1. Устанавливаем новую версию Ruby. После ее установки в командной строке набираем обычную команду для установки Rails и….

C:\>gem install rails

ERROR: Error installing rails:

The 'json' native gem requires installed build tools.

Please update your PATH to include build tools or download the DevKit

from 'http://rubyinstaller.org/downloads' and follow the instructions

at 'http://github.com/oneclick/rubyinstaller/wiki/Development-Kit'

Вот такой код ошибки. Не установлен один из джемов - “json”.

1. Чтобы исправить это, для начала нам необходимо скачать и поместить на диск пакет Development Kit отсюда http://rubyinstaller.org/downloads/ ,который в помогает активировать многие расширения C/C++ для Ruby. Затем мы переходим в командной строке в папку, где находится этот пакет и выполняем команды его инициализации и установки:

C:\>cd c:\rbytools

C:\rbytools>ruby dk.rb init

[INFO] found RubyInstaller v1.9.2 at C:/Ruby192

Initialization complete! Please review and modify the auto-generated

'config.yml' file to ensure it contains the root directories to all

of the installed Rubies you want enhanced by the DevKit.

C:\rbytools>ruby dk.rb install

[INFO] Installing 'C:/Ruby186/lib/ruby/site_ruby/1.8/rubygems/defaults/operating

_system.rb'

[INFO] Installing 'C:/Ruby186/lib/ruby/site_ruby/devkit.rb'

[INFO] Updating convenience notice gem override for 'C:/Ruby192'

[INFO] Installing 'C:/Ruby192/lib/ruby/site_ruby/devkit.rb'

2. И на конец, запускаем:

C:\rbytools>gem update --system

Updating rubygems-update

Fetching: rubygems-update-1.8.11.gem (100%)

Successfully installed rubygems-update-1.8.11

Installing RubyGems 1.8.11

RubyGems 1.8.11 installed

== 1.8.11 / 2011-10-03

* Bug fix:

* Deprecate was moved to Gem::Deprecate to stop polluting the top-level

namespace.

------------------------------------------------------------------------------

RubyGems installed the following executables:

C:/Ruby192/bin/gem

RubyGems system software updated

C:\rbytools>gem install rails -v 3.1.1

Temporarily enhancing PATH to include DevKit...

Building native extensions. This could take a while...

Fetching: rdoc-3.11.gem (100%)

Depending on your version of ruby, you may need to install ruby rdoc/ri data:

<= 1.8.6 : unsupported

= 1.8.7 : gem install rdoc-data; rdoc-data --install

= 1.9.1 : gem install rdoc-data; rdoc-data --install

>= 1.9.2 : nothing to do! Yay!

Fetching: railties-3.1.1.gem (100%)

Fetching: bundler-1.0.21.gem (100%)

Fetching: rails-3.1.1.gem (100%)

Successfully installed json-1.6.1

Successfully installed rdoc-3.11

Successfully installed railties-3.1.1

Successfully installed bundler-1.0.21

Successfully installed rails-3.1.1

5 gems installed

Installing ri documentation for json-1.6.1...

Installing ri documentation for rdoc-3.11...

Installing ri documentation for railties-3.1.1...

Installing ri documentation for bundler-1.0.21...

Installing ri documentation for rails-3.1.1...

Installing RDoc documentation for json-1.6.1...

Installing RDoc documentation for rdoc-3.11...

Installing RDoc documentation for railties-3.1.1...

Installing RDoc documentation for bundler-1.0.21...

Installing RDoc documentation for rails-3.1.1...

Проверяем версии Ruby и Rails

C:\ ruby -v

ruby 1.9.2p290 (2011-07-09) [i386-mingw32]

C:\ rails -v

Rails 3.1.1

Как видите, все просто, хоть и требует некоторого времени и внимания.