使用 JPA 注释自动从父项中删除子项和从子项中自动删除父项 [英] Delete child from parent and parent from child automatically with JPA annotations

问题描述

假设我们有 3 个实体对象类:

Suppose that we have 3 Entities object class:

class Parent {
    String name;
    List<Child> children;
}

class Child {
    String name;
    Parent parent;
}

class Toy {
    String name;
    Child child;
}

我如何使用 JPA2.x(或休眠)注释来:

How can I use JPA2.x (or hibernate) annotations to:

1. 父删除时自动删除所有子项(一对多)
2. 删除子项时自动从子项列表中删除子项(多对一)
3. 当孩子移除时自动删除玩具(一对一)

我使用的是 Hibernate 4.3.5 和 mysql 5.1.30.

I'm using Hibernate 4.3.5 and mysql 5.1.30.

谢谢

推荐答案

remove 实体状态转换应该从父级到子级级联，而不是相反.

The remove entity state transition should cascade from parent to children, not the other way around.

你需要这样的东西:

class Parent {

    String name;

    @OneToMany(mappedBy = "parent", fetch = FetchType.LAZY, cascade = CascadeType.ALL, orphanRemoval = true)
    List<Child> children = new ArrayList<>();

    public void addChild(Child child) {
        child.setParent(this);
        children.add(child);
    }

    public void removeChild(Child child) {
        children.remove(child);
        child.setParent(null);
    }
}

class Child {

    String name;

    @ManyToOne
    Parent parent;
    
    @OneToOne(mappedBy = "child", cascade = CascadeType.ALL, orphanRemoval = true)
    Toy toy;
}

class Toy {
    String name;

    @OneToOne
    Child child;
}

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