优雅地处理关联上的 NoMethodError

Question

什么是处理NoMethodError 关联的好方法？

例如，假设我点击了一个类似 http://mysite.com/orders/ID_THAT_DOESNT_EXISTS/payments 的 URL，我会收到一个异常，抱怨 #payments 被 nil 调用。

理想情况下，我会收到一条快速消息，轻轻地通知用户具有上述 ID 的订单不存在。

更好的是，我希望将这一点推广到所有其他模型。

这是OrdersController 的示例：

module Spree
  module Admin
    class OrdersController < Spree::Admin::BaseController
      require 'spree/core/gateway_error'
      before_filter :initialize_txn_partials
      before_filter :initialize_order_events
      before_filter :load_order, :only => [:show, :edit, :update, :fire, :resend, :history, :user]

      respond_to :html

      def index
        params[:q] ||= {}
        params[:q][:completed_at_not_null] ||= '1' if Spree::Config[:show_only_complete_orders_by_default]
        @show_only_completed = params[:q][:completed_at_not_null].present?
        params[:q][:s] ||= @show_only_completed ? 'completed_at desc' : 'created_at desc'

        if !params[:q][:created_at_gt].blank?
          params[:q][:created_at_gt] = Time.zone.parse(params[:q][:created_at_gt]).beginning_of_day rescue ""
        end

        if !params[:q][:created_at_lt].blank?
          params[:q][:created_at_lt] = Time.zone.parse(params[:q][:created_at_lt]).end_of_day rescue ""
        end

        if @show_only_completed
          params[:q][:completed_at_gt] = params[:q].delete(:created_at_gt)
          params[:q][:completed_at_lt] = params[:q].delete(:created_at_lt)
        end

        @search = Order.ransack(params[:q])
        @orders = @search.result.includes([:user, :shipments, :payments]).page(params[:page]).per(Spree::Config[:orders_per_page])
        respond_with(@orders)
      end

      def show
        respond_with(@order)
      end

      def new
        @order = Order.create
        respond_with(@order)
      end

      def edit
        respond_with(@order)
      end

      def update
        return_path = nil
        if @order.update_attributes(params[:order]) && @order.line_items.present?
          @order.update!
          unless @order.complete?
            # Jump to next step if order is not complete.
            return_path = admin_order_customer_path(@order)
          else
            # Otherwise, go back to first page since all necessary information has been filled out.
            return_path = admin_order_path(@order)
          end
        else
          @order.errors.add(:line_items, t('errors.messages.blank')) if @order.line_items.empty?
        end

        respond_with(@order) do |format|
          format.html do
            if return_path
              redirect_to return_path
            else
              render :action => :edit
            end
          end
        end
      end


      def fire
        # TODO - possible security check here but right now any admin can before any transition (and the state machine
        # itself will make sure transitions are not applied in the wrong state)
        event = params[:e]
        if @order.send("#{event}")
          flash.notice = t(:order_updated)
        else
          flash[:error] = t(:cannot_perform_operation)
        end
      rescue Spree::Core::GatewayError => ge
        flash[:error] = "#{ge.message}"
      ensure
        respond_with(@order) { |format| format.html { redirect_to :back } }
      end

      def resend
        OrderMailer.confirm_email(@order, true).deliver
        flash.notice = t(:order_email_resent)

        respond_with(@order) { |format| format.html { redirect_to :back } }
      end

      private

      def load_order
        @order ||= Order.find_by_number(params[:id], :include => :adjustments) if params[:id]
        @order
      end

      # Allows extensions to add new forms of payment to provide their own display of transactions
      def initialize_txn_partials
        @txn_partials = []
      end

      # Used for extensions which need to provide their own custom event links on the order details view.
      def initialize_order_events
        @order_events = %w{cancel resume}
      end

    end
  end
end

Answer 1

您还没有提供代码示例来解决问题，但从最基本的意义上说，无论您在哪里查找不存在的订单，设置一条 flash 消息并重定向到某个地方。