执行“rails s"时出现名称错误 [英] NameError on executing 'rails s'
本文介绍了执行“rails s"时出现名称错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我为 Rails 开始了本教程.我刚刚创建了应用程序并准备测试默认的欢迎页面，结果发生了:
I started this tutorial for Rails. I just created the app and was going to test the default welcome page and this happened:
D:\Programming\Rails Projects\simpleCMS>rails server
C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/actionview-4.2.3/lib/action_view/helpers.rb:40:in `<module:Helpers>': uninitialized constant ActionView::Helpers::ActiveModelHelper (NameError)
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/actionview-4.2.3/lib/action_view/helpers.rb:4:in `<module:ActionView>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/actionview-4.2.3/lib/action_view/helpers.rb:3:in `<top (required)>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/actionview-4.2.3/lib/action_view/base.rb:5:in `require'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/actionview-4.2.3/lib/action_view/base.rb:5:in `<top (required)>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/web-console-2.2.1/lib/web_console/template.rb:7:in `<class:Template>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/web-console-2.2.1/lib/web_console/template.rb:6:in `<module:WebConsole>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/web-console-2.2.1/lib/web_console/template.rb:1:in `<top (required)>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/web-console-2.2.1/lib/web_console.rb:12:in `require'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/web-console-2.2.1/lib/web_console.rb:12:in `<top (required)>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/web-console-2.2.1/lib/web-console.rb:1:in `require'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/web-console-2.2.1/lib/web-console.rb:1:in `<top (required)>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in `require'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in `block (2 levels) in require'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in `each'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in `block in require'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in `each'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in `require'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/bundler-1.10.6/lib/bundler.rb:134:in `require'
from D:/Programming/Rails Projects/simpleCMS/config/application.rb:7:in `<top (required)>'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:78:in `require'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:78:in `block in server'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:75:in `tap'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:75:in `server'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/railties-4.2.3/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
from C:/Ruby22-x64/lib/ruby/gems/2.2.0/gems/railties-4.2.3/lib/rails/commands.rb:17:in `<top (required)>'
from bin/rails:4:in `require'
from bin/rails:4:in `<main>'
我的 gemfile(没有注释):
My gemfile (without the comments):
source 'https://rubygems.org'
gem 'rails', '4.2.3'
gem 'mysql2'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0', group: :doc
group :development, :test do
gem 'byebug'
gem 'web-console', '~> 2.0'
end
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
推荐答案
卸载 railties gem，因为仅卸载 rails gem 不起作用.然后安装一个旧版本的 rails gem(在我的例子中是 4.0.0，因为那是教程中的那个).
Uninstall railties gem because just uninstalling the rails gem doesn't work. Then install an older version of the rails gem (4.0.0 in my case because that was the one from the tutotial).
这解决了问题.
这篇关于执行“rails s"时出现名称错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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