Ruby / Rails太令人困惑了。我正在阅读Michael Hartl教程，并且使用以下终端命令收到错误：
$ rails generate scaffold Micropost content:string user_id:integer
给了我：
/Users/johncurry/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency.rb:298:in `to_specs': Could not find 'railties' (>= 0) among 8 total gem(s) (Gem::LoadError)
from /Users/johncurry/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency.rb:309:in `to_spec'
from /Users/johncurry/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_gem.rb:47:in `gem'
from /Users/johncurry/.rvm/rubies/ruby-2.0.0-p247/bin/rails:22:in `<main>'
我真的不知道它在问什么，或者为什么它不起作用。我之前能够生成一个脚手架，而且我在终端的demo_app文件夹中，所以我不知道最新情况，甚至是什么信息都放在这里。 http://ruby.railstutorial.org/chapters/a-demo-app#fig-demo_micropost_model是链接，我坚持第2.3.1节
$bundle show
/Users/johncurry/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency.rb:298:in `to_specs': Could not find 'bundler' (>= 0) among 8 total gem(s) (Gem::LoadError)
from /Users/johncurry/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/dependency.rb:309:in `to_spec'
from /Users/johncurry/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/core_ext/kernel_gem.rb:47:in `gem'
from /Users/johncurry/.rvm/rubies/ruby-2.0.0-p247/bin/bundle:22:in `<main>'