我正在尝试跟随 Railscasts #235（rails 应用程序中的 Omniauth）。
Rails (v3.2) 中的 Omniauth gem 遇到一些问题。当我在我的 Gemfile 中安装 gem 时，并在 omniauth.rb 中指定以下内容（在 config/initializers/ 中）：
Rails.application.config.middleware.use OmniAuth::Builder do
provider :twitter, '...', '...'
end
我似乎无法启动我的服务器 - 我收到以下错误：
/Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/omniauth-1.1.0/lib/omniauth/builder.rb:38:in `rescue in provider': Could not find matching strategy for :twitter. You may need to install an additional gem (such as omniauth-twitter). (LoadError)
我可以包含omniauth-twitter gem（服务器以它开头），但我不知道为什么没有它就行不通。当我为 railscast 分叉存储库时，一切正常，所以不知道为什么会这样。我认为这是因为我安装了omniauth-twitter gem（虽然没有在捆绑包中使用），但我卸载了它，但没有奏效。
完整的宝石文件：
source 'https://rubygems.org'
gem 'rails', '3.2.2'
gem 'omniauth'
gem 'jquery-rails'
gem 'bootstrap-sass'
gem 'bcrypt-ruby'
gem 'redcarpet'
group :development, :test do
gem 'pg', '0.12.2'
gem 'rspec-rails', '2.9.0'
gem 'annotate'
end
group :assets do
gem 'sass-rails', '~> 3.2.3'
gem 'coffee-rails', '~> 3.2.1'
gem 'uglifier', '>= 1.0.3'
end
group :test do
gem 'capybara', '1.1.2'
gem 'factory_girl_rails', '1.4.0'
end
group :production do
gem 'pg', '0.12.2'
end
下面的完整堆栈跟踪：
/Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/omniauth-1.1.0/lib/omniauth/builder.rb:38:in `rescue in provider': Could not find matching strategy for :twitter. You may need to install an additional gem (such as omniauth-twitter). (LoadError)
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/omniauth-1.1.0/lib/omniauth/builder.rb:35:in `provider'
from /Users/tarunsachdeva/Development/rails/workbench/config/initializers/omniauth.rb:2:in `block in <top (required)>'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/builder.rb:51:in `instance_eval'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/builder.rb:51:in `initialize'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/omniauth-1.1.0/lib/omniauth/builder.rb:7:in `initialize'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/actionpack-3.2.2/lib/action_dispatch/middleware/stack.rb:43:in `new'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/actionpack-3.2.2/lib/action_dispatch/middleware/stack.rb:43:in `build'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/actionpack-3.2.2/lib/action_dispatch/middleware/stack.rb:113:in `block in build'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/actionpack-3.2.2/lib/action_dispatch/middleware/stack.rb:113:in `each'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/actionpack-3.2.2/lib/action_dispatch/middleware/stack.rb:113:in `inject'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/actionpack-3.2.2/lib/action_dispatch/middleware/stack.rb:113:in `build'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/engine.rb:470:in `app'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/application/finisher.rb:31:in `block in <module:Finisher>'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/initializable.rb:30:in `instance_exec'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/initializable.rb:30:in `run'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/initializable.rb:55:in `block in run_initializers'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/initializable.rb:54:in `each'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/initializable.rb:54:in `run_initializers'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/application.rb:136:in `initialize!'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/railtie/configurable.rb:30:in `method_missing'
from /Users/tarunsachdeva/Development/rails/workbench/config/environment.rb:5:in `<top (required)>'
from /Users/tarunsachdeva/Development/rails/workbench/config.ru:4:in `require'
from /Users/tarunsachdeva/Development/rails/workbench/config.ru:4:in `block in <main>'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/builder.rb:51:in `instance_eval'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/builder.rb:51:in `initialize'
from /Users/tarunsachdeva/Development/rails/workbench/config.ru:1:in `new'
from /Users/tarunsachdeva/Development/rails/workbench/config.ru:1:in `<main>'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/builder.rb:40:in `eval'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/builder.rb:40:in `parse_file'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/server.rb:200:in `app'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/commands/server.rb:46:in `app'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/server.rb:301:in `wrapped_app'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/rack-1.4.1/lib/rack/server.rb:252:in `start'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/commands/server.rb:70:in `start'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/commands.rb:55:in `block in <top (required)>'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/commands.rb:50:in `tap'
from /Users/tarunsachdeva/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.2.2/lib/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
任何和所有的帮助表示赞赏。