GORM关系没有依赖删除 [英] GORM Relations without dependent delete
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问题描述
我有两个域类User和Node。以下条件应成立。
- a用户可以有零个或一个节点
- 节点可以有一个到n用户它始终使用User实例进行初始化)
- 如果删除节点,用户将不会被删除
- 如果删除用户,该节点将被删除
我试过了:
class User {
Node节点
}
类节点{
//构造函数
节点(用户用户) {
addToUsers(用户)
save()
}
hasMany = [用户:用户]
}
前者不起作用。它不起作用,因为当你删除一个节点时,用户实例中有一个依赖的引用不会自动删除。
我如何建模域在这种情况下使用连接表?
$
解决方案
b $ b
class User {
Set< Node> getNodes(){
UserNode.executeQuery(从UserNode x中选择x.node,其中x.user =:user,[user:this])
}
def addToNodes (节点节点){
def userNode = new UserNode()
userNode.user = this
userNode.node = node
userNode.save()
}
}
class Node {
Set< User> getUsers(){...}
}
class UserNode {
用户用户
节点节点
}
I have two domain classes User and Node. The following conditions should hold.
- a User can have zero or one node
- a Node can have one to n User (it is always initialized with a User instance)
- if you delete a Node the User will not be deleted
- if you delete a User the reference in the Node will be deleted
I tried:
class User {
Node node
}
class Node {
// constructor
Node(User user) {
addToUsers(user)
save()
}
hasMany = [users: User]
}
The former does not work. It does not work because when you delete a node there is a dependent reference in the user instance that will not be delete automatically.
How can I model the domain classes in this case?
解决方案
Use a join table like this:
class User {
Set<Node> getNodes() {
UserNode.executeQuery("select x.node from UserNode x where x.user = :user", [user: this])
}
def addToNodes(Node node) {
def userNode = new UserNode()
userNode.user = this
userNode.node = node
userNode.save()
}
}
class Node {
Set<User> getUsers() { ... }
}
class UserNode {
User user
Node node
}
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