例从一个对象复制到另一个对象中,这样两个子对象都引用该国家/地区的同一实例,则它会起作用。
两国都有相同的价值观。两者都有相同的 hashCode,to。
两国是平等的,但不是==,因为它们是不同的实例。
列出的提示这个问题 https://stackoverflow.com/questions/10550511/illegalstateexception-with-hibernate-4-and-manytoone-cascading没有帮助我。
我正在使用 Hibernate 4.1.3 Final 和 Gson 2.2
java.lang.IllegalStateException: An entity copy was already assigned to a different entity.
at org.hibernate.event.internal.EventCache.put(EventCache.java:184)
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:285)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:914)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:896)
at org.hibernate.engine.spi.CascadingAction$6.cascade(CascadingAction.java:288)
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:380)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:323)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:165)
at org.hibernate.event.internal.DefaultMergeEventListener.cascadeOnMerge(DefaultMergeEventListener.java:439)
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:308)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:914)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:896)
at org.hibernate.engine.spi.CascadingAction$6.cascade(CascadingAction.java:288)
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:380)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:323)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:409)
at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:350)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:326)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:165)
at org.hibernate.event.internal.DefaultMergeEventListener.cascadeOnMerge(DefaultMergeEventListener.java:439)
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:308)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:76)
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:904)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:888)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:892)
at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:874)
at play.db.jpa.GenericModel.merge(GenericModel.java:234)
[...]
如何以通用方式解决这个问题,我不需要知道对象类型以及哪些对象在逻辑上是相同的?