Markdown and code syntax highlighting in Ruby on Rails (using RedCarpet and CodeRay)

Markdown is a popular text-to-HTML conversion tool. In order to use Markdown with code syntax highlighting, use RedCarpet and CodeRay gems. Ryan Bates made a Railscast episode (#272) on RedCarpet, but it is somewhat outdated now. The episode has more dependencies and uses a deprecated Albino gem.

Place the following in the Rails app.

Gemfile

gem 'redcarpet', '~> 2.1.1'
gem 'coderay', '~> 1.0.7'

application_helper.rb

class CodeRayify < Redcarpet::Render::HTML
  def block_code(code, language)
    CodeRay.scan(code, language).div
  end
end

def markdown(text)
  coderayified = CodeRayify.new(:filter_html => true, 
                                :hard_wrap => true)
  options = {
    :fenced_code_blocks => true,
    :no_intra_emphasis => true,
    :autolink => true,
    :strikethrough => true,
    :lax_html_blocks => true,
    :superscript => true
  }
  markdown_to_html = Redcarpet::Markdown.new(coderayified, options)
  markdown_to_html.render(text).html_safe
end

whatever_view_file.html.erb

<%= markdown(@submission.content) %>

The result is this gorgeous looking syntax highlighting.

To indicate language you are using the code should be wrapped around the following.

``` ruby
some_code_here
```

Also make sure that you do bundle install and restart your server.

Alternatively, if you’d like to line number on your code, you can change this line …

CodeRay.scan(code, language).div

to the following.

CodeRay.scan(code, language).div(:line_numbers => :table)

This was posted 10 months ago. It has 3 notes.

jfong23 likes this
stevekinney likes this
mehulkar likes this
allfuzzy posted this

All Fuzzy

Markdown and code syntax highlighting in Ruby on Rails (using RedCarpet and CodeRay)