Implementing a Referral System in Rails

We recently implemented a referral system for Cravd, our marketplace platform that connects customers with personal home chefs. As we've been growing organically through word of mouth, we wanted to accelerate this growth by implementing a formal referral program. Here's how we set it up using the Refer gem in our Rails application.

Setting Up the Refer Gem

First, we added the Refer gem to our Gemfile:

gem "refer"

After running bundle install, we generated the necessary migrations:

rails generate refer:install
rails db:migrate

This set up the basic database structure for tracking referrals.

Configuring the Referral Code Generator

We customized the referral code generation in an initializer file:

# config/initializers/refer.rb

Refer.code_generator = lambda do |referrer|
  get_existing_code(referrer).presence || generate_new_code(referrer.id)
end

Refer.param_name = :code

private

def get_existing_code(referrer)
  referrer.referral_codes.last&.code
end

def generate_new_code(referrer_id)
  letters = ("A".."Z").to_a.sample(4).join
  padded_id = referrer_id.to_s.rjust(4, "0")
  "#{letters}-#{padded_id}"
end

This creates unique, readable codes combining random letters and the referrer's ID.

Integrating with User Model

We added the has_referrals macro to our User model:

class User < ApplicationRecord
  has_referrals
  # ... other code ...
end

Handling Referrals in the Controller

We updated our RegistrationsController to handle referrals during sign up:

class RegistrationsController < ApplicationController
  def create
    @user = User.new(user_params)
    if @user.save
      refer @user
      start_new_session_for @user
      send_welcome_email
      redirect_to after_authentication_url, notice: "Welcome to Cravd!"
    else
      render :new, status: :unprocessable_content
    end
  end
end

Handling Referrals in the Controller

In our ReferralsController, we implemented two key methods to manage referral codes and cookies:

class ReferralsController < ApplicationController
  set_referral_cookie only: [:show], if: -> { Current.user.blank? && !browser.bot? }
  before_action :set_referral_code, only: [:index, :show]

  private

  def set_referral_code
    return unless Current.user
    @referral_code = Current.user.referral_codes.last || Current.user.referral_codes.create
  end
end

The set_referral_cookie method is used to store the referral code in a cookie when it's present in the request parameters, and set_referral_code method is used to create or retrieve a referral code for the current user. It’s used in the referrals controllers where I want to display the user's referral code.

Conclusion

With these pieces in place, we now have a functional referral system. Users can generate unique referral codes, share them, and we can track successful referrals. This implementation provides a solid foundation for our referral program, which we'll build upon to create a comprehensive reward system.