无法在一对多关系休眠注释中插入空值 [英] cannot insert null in one to many relationship hibernate annotation

问题描述

我有一个类 A{Set b .....} 它将类 B 的引用保存为 Set.这是一对多的关系.这两个类在 oracle 中都有音序器.我将级联放在休眠注释中.当我保存 A 类时，它给了我无法插入 null B.a_id 的错误.A-id 在我的数据库中不可为空.我怎样才能保持这种关系.

I have a class A{Set b .....} which holds references of class B as Set. It is one to many relationship. Both class have sequencer in oracle. I put cascade to all in hibernate annotations. When i save class A, it gives me error that cannot insert null B.a_id . A-id is not nullable in my database. How can i persist this relationship.

推荐答案

这是从 A->B 的单向关系.表 B 中的 a_id 列不可为空.当休眠尝试保存 B 类时，它无法找到 a_id 的值.

This is a unidirectional relationship from A->B. a_id column in table B is not nullable. When hibernate tries to save class B, it not able to find value for a_id.

好吧，您是否尝试使 JoinColumn 不可nullable?

Well, did you try to make the JoinColumn non nullable?

@OneToMany 
@Cascade({CascadeType.ALL}) 
@JoinColumn(name="A_ID", nullable=false)
private Set<B> b;

另见

• Hibernate 核心参考指南
  • 6.2.1.集合外键

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