Rails: how to disable before_destroy callback when it's being destroyed because of the parent is being destroyed (:dependent => :destroy)

Question

I have two classes: Parent and Child with

Child:

belongs_to :parent

and

Parent

has_many :children, :dependent          


        

Answer 1

In Rails 4 you can do the following:

class Parent < AR::Base
  has_many :children, dependent: :destroy
end

class Child < AR::Base
  belongs_to :parent

  before_destroy :check_destroy_allowed, unless: :destroyed_by_association

  private

  def check_destroy_allowed
    # some condition that returns true or false
  end
end

This way, when calling destroy directly on a child, the check_destroy_allowed callback will be run, but when you call destroy on the parent, it won't.