rails sの結果ActionController::RoutingError (uninitialized constant StaticPagesController)」と返ってくる

Question

Ruby on Rails 初心者です。
Railsチュートリアルに沿ってローカル環境でアプリ開発を進めています。
（Railsチュートリアル　https://railstutorial.jp/）
静的なページを生成するために、以下のようにgenerateスクリプトを使いました。

$ rails generate controller StaticPages home help

その結果、routesファイルにはそれぞれのアクションで使われるルールがしっかり定義されました。

【config/routes.rbの中身】
Rails.application.routes.draw do
  get  'static_pages/home'
  get  'static_pages/help'
  root 'application#hello'
end

$ rails sを実行し、試しに
http://localhost:3000/static_pages/homeにアクセスしてみましたが、
このような画面になってしまいます。

rails sを実行した結果

ターミナルには以下のようなエラーメッセージが返ってきています。

/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/2.7.0/fileutils.rb:105: warning: already initialized constant FileUtils::VERSION
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/fileutils-1.5.0/lib/fileutils.rb:105: warning: previous definition of VERSION was here
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/2.7.0/fileutils.rb:1284: warning: already initialized constant FileUtils::Entry_::S_IF_DOOR
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/fileutils-1.5.0/lib/fileutils.rb:1284: warning: previous definition of S_IF_DOOR was here
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/2.7.0/fileutils.rb:1569: warning: already initialized constant FileUtils::Entry_::DIRECTORY_TERM
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/fileutils-1.5.0/lib/fileutils.rb:1577: warning: previous definition of DIRECTORY_TERM was here
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/2.7.0/fileutils.rb:1627: warning: already initialized constant FileUtils::OPT_TABLE
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/fileutils-1.5.0/lib/fileutils.rb:1635: warning: previous definition of OPT_TABLE was here
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/2.7.0/fileutils.rb:1686: warning: already initialized constant FileUtils::LOW_METHODS
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/fileutils-1.5.0/lib/fileutils.rb:1694: warning: previous definition of LOW_METHODS was here
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/2.7.0/fileutils.rb:1693: warning: already initialized constant FileUtils::METHODS
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/fileutils-1.5.0/lib/fileutils.rb:1701: warning: previous definition of METHODS was here
/Users/asamitakaoka/.rbenv/versions/2.7.2/lib/ruby/2.7.0/x86_64-darwin19/stringio.bundle: warning: already initialized constant StringIO::VERSION
=> Booting Puma
=> Rails 6.0.3 application starting in development 
=> Run `rails server --help` for more startup options
Puma starting in single mode...
* Version 4.3.6 (ruby 2.7.2-p137), codename: Mysterious Traveller
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://127.0.0.1:3000
* Listening on tcp://[::1]:3000
Use Ctrl-C to stop
Started GET "/static_pages/home" for ::1 at 2021-03-30 23:58:56 +0900
   (5.0ms)  SET NAMES utf8,  @@SESSION.sql_mode = CONCAT(CONCAT(@@sql_mode, ',STRICT_ALL_TABLES'), ',NO_AUTO_VALUE_ON_ZERO'),  @@SESSION.sql_auto_is_null = 0, @@SESSION.wait_timeout = 2147483
  
ActionController::RoutingError (uninitialized constant StaticPagesController):
  
