# The Tagging join model. This model is automatically generated and added to your app if you run the tagging generator included with has_many_polymorphs. class Tagging < ActiveRecord::Base belongs_to :tag belongs_to :taggable, :polymorphic => true # This callback makes sure that an orphaned Tag is deleted if it no longer tags anything. def after_destroy tag.destroy_without_callbacks if tag and tag.taggings.count == 0 end end