级联的ManyToMany只能以一种方式级联 [英] ManyToMany with cascade all only cascading one way

问题描述

我有2个实体: 1)用户 2)部门.

I have 2 entities: 1) User 2) Department.

每个都包含另一个SET，因为它们之间的关系是manyToMany，

each contains a SET of the other since the relationship between them is manyToMany,

我在用户实体和部门实体上以及当我这样做时都标记了(CascadeType.ALL):

I marked (CascadeType.ALL) on the user entity and the department entity and when i do :

userX.getDepartments.remove(departmentX);
save(userX);

它的工作原理与预期的一样-实际上暗示着

it works like intended - it actually implies that

departmentX.getUsers.contains(userX) == false.

被隐式调用.

但是，当我这样做

departmentY.getUsers.remove(userX);
save(departmentY); 

它没有级联！ 含义-我可以做到

it doesn't cascade! meaning - i can do

userX.getDepartments.contains(departmentY) == true 

有什么想法为什么级联都只能以一种方式起作用? 有解决办法吗?

any ideas why the cascade all works only one way? is there a solution?

谢谢

推荐答案

级联与您正在执行的操作无关.级联的意思是:当我保存X时，也保存Y.

The cascade is irrelevant to what you're doing. Cascading means: when I save X, also save Y.

您有一个ManyToMany双向关联.关联的所有者是用户.这意味着对User.departments集合的每次更改都将保存到数据库中.另一面(Department.users)是反面.这意味着Hibernate将忽略对Department.users的所有更改.

You have a ManyToMany bidirectional association. The owner side of the asociation is User. This means that every change to the User.departments collection will be saved into the database. The other side (Department.users) is the inverse side. This means that every change to Department.users will be ignored by Hibernate.

您有责任在所有者端执行操作，并且最好将关联双方保持一致状态:将用户从部门中撤离时，部门也应从用户中撤离，并且反之亦然. Hibernate并不在乎双方是否处于一致状态:它保留了关联的所有者方(没有mappedBy属性的那一方)的状态

It's YOUR responsibility to xecute the operations in the owner side and, preferrably, to maintain both sides of the association in a coherent state: when a user is removed from a department, the department should also be removed from the user, and vice-versa. Hibernate doesn't care if both sides are in a coherent state though: it persists the state of the owner side of the association (the one which doesn't have a mappedBy attribute)

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