我正在尝试按照一些在线教程在 Rails 中注释我的模型。但是，似乎所有教程都在谈论过时的注释版本或不正确的安装，这是一团糟。
到目前为止，我尝试了以下
1) 在 Gemfile 中添加了这个
gem 'annotate', '2.4.0'
2）然后命令：
bundle install
3）然后我看到注释gem已安装并显示在命令中
bundle show
4）最后为了注释我的模型，我使用了命令
bundle exec annotate --position before
在这一点上，我期待我的模型被注释但是我得到的是以下错误消息：
/Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.1/lib/active_record/railties/databases.rake:4:in `<top (required)>': undefined method `namespace' for main:Object (NoMethodError)
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.1/lib/active_record/railtie.rb:33:in `load'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.1/lib/active_record/railtie.rb:33:in `block in <class:Railtie>'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie.rb:184:in `instance_exec'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie.rb:184:in `block in load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie.rb:184:in `each'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie.rb:184:in `load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/engine.rb:423:in `block in load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/application/railties.rb:8:in `each'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/application/railties.rb:8:in `all'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/engine.rb:423:in `load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/application.rb:145:in `load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.1/lib/rails/railtie/configurable.rb:30:in `method_missing'
from Rakefile:7:in `<top (required)>'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/annotate-2.4.0/lib/annotate.rb:17:in `load'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/annotate-2.4.0/lib/annotate.rb:17:in `load_tasks'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/gems/annotate-2.4.0/bin/annotate:66:in `<top (required)>'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/bin/annotate:19:in `load'
from /Users/AM/.rvm/gems/ruby-1.9.2-p290/bin/annotate:19:in `<main>'
所以感觉完全被难住了。
关于如何进行的任何想法？
谢谢