A step-by-step process for simplifying controller code in Ruby on Rails applications, with code examples. First presented at Philly.rb September 2014.

1. Simplify
Your Rails Controllers
With a Vengeance

2. Brian Auton
brianauton@gmail.com
twitter.com/brianauton
github.com/brianauton

3. I know what's wrong
with your Rails app...

4. The controllers
(they're too complex)

5. 1. Less responsibilities
2. Shorter methods
3. Less duplication

6. 1. Less responsibilities
2. Shorter methods
3. Less duplication
Controllers are just code.

7. 1. Less responsibilities
User's Intent <=> Business Logic

8. 1. Less responsibilities
User's Intent <=> Business Logic
How? REST

9. routes.rb
resources :clients do
get :download_pdf, on: :member
end
clients_controller.rb
def download_pdf
client = Client.find params[:id]
send_data client.to_pdf, type: :pdf
end
def show
@client = Client.find params[:id]
end

10. routes.rb
resources :clients
clients_controller.rb
def show
@client = Client.find params[:id]
respond_to do |format|
format.html {}
format.pdf do
send_data @client.to_pdf, type: :pdf
end
end
end

11. routes.rb
resources :orders do
post :submit, on: :member
end
orders_controller.rb
def submit
order = Order.find params[:id]
PaymentGateway.process order
flash[:notice] = “Payment successful”
order.update_attribute :status, :complete
rescue PaymentGateway::Error => e
order.update_attribute :status, :failed
redirect_to order, alert: “Error: #{e}”
end

12. routes.rb
resources :orders
resources :payment_attempts, only: :create
payment_attempts_controller.rb
def create
attempt = PaymentAttempt.create payment_attempt_params
PaymentGateway.process attempt.order
flash[:notice] = “Payment successful”
attempt.update_attribute :status, :complete
rescue PaymentGateway::Error => e
attempt.update_attribute :error, e.message
redirect_to attempt.order, alert: “Error: #{e.message}”
end

13. routes.rb
resources :regions do
put :sort, on: :collection
end
regions_controller.rb
def sort
params[:region].each do |id, position|
Region.find(id).update_attribute :position, position
end
end

14. routes.rb
resources :regions
resources :region_collections, only: :update
region_collections_controller.rb
def update
region_collection_params.each do |attributes|
Region.find(attributes[:id)].update_attributes attributes
end
end
private
def region_collection_params
params.require(:region_collection).permit [:id, :position]
end

15. 2. Shorter methods

16. 2. Shorter methods
How? Delegate to models

17. payment_attempts_controller.rb
def create
attempt = PaymentAttempt.create payment_attempt_params
PaymentGateway.process attempt.order
flash[:notice] = “Payment successful”
attempt.update_attribute :status, :complete
rescue PaymentGateway::Error => e
attempt.update_attribute :error, e.message
redirect_to attempt.order, alert: “Error: #{e.message}”
end

18. payment_attempt.rb
class PaymentAttempt < ActiveRecord::Base
before_save do
PaymentGateway.process order
rescue PaymentGateway::Error => e
update_attribute :error, e.message
end
def successful?
error.present?
end
end

19. payment_attempts_controller.rb
def create
@attempt = PaymentAttempt.create payment_attempt_params
if @attempt.successful?
flash[:notice] = “Payment successful.”
else
flash[:alert] = “Error: #{@attempt.error}”
redirect_to @attempt.order
end
end

20. users_controller.rb
def update
@user = User.find params[:id]
@user.update_attributes user_params
@user.address.update_attributes address_params
...
end
def user_params
params.require(:user).permit :name, :email
end
def address_params
params.require(:address).permit :city, :state, :zip
end

21. users_controller.rb
def update
@user = User.find params[:id]
@user.update_attributes user_params
...
end
def user_params
params.require(:user).permit :name, :email, {
address_attributes: [:city, :state, :zip]
}
end
user.rb
has_one :address
accepts_nested_attributes_for :address

22. 3. Reduce Duplication

23. 3. Reduce Duplication
How? It's just code.

24. widgets_controller.rb
def new
@widget = Widget.new
end
def show
@widget = Widget.find params[:id]
end
def update
@widget = Widget.find params[:id]
...
end

25. widgets_controller.rb
before_action :build_widget, only: [:new]
before_action :find_widget, only: [:show, :update]
private
def build_widget
@widget = Widget.new
end
def find_widget
@widget = Widget.find params[:id]
end

26. application_controller.rb
protected
def build_member
set_member_instance_variable collection.new
end
def find_member
set_member_instance_variable collection.find(params[:id])
end
def set_member_instance_variable(value)
variable_name = “@#{controller_name.singularize}”
instance_variable_set variable_name, (@member = value)
end
def collection
controller_name.classify.constantize
end

27. assets_controller.rb
def update
if @asset.update_attributes asset_params
redirect_to @asset, notice: “Asset updated”
else
flash[:alert] = @asset.errors.full_messages.join(', ')
render :edit
end
end
surveys_controller.rb
def update
if @survey.update_attributes survey_params
redirect_to @survey, notice: “Survey updated”
else
flash[:alert] = @survey.errors.full_messages.join(', ')
render :edit
end
end

28. assets_controller.rb
def update
@asset.update_attributes asset_params
respond_to_update @asset
end
surveys_controller.rb
def update
@survey.update_attributes survey_params
respond_to_update @survey
end
application_controller.rb
def respond_to_update(model)
if model.valid?
type = model.class.name.humanize
redirect_to model, notice: “#{type} updated”
else
flash[:alert] = model.errors.full_messages.join(', ')
render :edit
end
end

29. shared_rest_actions.rb
module SharedRestActions
def self.included(base)
base.before_action :build_member, only: [:new, :create]
base.before_action :find_collection, only: :index
base.before_action :find_member, except: [:index, :new, :create]
end
def index
end
def update
member_params = send “#{controller_name.singularize}_params”
@member.update_attribute member_params
respond_to_update @member
end
...
end

30. assets_controller.rb
class AssetsController < ApplicationController
include SharedRestActions
before_action :paginate, only: :index
before_action :sort_by_date, only: :index
end
surveys_controller.rb
class SurveysController < ApplicationController
include SharedRestActions
before_action :build_member, only: :index
end

31. Recap:
1. Less responsibilities (REST)
2. Shorter methods (Models)
3. Less duplication

32. Go try it out!
brianauton@gmail.com
twitter.com/brianauton
github.com/brianauton