`method_missing’：用户的未定义方法`devise’（调用’User.connection’建立连接）
我是Ruby on Rails的新手，我正在努力创建我的第一个应用程序。 我运行任何rails generate命令时都遇到问题。 我收到以下错误
MyUsers-MacBook-Pro:MyApp MyUser$ rails generate devise:install Warning: Running `gem pristine --all` to regenerate your installed gemspecs (and deleting then reinstalling your bundle if you use bundle --path) will improve the startup performance of Spring. /Users/MyUser/.gem/ruby/2.0.0/gems/activerecord-4.1.2.rc1/lib/active_record/dynamic_matchers.rb:26:in `method_missing': undefined method `devise' for User (call 'User.connection' to establish a connection):Class (NoMethodError) from /Users/MyUser/.Trash/MyApp/app/models/user.rb:4:in `' from /Users/MyUser/.Trash/MyApp/app/models/user.rb:1:in `' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:443:in `load' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:443:in `block in load_file' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:633:in `new_constants_in' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:442:in `load_file' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:342:in `require_or_load' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:480:in `load_missing_constant' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:180:in `const_missing' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/inflector/methods.rb:238:in `const_get' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/inflector/methods.rb:238:in `block in constantize' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/inflector/methods.rb:236:in `each' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/inflector/methods.rb:236:in `inject' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/inflector/methods.rb:236:in `constantize' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:552:in `get' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:583:in `constantize' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise.rb:297:in `get' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise/mapping.rb:77:in `to' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise/mapping.rb:72:in `modules' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise/mapping.rb:89:in `routes' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise/mapping.rb:156:in `default_used_route' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise/mapping.rb:66:in `initialize' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise.rb:331:in `new' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise.rb:331:in `add_mapping' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise/rails/routes.rb:221:in `block in devise_for' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise/rails/routes.rb:220:in `each' from /Library/Ruby/Gems/2.0.0/gems/devise-3.2.4/lib/devise/rails/routes.rb:220:in `devise_for' from /Users/MyUser/.Trash/MyApp/config/routes.rb:2:in `block in ' from /Users/MyUser/.gem/ruby/2.0.0/gems/actionpack-4.1.2.rc1/lib/action_dispatch/routing/route_set.rb:337:in `instance_exec' from /Users/MyUser/.gem/ruby/2.0.0/gems/actionpack-4.1.2.rc1/lib/action_dispatch/routing/route_set.rb:337:in `eval_block' from /Users/MyUser/.gem/ruby/2.0.0/gems/actionpack-4.1.2.rc1/lib/action_dispatch/routing/route_set.rb:315:in `draw' from /Users/MyUser/.Trash/MyApp/config/routes.rb:1:in `' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:241:in `load' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:241:in `block in load' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:232:in `load_dependency' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:241:in `load' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application/routes_reloader.rb:40:in `block in load_paths' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application/routes_reloader.rb:40:in `each' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application/routes_reloader.rb:40:in `load_paths' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application/routes_reloader.rb:16:in `reload!' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application/routes_reloader.rb:26:in `block in updater' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/file_update_checker.rb:75:in `call' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/file_update_checker.rb:75:in `execute' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application/routes_reloader.rb:27:in `updater' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application/routes_reloader.rb:7:in `execute_if_updated' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application/finisher.rb:71:in `block in ' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/initializable.rb:30:in `instance_exec' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/initializable.rb:30:in `run' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/initializable.rb:55:in `block in run_initializers' from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:150:in `block in tsort_each' from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:183:in `block (2 levels) in each_strongly_connected_component' from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:219:in `each_strongly_connected_component_from' from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:182:in `block in each_strongly_connected_component' from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:180:in `each' from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:180:in `each_strongly_connected_component' from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tsort.rb:148:in `tsort_each' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/initializable.rb:54:in `run_initializers' from /Users/MyUser/.gem/ruby/2.0.0/gems/railties-4.1.2.rc1/lib/rails/application.rb:300:in `initialize!' from /Users/MyUser/.Trash/MyApp/config/environment.rb:5:in `' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:247:in `require' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:247:in `block in require' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:232:in `load_dependency' from /Users/MyUser/.gem/ruby/2.0.0/gems/activesupport-4.1.2.rc1/lib/active_support/dependencies.rb:247:in `require' from /Library/Ruby/Gems/2.0.0/gems/spring-1.1.3/lib/spring/application.rb:92:in `preload' from /Library/Ruby/Gems/2.0.0/gems/spring-1.1.3/lib/spring/application.rb:140:in `serve' from /Library/Ruby/Gems/2.0.0/gems/spring-1.1.3/lib/spring/application.rb:128:in `block in run' from /Library/Ruby/Gems/2.0.0/gems/spring-1.1.3/lib/spring/application.rb:122:in `loop' from /Library/Ruby/Gems/2.0.0/gems/spring-1.1.3/lib/spring/application.rb:122:in `run' from /Library/Ruby/Gems/2.0.0/gems/spring-1.1.3/lib/spring/application/boot.rb:18:in `' from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from /Library/Ruby/Site/2.0.0/rubygems/core_ext/kernel_require.rb:55:in `require' from -e:1:in `'
即使我没有将gem’devise gem 'devise'添加到我的Gemfile中，我仍然会收到该错误。 我甚至创建了一个新的应用程序并得到了该错误。
我甚至在用户的未定义方法’devise’中尝试了答案
知道我怎么能摆脱这个错误？
编辑我目前没有任何型号 
发生这种情况是因为您错过了命令：
rails generate devise:install
您只需要暂时（在routes.rb / user.rb中）对所有设计线进行注释即可获得加注。
并再次运行命令。
这是合适的订单。
gem 'devise' Run the bundle command to install it. rails generate devise:install rails generate devise MODEL
这里模型是在“rails generate devise：install”之前创建的。所以你必须回复一下模型创建的所有内容：
class User < ActiveRecord::Base # Include default devise modules. Others available are: # :confirmable, :lockable, :timeoutable and :omniauthable #devise :database_authenticatable, :registerable, #:recoverable, :rememberable, :trackable, :validatable end
还有这个
Rails.application.routes.draw do #devise_for :users end
现在，运行“rails generate devise：install”，之后取消注释以上内容。
我遇到了一个类似的问题，现有项目刚刚从回购中检出：
具体丢失的文件是：
config/initializers/devise.rb config/locales/devise.en.yml
在这种情况下，因为devise.rb位于.gitignore列表中，所以可以复制config/initializers/devise.rb.example文件。
或者，像我一样，添加：
gem 'devise'
到Gemfile，并运行：
$ bundle install
你忘了用Ctrl C 重新启动服务器 ，并且：
$ rails s
这是一个有点奇怪的问题，我也碰到了！ 尝试在app / models / install.rb文件中添加extend Devise::Models ，如下面的链接所述。
希望这可以帮助！ https://github.com/plataformatec/devise/issues/3877
rails g devise install ！= rails g devise:install
我也遇到了这个问题。 执行rails generate devise install （原文如此！）没有什么似乎没有工作。 终端输出是：
$ rails g devise install Running via Spring preloader in process 5422 invoke active_record create db/migrate/20180306165306_devise_create_installs.rb create app/models/install.rb insert app/models/install.rb route devise_for :installs
但我错过了分号 。 恢复这些更改，然后执行rails generate devise:install （注意: devise和install之间），一切都很完美。 您还可以获得更广泛的输出：
$ rails g devise:install Running via Spring preloader in process 5218 create config/initializers/devise.rb create config/locales/devise.en.yml =============================================================================== Some setup you must do manually if you haven't yet: 1. Ensure you have defined default url options in your environments files. Here is an example of default_url_options appropriate for a development environment in config/environments/development.rb: config.action_mailer.default_url_options = { host: 'localhost', port: 3000 } In production, :host should be set to the actual host of your application. 2. Ensure you have defined root_url to *something* in your config/routes.rb. For example: root to: "home#index" 3. Ensure you have flash messages in app/views/layouts/application.html.erb. For example: <%= notice %>
<%= alert %>
4. You can copy Devise views (for customization) to your app by running: rails g devise:views ===============================================================================