gistfile1.rb

  def paypal_ipn
    notify = Paypal::Notification.new(request.raw_post)
 
    donations = Donation.find_all_from_paypal(notify.params)
    user = donations.first.user
    purchase = Purchase.new(:donations => donations, :user => user)
    purchase.paypal_transaction_id = notify.transaction_id
 
    if notify.acknowledge
      if notify.complete? and purchase.total_amount == BigDecimal.new(notify.amount.to_s)
        purchase.save
      else
        logger.error("PayPal acknowledgement was unpaid or the amounts didn't match for the following transaction: #{notify.params['txn_id']}")
      end
    else
      logger.error("Failed to verify Paypal's notification, please investigate: #{notify.params['txn_id']}")
    end
 
    render :nothing => true
  end