在Rails 4中创建API-未初始化的常量Api :: V1 :: UsersController

对于个人项目，我想在Rails 4中创建一个Restful Web服务。

因此，我使用创建了我的第一个项目rails-api并添加以下代码：

的routes.rb在MyProject的>配置目录

MyProject::Application.routes.draw do
    namespace :api, defaults: {format: 'json'} do
        namespace :v1 do
            resources :users
        end
    end
end

users_controller.rb在MyProject的>应用>控制器> API> V1>用户目录

module Api
    module V1
        class UsersController < ApplicationController
            def index
            end

            def create
            end

            def show
            end

            def update
            end

            def delete
            end
        end 
    end
end

当我使用命令行启动Rails服务器rails s并转到以下URL时：http://localhost:3000/api/v1/users/show我遇到了以下错误：

未初始化的常量Api :: V1 :: UsersController

Rails.root：/ Users / Jean / Development / MyProject

应用程序跟踪| 框架跟踪 完全跟踪activesupport（4.0.4）lib / active_support / inflector / methods.rb：228：inconst_get' activesupport (4.0.4) lib/active_support/inflector/methods.rb:228:in 常量化activeactive（4.0.4）lib / active_support / inflector / methods.rb：224：each' activesupport (4.0.4) lib/active_support/inflector/methods.rb:224:in注入activeactive（4.0。 4）lib / active_support / inflector / methods.rb：224：在constantize' actionpack (4.0.4) lib/action_dispatch/routing/route_set.rb:76:incontroller_reference'动作包（4.0.4）lib / action_dispatch / routing / route_set.rb：66：在controller' actionpack (4.0.4) lib/action_dispatch/routing/route_set.rb:44:in通话中的动作包（4.0.4）lib / action_dispatch / journey / router.rb：71：在block in call' actionpack (4.0.4) lib/action_dispatch/journey/router.rb:59:in每个动作包（4.0.4）中lib / action_dispatch / journey / router.rb：59：在call' actionpack (4.0.4) lib/action_dispatch/routing/route_set.rb:674:in 呼叫机架中（1.5.2）lib / rack / etag.rb：23：在call' rack (1.5.2) lib/rack/conditionalget.rb:25:in呼叫机架中（1.5.2）lib / rack / head.rb：11：call' actionpack (4.0.4) lib/action_dispatch/middleware/params_parser.rb:27:in调用中的activerecord（4.0.4）lib / active_record / query_cache.rb：36：call' activerecord (4.0.4) lib/active_record/connection_adapters/abstract/connection_pool.rb:626:in 调用中的activerecord（4.0.4）lib / active_record / migration。call' actionpack (4.0.4) lib/action_dispatch/middleware/callbacks.rb:29:in在通话的activesupport（4.0.4）中阻止lib / active_support / callbacks.rb：373：在_run__4323212420903942114__call__callbacks' activesupport (4.0.4) lib/active_support/callbacks.rb:80:inrun_callbacks的actionpack中（4.0.4）lib / action_dispatch / middleware / callbacks.rb：27：在call' actionpack (4.0.4) lib/action_dispatch/middleware/reloader.rb:64:in 通话的actionpack（4.0.4） lib / action_dispatch / middleware / remote_ip.rb：76：call' actionpack (4.0.4) lib/action_dispatch/middleware/debug_exceptions.rb:17:in 调用中的动作包（4.0.4）lib / action_dispatch / middleware / show_exceptions.rb：30：在call' railties (4.0.4) lib/rails/rack/logger.rb:38:incall_app的Railties中（4.0.4）lib / rails /机架/记录器。 rb：20：inblock in call' activesupport (4.0.4) lib/active_support/tagged_logging.rb:68:in标记为'activesupport（4.0.4）中的块lib / active_support / tagged_logging.rb：26：intagged' activesupport (4.0.4) lib/active_support/tagged_logging.rb:68:in标记为'railties（4.0.4）lib / rails / rack / logger.rb：20：in call' actionpack (4.0.4) lib/action_dispatch/middleware/request_id.rb:21:incall'机架（1.5.2）lib / rack / runtime.rb：17：call' activesupport (4.0.4) lib/active_support/cache/strategy/local_cache.rb:83:in通话中机架（1.5.2）lib / rack / lock.rb：17：call' actionpack (4.0.4) lib/action_dispatch/middleware/static.rb:64:in通话中的栏杆（4.0.4）lib / rails / engine.rb ：511：在call' railties (4.0.4) lib/rails/application.rb:97:in通话中机架（1.5.2）lib / rack / lock.rb：17：incall' rack (1.5.2) lib/rack/content_length.rb:14:in呼叫'机架（1.5.2）lib / rack / handler / webrick.rb：60：service' /Users/Jean/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver.rb:138:in 服务中'/Users/Jean/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/httpserver .rb：94：run' /Users/Jean/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/webrick/server.rb:295:in 在start_thread块中

我在Stackoverflow上发现了很多帖子，但都出现了相同的错误，但是答案并没有帮助我解决问题。

谢谢 ！