Rails :dependent => destroy with conditions

Question

Say I have dogs, leashes, and owners... If I destroy a leash I want to destroy the dog too.. but not if the dog has an owner..

You can use a callback after_destroy for that. See [this answer][1] for details. [1]: http://stackoverflow.com/questions/6049806/rails-aciverecord-use-dependent-destroy-on-condition — davidrac, Mar 27 '13 at 09:09
I didn't try it myself, but I think you can. The model object should still exist even after destroy. — davidrac, Mar 27 '13 at 09:23

aguynamedloren · Accepted Answer · 2017-01-19T01:59:11.457

4

You don't want to use :dependent => :destroy here, but rather the before_destroy callback like so:

#leash.rb

before_destroy :destroy_dog

def destroy_dog
  dog.destroy unless dog.owner
end

edited Jan 19 '17 at 01:59

answered Mar 27 '13 at 09:12

aguynamedloren

I was thinking something like self.dog.destroy unless self.dog.owner – Abram Mar 27 '13 at 09:18
...but not sure if you can call self after_destroy – Abram Mar 27 '13 at 09:18
yep, before_destroy maybe more appropriate here. updated answer accordingly. – aguynamedloren Mar 27 '13 at 09:24
Hey I think you need to put self.dog.destory unless self.dog.owner no? – Abram Mar 27 '13 at 09:44
`self` is unnecessary here, it is implied. the reason it works is because ruby tries to find a local variable (ie `dog`) and if it doesn't find it, it sends it to `self`. try it and see :) – aguynamedloren Mar 27 '13 at 09:50

score 0 · Answer 2 · answered Jul 04 '18 at 21:52

0

class Book < ApplicationRecord
  belongs_to :author, -> { where active: true },
                        dependent: :destroy
end

works for has_many too, in which it destroys the objects according to the where condition

answered Jul 04 '18 at 21:52

Rodrigo de Sá

2 Answers2