Question

我在模型中使用单向一对多关系。我有几张桌子，我想成为许多其他桌子的孩子。我希望通过通用外键实现这一目标。我使用UUID作为代理键，因此冲突不是问题。

Hibernate不喜欢它。这可能是使用Hibernate还是我被迫在我的共享子表中为每个关系定义一个外键？

原谅Scala。它仍应说明这一点。

类和映射：

@javax.persistence.Table(name = "ac_section")
@javax.persistence.Entity
class Section {
   @javax.persistence.Id
   @GeneratedValue(generator = "uuid")
   @org.hibernate.annotations.GenericGenerator(name = "uuid", strategy = "uuid2")
   @org.hibernate.annotations.Type(`type`="pg-uuid")
   @BeanProperty var id : UUID = UUID.randomUUID()      

    ... 

   @scala.beans.BeanProperty
   @javax.persistence.OneToMany(fetch=javax.persistence.FetchType.EAGER, cascade=Array(javax.persistence.CascadeType.ALL), orphanRemoval = true)
   @javax.persistence.JoinColumn(name="generic_fk", referencedColumnName = "id", nullable = false, updatable = false, insertable = false)
   var sectionCoords:java.util.List[Coordinate] = new java.util.LinkedList[Coordinate]

}


@javax.persistence.Table(name = "ac_spot")
@javax.persistence.Entity
class Spot {
   @javax.persistence.Id
   @GeneratedValue(generator = "uuid")
   @org.hibernate.annotations.GenericGenerator(name = "uuid", strategy = "uuid2")
   @org.hibernate.annotations.Type(`type`="pg-uuid")
   @BeanProperty var id : UUID = UUID.randomUUID()         

   @org.hibernate.annotations.Type(`type`="pg-uuid")
   @scala.beans.BeanProperty
   @javax.persistence.Column(name = "section_id", insertable = false, updatable = false)
   var sectionId:java.util.UUID = _

 ...

   @scala.beans.BeanProperty
   @javax.persistence.OneToMany(fetch=javax.persistence.FetchType.EAGER, cascade=Array(javax.persistence.CascadeType.ALL), orphanRemoval = true)
   @javax.persistence.JoinColumn(name="generic_fk", referencedColumnName = "id", nullable = false, updatable = false, insertable = false)
   var spotCoords:java.util.List[Coordinate] = new java.util.LinkedList[Coordinate]

}


@javax.persistence.Table(name = "ac_coordinate")
@javax.persistence.Entity
class Coordinate {
   @GeneratedValue(generator = "uuid")
   @org.hibernate.annotations.GenericGenerator(name = "uuid", strategy = "uuid2")
   @org.hibernate.annotations.Type(`type`="pg-uuid")
   @BeanProperty var id : UUID = UUID.randomUUID()      

   @org.hibernate.annotations.Type(`type`="pg-uuid")
   @scala.beans.BeanProperty
   @javax.persistence.Column(name = "generic_fk", insertable = false, updatable = false)
   var genericFk:java.util.UUID = _

   ...

}

当持久单元启动时，我得到一个例外：

 javax.persistence.PersistenceException: [PersistenceUnit: testPU] Unable to build EntityManagerFactory
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:924)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:899)
    at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:59)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:63)
    at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:47)
    at com.aziosoft.auctoweb.util.TestBase.before(TestBase.scala:22)
    ...
Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: com.aziosoft.auctoweb.model.Coordinate column: generic_fk (should be mapped with insert="false" update="false")
    at org.hibernate.mapping.PersistentClass.checkColumnDuplication(PersistentClass.java:696)
    at org.hibernate.mapping.PersistentClass.checkPropertyColumnDuplication(PersistentClass.java:718)
    at org.hibernate.mapping.PersistentClass.checkColumnDuplication(PersistentClass.java:740)
    at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:493)
    at org.hibernate.mapping.RootClass.validate(RootClass.java:270)
    at org.hibernate.cfg.Configuration.validate(Configuration.java:1324)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1786)
    at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:96)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:914)

Answer 1

异常非常清楚恕我直言：在您的Coordinate班级中，您有多个字段，这些字段映射到同一列generic_fk（我不能说哪个是其他字段，如您所示我们只是课程的一部分）。从您的代码中我知道必须至少有3个，因为genericFk字段已标记为insertable=false, updatable=false。还要确保您的实体类只部署一次。

Hibernate通用外键具有一对多的关系

1 个答案: