问题
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 !!
回答1:
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?
来源：https://stackoverflow.com/questions/16855838/cascade-delete-with-many-to-many-mapping-in-grails