在Grails中使用多对多映射级联删除 [英] cascade delete with many-to-many mapping in Grails

问题描述

我有多对多映射的问题。

[案例]

• 帐户拥有社区（所有者）


• 社区有许多帐户（成员）

当我删除社区的实例时，所有者帐户也被删除。

我不希望所有者帐户被移除。

我的映射是错误的？

[域类]

  class Account {
 
字符串名称
 
 static hasMany = [communities：Community] 
 static belongsTo = [Community] 
} 
 
 class社区{
 
字符串名称
帐户所有者
 
 static hasMany = [会员：帐户] 
} 
  

[TestCode]

  def admin = new Account（name：'admin'）。save（flush：true）
 def user = new Account（name：'user'）。save（flush：true）
 
 def c = new Community（name：'TestCommunity'）
 
 c.owner = admin 
 
 c.add ToMembers（admin）
 c.addToMembers（user）
 c.save（flush：true）
 
 c.removeFromMembers（user）
 c.save（flush： true）
 
 c.delete（flush：true）
  

$ p $ Hibernate：insert into account（id，version，name）values（null，？，？）
Hibernate ：插入到社区（id，版本，名称，owner_id）值（空，？，？，？）
休眠：更新帐户设置版本= ?,名称=？其中id =？和版本=？
Hibernate：插入到community_members（community_id，account_id）值（？，？）
Hibernate：更新帐户集版本=？，name =？其中id =？和版本=？
Hibernate：更新社区设置版本=？，名称=？，owner_id =？其中id =？和版本=？
Hibernate：从community_members删除community_id =？和account_id =？
Hibernate：从community_members删除community_id =？
Hibernate：从社区中删除id =？和版本=？
Hibernate：从账户中删除id =？和版本=？ < ==不是预期的！


解决方案

您必须提供相当于 on delete set mapping

已经有一个关于它的问题。请参阅它进一步的细节如何覆盖Grails GORM中关系的级联删除？

I have problem about many-to-many mapping.

[Case]

• Account owns Community(owner)
• Community has many Account(members)

When I delete instance of Community, owner account is also delete.

I don't expect owner account to be removed.

My mapping is wrong?

[Domain Class]

class Account {

String name

static hasMany = [communities: Community]
static belongsTo = [Community]
}

class Community {

String name
Account owner

static hasMany = [members: Account]
}

[TestCode]

def admin = new Account(name: 'admin').save(flush:true)
def user = new Account(name: 'user').save(flush:true)

def c = new Community(name: 'TestCommunity')

c.owner = admin

c.addToMembers(admin)
c.addToMembers(user)            
c.save(flush:true)

c.removeFromMembers(user)
c.save(flush:true)

c.delete(flush:true)

[Hibernate Log]

Hibernate: insert into account (id, version, name) values (null, ?, ?)
Hibernate: insert into community (id, version, name, owner_id) values (null, ?, ?, ?)
Hibernate: update account set version=?, name=? where id=? and version=?
Hibernate: insert into community_members (community_id, account_id) values (?, ?)
Hibernate: update account set version=?, name=? where id=? and version=?
Hibernate: update community set version=?, name=?, owner_id=? where id=? and version=?
Hibernate: delete from community_members where community_id=? and account_id=?
Hibernate: delete from community_members where community_id=?
Hibernate: delete from community where id=? and version=?
Hibernate: delete from account where id=? and version=?          <== not expected !!

解决方案

You have to provide hibernate equivalent to on delete set null mapping

There is already a question about it. Please refer to it for further details How do I override the cascade delete for a relation in Grails GORM?

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