Products Controller with sort by price

products_controller_decorator_with_sorting.rb

module Spree
  ProductsController.class_eval do
    helper_method :sorting_param
    alias_method :old_index, :index

    def index
      old_index # Like calling super: http://stackoverflow.com/a/13806783/73673
      @products = @products.includes(:prices).send(sorting_scope)
    end

    def sorting_param
      params[:sorting].try(:to_sym) || default_sorting
    end

    private

    def sorting_scope
      allowed_sortings.include?(sorting_param) ? sorting_param : default_sorting
    end

    def default_sorting
      :ascend_by_updated_at
    end

    def allowed_sortings
      [:descend_by_master_price, :ascend_by_master_price, :ascend_by_updated_at]
    end
  end
end