gistfile1.rb

module CachedAttributes
  #
  # CachedAttributes creates convenience class methods to save DB query
  # Retailer.allow_alcohol?(1) == Retailer.find(1).allow_alcohol
  #
  # class Retailer
  #   include CachedAttributes
  #   cache_boolean :allow_alcohol
  # end
  #
  def cache_boolean(attribute)
    define_singleton_method("#{attribute}?") do |object_id|
      Rails.cache.fetch("cache-boolean:#{self.name.downcase}-#{object_id}-#{attribute}", expires_in: 1.week, race_condition_ttl: 10) do
        self.find(object_id).send("#{attribute}?")
      end
    end

    define_method("clear_#{attribute}_cache") do
      Rails.cache.delete("cache-boolean:#{self.class.name.downcase}-#{self.id}-#{attribute}")
    end

    after_save "clear_#{attribute}_cache", if: :"#{attribute}_changed?"
  end
end