1_before_controller.rb

# This is a pretty standard controller action in our codebase. Maybe it might
# get rolled up into a service object but it's unlikely. This code is smelly 
# because it's making decisions based on the return value of an object it
# doesn't own.
class DonationsController < ApplicationController
  def create
    mailer.notify_supporter donation
    if charity.active?
      mailer.receipt donation
      mailer.notify_charity donation
    else
      mailer.payment_advice donation
      mailer.initiate_kyc charity
    end
    
    redirect_to somewhere_url
  end
end

2_1_after_controller.rb

# Delegate the responsibility of which emails to send to charity. In this
# situation Charity essentially acts as a service object.
class DonationsController < ApplicationController
  def create
    charity.send_post_donation_notifications donation
    
    redirect_to somewhere_url
  end
end

2_2_after_charity.rb

# Now it's charities decision what emails to send depending on its state. What
# is awesome about this code is that charity can define more states with
# different emails (or any type of notification) and the controller + tests do
# not change!
class Charity < ActiveRecord::Base
  def send_post_donation_notifications donation, mail = PostDonationMailer.delay
    mail.notify_supporter donation
    if charity.active?
      mail.receipt donation
      mail.notify_charity donation
    else
      mail.payment_advice donation
      mail.initiate_kyc self
    end
end