Class: Rack::Prerender

Inherits:
Object
  • Object
show all
Defined in:
lib/prerender_rails.rb

Instance Method Summary collapse

Constructor Details

#initialize(app, options = {}) ⇒ Prerender

Returns a new instance of Prerender.



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# File 'lib/prerender_rails.rb', line 5

def initialize(app, options={})
  # googlebot, yahoo, and bingbot are not in this list because
  # we support _escaped_fragment_ instead of checking user
  # agent for those crawlers
  @crawler_user_agents = [
    # 'googlebot',
    # 'yahoo',
    # 'bingbot',
    'baiduspider',
    'facebookexternalhit'
  ]

  @extensions_to_ignore = [
    '.js',
    '.css',
    '.less',
    '.png',
    '.jpg',
    '.jpeg',
    '.gif',
    '.pdf',
    '.doc',
    '.txt',
    '.zip',
    '.mp3',
    '.rar',
    '.exe',
    '.wmv',
    '.doc',
    '.avi',
    '.ppt',
    '.mpg',
    '.mpeg',
    '.tif',
    '.wav',
    '.mov',
    '.psd',
    '.ai',
    '.xls',
    '.mp4',
    '.m4a',
    '.swf',
    '.dat',
    '.dmg',
    '.iso',
    '.flv',
    '.m4v',
    '.torrent'
  ]

  @options = options
  @options[:whitelist] = [@options[:whitelist]] if @options[:whitelist].is_a? String
  @options[:blacklist] = [@options[:blacklist]] if @options[:blacklist].is_a? String
  @app = app
end

Instance Method Details

#build_api_url(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 117

def build_api_url(env)
  url = Rack::Request.new(env).url
  prerender_url = get_prerender_service_url()
  forward_slash = prerender_url[-1, 1] == '/' ? '' : '/'
  "#{prerender_url}#{forward_slash}#{url}"
end

#call(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 61

def call(env)

  if should_show_prerendered_page(env)
    prerendered_response = get_prerendered_page_response(env)

    if prerendered_response && prerendered_response.is_a?(Net::HTTPSuccess)
      response = Rack::Response.new(prerendered_response.body, 200, [])
      return response.finish
    end
  end

  @app.call(env)  
end

#get_prerender_service_url ⇒ Object 



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# File 'lib/prerender_rails.rb', line 124

def get_prerender_service_url
  ENV['PRERENDER_SERVICE_URL'] || 'http://prerender.herokuapp.com/'
end

#get_prerendered_page_response(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 109

def get_prerendered_page_response(env)
  begin
    Net::HTTP.get_response(URI.parse(build_api_url(env)))
  rescue
    nil
  end
end

#should_show_prerendered_page(env) ⇒ Object 



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# File 'lib/prerender_rails.rb', line 75

def should_show_prerendered_page(env)
  user_agent = env['HTTP_USER_AGENT']
  return false if !user_agent

  request = Rack::Request.new(env)

  return true if request.query_string.include? '_escaped_fragment_'
  
  #if it is not a bot...dont prerender
  return false if @crawler_user_agents.all? { |crawler_user_agent| !user_agent.downcase.include?(crawler_user_agent.downcase) }

  #if it is a bot and is requesting a resource...dont prerender
  return false if @extensions_to_ignore.any? { |extension| request.path.include? extension }

  #if it is a bot and not requesting a resource and is not whitelisted...dont prerender
  return false if @options[:whitelist].is_a?(Array) && @options[:whitelist].all? { |whitelisted| !Regexp.new(whitelisted).match(request.path) }

  #if it is a bot and not requesting a resource and is not blacklisted(url or referer)...dont prerender
  if @options[:blacklist].is_a?(Array) && @options[:blacklist].any? { |blacklisted|
      blacklistedUrl = false
      blacklistedReferer = false
      regex = Regexp.new(blacklisted)

      blacklistedUrl = !!regex.match(request.path)
      blacklistedReferer = !!regex.match(request.referer) if request.referer

      blacklistedUrl || blacklistedReferer
    }
    return false
  end 

  return true
end