RoR: Destroy association with has_many, :through if orphaned

Question

Given Ryan Bates's great tutorial on Virtual Attributes, how would I go about destroying a Tag (not Tagging) if, once the article is destroyed, that Tag is no longer used?

I tried doing something like this:

class Article < ActiveRecord::Base
   ...
   after_destroy :remove_orphaned_tags

   private

   def remove_orphaned_tags
     tags.each do |tag|
       tag.destroy if tag.articles.empty?
     end
   end
end

... but that doesn't seem to work (the tags still exist after the article is deleted, even though no other article uses them). What should I be doing to accomplish this?

Answer 1

In your remove_orphaned_tags method, what is "tags" that you do an each on?

Wouldn't you need like Tag.all ?

Answer 2

JRL is correct. Here is the proper code.

 class Article < ActiveRecord::Base
    ...
    after_destroy :remove_orphaned_tags

    private
    def remove_orphaned_tags
      Tag.find(:all).each do |tag|
        tag.destroy if tag.articles.empty?
      end
    end
 end

Answer 3

i know it's way too late, but for people who encounter the same issue, this is my solution:

 class Article < ActiveRecord::Base
    ...
    around_destroy :remove_orphaned_tags

    private

    def remove_orphaned_tags
        ActiveRecord::Base.transaction do
          tags = self.tags # get the tags
          yield # destroy the article
          tags.each do |tag| # destroy orphan tags
            tag.destroy if tag.articles.empty?
          end
        end
    end

 end