Rack::Affiliates

Rack::Affiliates is a rack middleware that extracts information about the referrals came from an affiliated site. Specifically, it looks up for specific parameter (ref by default) in the request. If found, it persists affiliate tag, referring url and time in a cookie for later use.

Common Scenario

Affiliate links tracking is very common task if you want to promote your online business. This middleware helps you to do that.

1. You associate an affiliate tag (for eg. ABC123) with your partner.
2. The affiliate promotes your business at http://partner.org by linking to your site with like http://yoursite.org?ref=ABC123.
3. A user clicks through the link and lands on your site.
4. Rack::Affiliates middleware finds ref parameter in the request, extracts affiliate tag and saves it in a cookie
5. User signs up (now or later) and you mark it as a referral from your partner
6. PROFIT!

Installation

Piece a cake:

gem install rack-affiliates

Rails 3 Example Usage

Add the middleware to your application stack:

# Rails 3 App - in config/application.rb
class Application < Rails::Application
  ...
  config.middleware.use Rack::Affiliates
  ...
end

# Rails 2 App - in config/environment.rb
Rails::Initializer.run do |config|
  ...
  config.middleware.use "Rack::Affiliates"
  ...
end

Now you can check any request to see who came to your site via an affiliated link and use this information in your application. Affiliate tag is saved in the cookie and will come into play if user returns to your site later.

class ExampleController < ApplicationController
  def index
    str = if request.env['affiliate.tag] && affiliate = User.find_by_affiliate_tag(request.env['affiliate.tag'])
      "Halo, referral! You've been referred here by #{affiliate.name} from #{request.env['affiliate.from']} @ #{Time.at(env['affiliate.time'])}"
    else
      "We're glad you found us on your own!"
    end
    
    render :text => str
  end
end

Customization

You can customize parameter name by providing :param option (default is ref). By default cookie is set for 30 days, you can extend time to live with :ttl option (default is 30 days).

#Rails 3 in config/application.rb
class Application < Rails::Application
  ...
  config.middleware.use Rack::Affiliates.new, {:param => 'aff_id', :ttl => 3.months}
  ...
end

The :domain option allows to customize cookie domain.

#Rails 3 in config/application.rb
class Application < Rails::Application
  ...
  config.middleware.use Rack::Affiliates.new, :domain => '.example.org'
  ...
end

Middleware will set cookie on .example.org so it's accessible on www.example.org, app.example.org etc.

Credits

Thanks goes to Rack::Referrals (https://github.com/deviantech/rack-referrals) for the inspiration.