How can a Domain Class cascade 'all-delete-orphan' to a child it has no reference to?

In Grails you can have a child class:

class Child {
    Father father
    static belongsTo = [Father, Mother]
}

With two parent classes

class Mother{
}

class Father { 
}

It appears that if I father.delete(), then Grails throws a database error saying that the Father can't be deleted because 开发者_运维知识库the child is still around.

How do I cascade all-delete-orphan the Child if the Father class doesn't have a direct reference to the Child class?

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Make it bi-directional using hasMany.

class Mother{
  static hasMany = Child
}
class Father{
  static hasMany = Child
}

Doing this should make the cascading work such that when you delete one of the parents the child will also be deleted.

---

Peter Ledbrook has a good article that covered this GORM Gotchas Part 2

I couldn't get the belongsTo only part to work, but this works for me:

class Father {
  static hasMany = [children: Child]
}

class Child {
  static belongsTo = [father: Father]
}

void testDeleteItg() {
    def father = new Father().save()
    def child = new Child()
    father.addToChildren child
    child.save()
    def childId = child.id

    father.delete(flush:true)
    assertNull(Child.get(childId))
}