在Ruby on Rails中使用Markdown的方法

实现 Markdown 语法和代码语法高亮分别是用的 Redcarpet 和 pygments.rb 两个 Gem：

https://github.com/vmg/redcarpet

https://github.com/tmm1/pygments.rb

https://github.com/richleland/pygments-css

http://pygments.org/docs/lexers/

在/Gemfile中添加如下两行：

gem 'redcarpet'

gem 'pygments.rb'

需要说明的是，pygments.rb 依赖于 Python，所以确保机器已经安装了 Python 2.x。

然后在/app/controllers/comments_controller.rb中添加相应 redcarpet 和 pygments.rb 的代码：

class ApplicationController < ActionController::Base

# Prevent CSRF attacks by raising an exception.

# For APIs, you may want to use :null_session instead.

protect_from_forgery with: :exception

helper_method [:markdown]

# Highlight code with Pygments

class HTMLwithPygments < Redcarpet::Render::HTML

def block_code(code, language)

language = "text" if language.blank?

sha = Digest::SHA1.hexdigest(code)

Rails.cache.fetch ["code", language, sha].join("-") do

Pygments.highlight(code, :lexer => language)

end

end

end

protected

# Markdown with Redcarpet

def markdown(text)

renderer = HTMLwithPygments.new({

:filter_html => true,

:hard_wrap => true,

:link_attributes => {:rel => 'external nofollow'}

})

options = {

:autolink => true,

:no_intra_emphasis => true,

:fenced_code_blocks => true,

:lax_html_blocks => true,

:strikethrough => true,

:superscript => true,

:tables => true

}

Redcarpet::Markdown.new(renderer, options).render(text).html_safe

end

end

最后在 View 中就可以直接调用 markdown 方法来处理博客正文了：

<%= markdown @post.content %>

语法规则类似 Github 上的 Markdown，码字效率大大提高。