actionpack (6.0.3) lib/action_dispatch/http/request.rb:92:in `rescue in controller_class_for'
actionpack (6.0.3) lib/action_dispatch/http/request.rb:88:in `controller_class_for'
actionpack (6.0.3) lib/action_dispatch/http/request.rb:81:in `controller_class'
actionpack (6.0.3) lib/action_dispatch/routing/route_set.rb:44:in `controller'
actionpack (6.0.3) lib/action_dispatch/routing/route_set.rb:31:in `serve'
actionpack (6.0.3) lib/action_dispatch/journey/router.rb:49:in `block in serve'
actionpack (6.0.3) lib/action_dispatch/journey/router.rb:32:in `each'
actionpack (6.0.3) lib/action_dispatch/journey/router.rb:32:in `serve'
actionpack (6.0.3) lib/action_dispatch/routing/route_set.rb:834:in `call'
rack (2.2.3) lib/rack/tempfile_reaper.rb:15:in `call'
rack (2.2.3) lib/rack/etag.rb:27:in `call'
rack (2.2.3) lib/rack/conditional_get.rb:27:in `call'
rack (2.2.3) lib/rack/head.rb:12:in `call'
actionpack (6.0.3) lib/action_dispatch/http/content_security_policy.rb:18:in `call'
rack (2.2.3) lib/rack/session/abstract/id.rb:266:in `context'
rack (2.2.3) lib/rack/session/abstract/id.rb:260:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/cookies.rb:648:in `call'
activerecord (6.0.3) lib/active_record/migration.rb:567:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/callbacks.rb:27:in `block in call'
activesupport (6.0.3) lib/active_support/callbacks.rb:101:in `run_callbacks'
actionpack (6.0.3) lib/action_dispatch/middleware/callbacks.rb:26:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/executor.rb:14:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/actionable_exceptions.rb:17:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/debug_exceptions.rb:32:in `call'
web-console (4.0.1) lib/web_console/middleware.rb:132:in `call_app'
web-console (4.0.1) lib/web_console/middleware.rb:28:in `block in call'
web-console (4.0.1) lib/web_console/middleware.rb:17:in `catch'
web-console (4.0.1) lib/web_console/middleware.rb:17:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'
railties (6.0.3) lib/rails/rack/logger.rb:37:in `call_app'
railties (6.0.3) lib/rails/rack/logger.rb:26:in `block in call'
activesupport (6.0.3) lib/active_support/tagged_logging.rb:80:in `block in tagged'
activesupport (6.0.3) lib/active_support/tagged_logging.rb:28:in `tagged'
activesupport (6.0.3) lib/active_support/tagged_logging.rb:80:in `tagged'
railties (6.0.3) lib/rails/rack/logger.rb:26:in `call'
sprockets-rails (3.2.2) lib/sprockets/rails/quiet_assets.rb:13:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/remote_ip.rb:81:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/request_id.rb:27:in `call'
rack (2.2.3) lib/rack/method_override.rb:24:in `call'
rack (2.2.3) lib/rack/runtime.rb:22:in `call'
activesupport (6.0.3) lib/active_support/cache/strategy/local_cache_middleware.rb:29:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/executor.rb:14:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/static.rb:126:in `call'
rack (2.2.3) lib/rack/sendfile.rb:110:in `call'
actionpack (6.0.3) lib/action_dispatch/middleware/host_authorization.rb:82:in `call'
webpacker (4.0.7) lib/webpacker/dev_server_proxy.rb:29:in `perform_request'
rack-proxy (0.6.5) lib/rack/proxy.rb:57:in `call'
railties (6.0.3) lib/rails/engine.rb:527:in `call'
puma (4.3.6) lib/puma/configuration.rb:228:in `call'
puma (4.3.6) lib/puma/server.rb:713:in `handle_request'
puma (4.3.6) lib/puma/server.rb:472:in `process_client'
puma (4.3.6) lib/puma/server.rb:328:in `block in run'
puma (4.3.6) lib/puma/thread_pool.rb:134:in `block in spawn_thread'

ネットで色々と調べてみましたが、
このようなエラーが起きる原因として、
「ファイル名が単数形になってしまっているから」などといった記事しか見つかりませんでした。
私の場合はファイル名も「StaticPages」と複数形になっているので、
おそらくそこは問題ないと思うのですが、、、
どこが問題でエラーが発生しているのでしょうか。

どなたかご教示いただけますと幸いです。

何卒よろしくお願いいたします。

Answer 1

ファイル名も「StaticPages」と複数形になっているので

本当にStaticPagesController.rbというファイルにしたのであれば、正しく動きません。

ファイル名はアンダーバー区切りのstatic_pages_controller.rbとしなければいけません。

Comments

[asm_t]

maisumakun様
ご回答いただきありがとうございます。
返信が遅くなり申し訳ございません。
maisumakun様がおっしゃるとおり、ファイル名をアンダーバー区切りにしたら無事に成功しました！！！
迅速で的確なご回答をいただき本当にありがとうございました...！！