Question

我在Scala中有以下Hibernate类Group和Items，其中一个Group包含许多Items：

@Entity
@Table(name = "items")
class Item extends Serializable {

    @Id
    @ManyToOne
    @JoinColumn(name="group_sk", nullable=false)
    var group: Group = _

    @Id
    var index: Int = _

    var name: String = _

    def canEqual(a: Any) = a.isInstanceOf[Item]

    override def equals(that: Any): Boolean =
        that match {
            case that: Item => that.canEqual(this) && this.hashCode == that.hashCode
            case _ => false
     }

    override def hashCode: Int = {
        val prime = 31
        var result = 1
        result = prime * result + group.sk;
        result = prime * result + index
        return result
    }

}


@Entity
@Table(name = "groups")
class Group {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "group_generator")
    @SequenceGenerator(name="group_generator", 
    sequenceName = "GroupSeq", allocationSize = 1)    
    var sk: Int = _

    @Column(name = "group_name")
    var name: String = _

    @OneToMany(cascade=Array(CascadeType.ALL))
    @JoinColumn(name="group_sk") 
    var items: java.util.List[Item] = _
}

假设我有第1组和第A项和第B项。要更新组，我让用户编辑项目，所以当我保存组时，我先清除Items数组，然后附加新项目（注意用户可能会留下一些项目，因此这些项目将被删除并重新插入）：

val group = session.get(classOf[Group],groupCode)
session.beginTransaction
group.name = "Group 1x"
group.items.clear
for (i <- updatedItems) {
      val it = new Item 
      it.group = group
      it.index = i.index
      it.name = i.name
      group.itemss.add(it)
}
session.update(group)
session.getTransaction.commit

当我尝试更新时，出现以下错误：

执行异常[[例外：applyReq中的失败：不同具有相同标识符值的对象已与该关联会话： [admin.group.manage.Item#admin.group.manage.Item@50ec]]]

如何解决这个问题？

Answer 1

如果要修改hibernate会话中已存在的对象，则无法创建新对象，设置相同的ID并期望它将更新原始对象。您需要从会话中实际检索原始对象，然后进行修改。

替换

val it = new Item

与

val it = session.get(classOf[Item], i.index)

Hibernate + Scala：删除和重新插入子项时出错

1 个答案: