promotions_controller.rb

module Spree
  module Api
    class PromotionsController < Spree::Api::BaseController
      before_action :requires_admin
      before_action :load_promotion

      def show
        if @promotion
          respond_with(@promotion, default_template: :show)
        else
          raise ActiveRecord::RecordNotFound
        end
      end

      private

      def requires_admin
        return if @current_user_roles.include?("admin")
        unauthorized && return
      end

      def load_promotion
        @promotion = Spree::Promotion.find_by(id: params[:id]) || Spree::Promotion.with_coupon_code(params[:id])
      end
    end
  end
end