NameError：未初始化的常量MongoClient

Question

我正在使用Ruby 2.2。我已经安装了mongo宝石，但仍然得到错误：

MY-MAC:ruby-2.2.0 me$ gem list 

*** LOCAL GEMS *** 

bigdecimal (1.2.6) 
bson (4.0.3) 
bundler (1.10.6) 
bundler-unload (1.0.2) 
executable-hooks (1.3.2) 
gem-wrappers (1.2.7) 
io-console (0.4.3) 
json (1.8.1) 
log4r (1.1.10) 
mini_portile2 (2.0.0) 
minitest (5.4.3) 
mongo (2.2.3) 
nokogiri (1.6.7.2) 
power_assert (0.2.2) 
psych (2.0.8) 
rake (10.4.2) 
rdoc (4.2.0) 
rubygems-bundler (1.4.4) 
rvm (1.11.3.9) 
test-unit (3.0.8) 
MY-MAC:ruby-2.2.0 me$ irb 
2.2.0 :001 > require 'mongo' 
=> true 
2.2.0 :002 > include Mongo 
=> Object 
2.2.0 :003 > Mongo::VERSION 
=> "2.2.3" 
2.2.0 :004 > c = MongoClient.new 
NameError: uninitialized constant MongoClient 
    from (irb):4 
    from /Users/me/.rvm/rubies/ruby-2.2.0/bin/irb:11:in `<main>' 
2.2.0 :005 > 

什么问题？

Answer 1

要实例化对象是Mongo::Client.new

Docs are here.