gistfile1.rb

  def async_save
    json_v2_response_only do
      json = JSON.parse(params[:promotion])
      @promotion = current_user.promotions_find(json["id"])
      validator = PromotionModuleValidator.new(@promotion, json)

      if validator.valid?
        @promotion.update_from_json(json, true)

        # Update the mailing for the RSS Promotion when changing the promotion's name
        if @promotion.rss_promotion.present? && @promotion.rss_promotion.mailing.present?
          @promotion.rss_promotion.mailing.update_attribute :subject, @promotion.name
        end

        # Add the promotion to the promotions the user has selected on the dashboard
        current_user.add_selected_promotion @promotion.id if current_user.selected_promotions.size > 0

        PromotionPresenter.new(@promotion).to_hash(:composer)
      else
        raise StandardError, h(validator.errors.to_sentence)
      end
    end
  end



class PromotionModuleValidator

  attr_reader :promotion, :json

  def initialize(promotion, json)
    @promotion = promotion
    @json = json
  end

  def valid?
    errors.blank?
  end

  def errors
    @errors ||= determine_errors
  end

  private

  def determine_errors
    problems = []
    modules = promotion.promotion_modules.all

    json["modules"].each_with_index do |module_json, position|
      promotion_module = modules.detect { |m| m.id == module_json["id"] }
      if promotion_module
        promotion_module.update_from_json(module_json, position)
      else
        promotion_module = promotion_modules.create_from_json(module_json, position)
      end

      problems << promotion_module.errors.full_messages.to_sentence unless promotion_module.valid?
    end

    problems
  end

end