実行後にmongo3を実行するとgem install mongo3。私は以下の問題を抱えています
F, [2013-05-08T20:35:18.376873 #8487] FATAL -- : undefined method `helpers' for CollectionHelper:Module (NoMethodError)
/Users/shuxuan/.rvm/gems/ruby-1.9.3-p392@rails3tutorial2ndEd/gems/mongo3-0.1.5/lib/helpers/collection_helper.rb:15:in `<module:CollectionHelper>'
/Users/shuxuan/.rvm/gems/ruby-1.9.3-p392@rails3tutorial2ndEd/gems/mongo3-0.1.5/lib/helpers/collection_helper.rb:14:in `<top (required)>'
/Users/shuxuan/.rvm/gems/ruby-1.9.3-p392@rails3tutorial2ndEd/gems/mongo3-0.1.5/lib/mongo3.rb:49:in `load'