JPA级联集内容
你知道为什么会这样吗:JPA级联集内容,jpa,associations,one-to-many,cascade,many-to-one,Jpa,Associations,One To Many,Cascade,Many To One,你知道为什么会这样吗: class Owner { @OneToMany(mappedBy = "owner", cascade = CascadeType.ALL) public Set<Storage> storages ... class Storage { @ManyToOne public Owner owner ... 测试失败: [info] - Storage *** FAILED *** [info] Storage does
class Owner {
@OneToMany(mappedBy = "owner",
cascade = CascadeType.ALL)
public Set<Storage> storages
...
class Storage {
@ManyToOne
public Owner owner
...
测试失败:
[info] - Storage *** FAILED ***
[info] Storage does not have an Owner
如何修复它?这个问题每两天被问一次。JPA使用双向关联的拥有方来了解关联是否存在。拥有方是没有
mappedBy
属性的一方。因此,要告诉JPA所有者和存储之间存在关联,必须设置存储的所有者:
s.setOwner(o);
所有的一切都在哪里重要吗?因为现在,我得到“所有者没有任何存储”…维护对象图的一致性是您的责任。必须初始化关联的双方。如果您只设置了拥有方,关联将被持久化,但Hibernate不会为您初始化另一方。如果在新事务中重新加载对象,JPA将为您填充两侧。在当前事务期间,它将从缓存返回对象,就像您初始化它们一样。
s.setOwner(o);