为什么我在运行webrick服务器时会得到未初始化的常量设计名称错误？
在我的应用程序中，我使用了ruby 1.9.2和rails 3.0.3并且还安装了Devise gem。问题在我运行Webrick服务器时开始我得到未初始化的常量设计名称错误。
/home/app/Workspace/project/Library_Management/Library_Management/config/initializers/devise.rb:3:in `': uninitialized constant Devise (NameError) from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/engine.rb:201:in `block (2 levels) in ' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/engine.rb:200:in `each' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/engine.rb:200:in `block in ' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/initializable.rb:25:in `instance_exec' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/initializable.rb:25:in `run' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/initializable.rb:50:in `block in run_initializers' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/initializable.rb:49:in `each' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/initializable.rb:49:in `run_initializers' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/application.rb:134:in `initialize!' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/application.rb:77:in `method_missing' from /home/app/Workspace/project/Library_Management/Library_Management/config/environment.rb:5:in `' from /home/app/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:54:in `require' from /home/app/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:54:in `require' from /home/app/Workspace/project/Library_Management/Library_Management/config.ru:3:in `block in ' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/rack-1.2.3/lib/rack/builder.rb:46:in `instance_eval' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/rack-1.2.3/lib/rack/builder.rb:46:in `initialize' from /home/app/Workspace/project/Library_Management/Library_Management/config.ru:1:in `new' from /home/app/Workspace/project/Library_Management/Library_Management/config.ru:1:in `' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/rack-1.2.3/lib/rack/builder.rb:35:in `eval' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/rack-1.2.3/lib/rack/builder.rb:35:in `parse_file' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/rack-1.2.3/lib/rack/server.rb:162:in `app' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/rack-1.2.3/lib/rack/server.rb:253:in `wrapped_app' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/rack-1.2.3/lib/rack/server.rb:204:in `start' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/commands/server.rb:65:in `start' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/commands.rb:30:in `block in ' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/commands.rb:27:in `tap' from /home/app/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.9/lib/rails/commands.rb:27:in `' from /home/app/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:58:in `require' from /home/app/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:58:in `rescue in require' from /home/app/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:35:in `require' 谢谢
检查你的config / application.rb，你需要添加require’devise’，你应该没问题。
如果您正在编写具有自己的设备配置的引擎，请添加
require 'devise'
在设计初始化器的开头。 在我的情况下，我在应用程序中没有设计要求:)
干杯
确保您已在Gemfile中列出Devise并运行bundle install 。
当我有一个自定义设计控制器覆盖’新’方法来做一些自定义的东西，并忘了使用’超’时，我得到了一个错误
你有自定义控制器吗？
我有一个类似的问题，我发现这个https://github.com/plataformatec/devise
它说你必须做
rails generate devise:install
在该页面上的“入门”后，我开始了
如果你不再使用设计gem，那么删除
gem 'devise'
来自gemfile和删除
config/initializers/devise.rb
还要确保设备没有在任何地方使用
我只是遇到了这个问题，这是因为我错误地生成了一个视图模型而且我没有从routes.rb中删除它
我不得不在spec / spec_helper.rb文件中添加require’devise require 'devise' ，并且该错误消失了。
我在安装Devise之后添加了几列，并在我的用户模型中添加了一些validation。 从错误消息，它看起来像铁路找不到必要的库因此它找不到Devise。 也许签出Github设计Wiki页面并确保所有依赖项都满意？
希望能帮助到你！
在你的config / application.rb中添加require 'yaml' 。 这个对我有用。 尝试