1-inline-bus.rb

class DonationsController # < ActionController::Base
  def create
    donation_service.add_donation(current_user, params, bus.on(
      donation_created: ->(donation) { send_user_to_payment_gateway(donation) },
      donation_invalid: ->(donation) { render donation.errors, status: :bad_request }
    ))
  end

  private
  def donation_service
    DonationService.new # inject dependencies
  end 
  
  def send_user_to_payment_gateway(donation)
    #...
  end
end

2-self-listener.rb

class DonationsController # < ActionController::Base
  def create
    build_service.create_donation(current_user, params, bus.attach(self))
  end
  
  def donation_created(donation)
    send_user_to_payment_gateway(donation)
  end
  
  def donation_invalid(donation)
    donation_invalid: ->(donation) { render donation.errors, status: :bad_request }
  end

  private
  def send_user_to_payment_gateway(donation)
    #...
  end
  
  protected
  def build_service
    DonationService.new # inject dependencies
  end 
end

3-rails-on-bus.rb

class DonationsController # < ActionController::Base
  include Bus::ServiceController.new(service: DonationService, event_prefix: :donation, actions: :create)
  
  def donation_created(donation)
    send_user_to_payment_gateway(donation)
  end
  
  def donation_invalid(donation)
    render donation.errors, status: :bad_request
  end

  private
  def send_user_to_payment_gateway(donation)
    #...
  end
  
  protected
  def service_parameters
    [current_user, params]
  end
end

4-rails-on-bus-implicit.rb

class DonationsController # < ActionController::Base
  include Bus::ServiceController.new(actions: :create) # implicit from controller name
  
  def donation_created(donation)
    send_user_to_payment_gateway(donation)
  end
  
  def donation_invalid(donation)
    render donation.errors, status: :bad_request
  end

  private
  def send_user_to_payment_gateway(donation)
    #...
  end
  
  protected
  def service_parameters
    [current_user, params]
  end
end

5-dsl.rb

class DonationsController # < ActionController::Base
  service_actions :create

  def donation_created(donation)
    send_user_to_payment_gateway(donation)
  end
  
  def donation_invalid(donation)
    render donation.errors, status: :bad_request
  end

  private
  def send_user_to_payment_gateway(donation)
    #...
  end
  
  protected
  def service_parameters
    [current_user, params]
  end
end