Adding paypal subscriptions to your rails application

Nov 2010

I looked at some of the solutions for adding Paypal subscriptions to my site and there are a few. My main issue was that some seem to add models and controllers, others are plugins, and still others actually just don't work. I wanted a 1 controller solution. So here's a very simple controller that handles the Paypal IPN for subscriptions. To use this controller you'll need to create a subscription button. I did this via the Paypal admin by going to "Profile" and selecting "My Saved Button". This will then create you some button code that looks like he following.

https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YFAC78P5YVMVW&custom=#{custom}&notify_url=#{notify_url}

You'll note I've added my own custom attribute called "custom" which I use to store the plan the customer has selected. I had to create 3 buttons 1 for each plan. You don't need the notify_url as you can set this in your Paypal admin. I've heard anecdotal evidence that Paypal is not the way to go for SaaS sites, but for me during I found it be a reasonable way to sign up. It would be interstiong to see a usability study comparing paypal to other subscription methods. You'll also need to switch on IPN in your Paypal admin to get this to work. Again this is under profile / admin. The controller code is then simply.

class PaypalController < ApplicationController

  protect_from_forgery :except => :paypal_ipn

  # This will be called when soemone first subscribes
  def sign_up_user(custom, plan_id)
    logger.info("sign_up_user (#{custom})")
  end

  # This will be called if someone cancels a payment
  def cancel_subscription(custom, plan_id)
    logger.info("cacnel_subscription (#{custom})")

    a = Account.find(custom.to_i)
    a.active = false
    a.save
  end

  # This will be called if a subscription expires
  def subscription_expired(custom, plan_id)
    logger.info("subscription_expired (#{custom})")

    a = Account.find(custom.to_i)
    a.active = false
    a.save
  end

  # Called if a subscription fails
  def subscription_failed(custom, plan_id)
    logger.info("subscription_failed (#{custom})")

    a = Account.find(custom.to_i)
    a.active = false
    a.save
  end

  # Called each time paypal collects a payment
  def subscription_payment(custom, plan_id)
    logger.info("recurrent_payment_received (#{custom})")

    a = Account.find(custom.to_i)
    a.plan_id = plan_id.to_i
    a.active = true
    a.save
  end

  # process the PayPal IPN POST
  def paypal_ipn

    # use the POSTed information to create a call back URL to PayPal
    query = 'cmd=_notify-validate'
    request.params.each_pair {|key, value| query = query + '&' + key + '=' + 
      value if key != 'register/pay_pal_ipn.html/pay_pal_ipn' }

    paypal_url = 'www.paypal.com'
    if ENV['RAILS_ENV'] == 'development'
      paypal_url = 'www.sandbox.paypal.com'
    end

    # Verify all this with paypal
    http = Net::HTTP.start(paypal_url, 80)
    response = http.post('/cgi-bin/webscr', query)
    http.finish
    
    item_name = params[:item_name]
    item_number = params[:item_number]
    payment_status = params[:payment_status]
    txn_type = params[:txn_type]
    custom = params[:custom]

    # Paypal confirms so lets process.
    if response && response.body.chomp == 'VERIFIED' 

      if txn_type == 'subscr_signup'
        sign_up_user(custom, item_number)
      elsif txn_type == 'subscr_cancel'
        cancel_subscription(custom, item_number)
      elsif txn_type == 'subscr_eot'
        subscription_expired(custom, item_number)
      elsif txn_type == 'subscr_failed'
        subscription_failed(custom, item_number)
      elsif txn_type == 'subscr_payment' && payment_status == 'Completed'
        subscription_payment(custom, item_number)
      end

      render :text => 'OK'

    else
      render :text => 'ERROR'
    end
  end
end