ruby-on-rails - Rails :dependent => 有条件的销毁

Question

假设我有狗，皮带和主人......如果我破坏皮带，我也想摧毁狗......但如果狗有主人......

Answer 1

您不想在:dependent => :destroy这里使用，而是before_destroy像这样使用回调：

#leash.rb

before_destroy :destroy_dog

def destroy_dog
  dog.destroy unless dog.owner
end

Answer 2

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

也适用has_many，它根据where条件破坏对象