def custom_value(promotion=nil)
    return nil if promotion.nil?
    if @promotion_custom_point_values.nil? or @current_promotion != promotion
      Rails.cache.fetch("custom_value_#{promotion.id}", :expires_in => 5.minutes, :race_condition_ttl => 10) do
        @promotion_custom_point_values = promotion.custom_point_values.reduce({}) do |hash, value|
          hash[value.action_id] = value if !hash.has_key?(value.action_id)
          hash
        end
      end
    end
    @current_promotion = promotion
    @promotion_custom_point_values[self.id]
  end