Rails++ - Talk given at Lyon.rb meetup in October 2012

000_intro.md

Enterprise Rails

   WAT?

Lyon.rb - Octobre 2012

Philippe Creux - @pcreux - http://pcreux.com

010_typical_rails_app.md

Typical Rails App

• Models
• Controllers
• Views
• Helpers
• Rake tasks

020_after_a_while.md

Typical Rails App (J+30)

• Fat Models
• Fat Controllers
• Complex Views
• ZOMG Helpers
• WTF Rake tasks

030_advices.md

Advice from the 2000's

Just do...

• Thin Controllers
• Fat Models

040_thin_c_fat_m.rb

class UserController < ApplicationController
  def create
    user = User.create!(params[:user])
    redirect_to home_path, notice: "Welcome!"
  end
end

050_fat_m.rb

class User < ActiveRecord::Base
  after_create :create_account
  after_create :send_welcome_email
  after_create :update_user_count
  after_create :ring_the_bell

  def create_account
    # ...
  end

  def send_welcome_email
    # ActionMailer...
  end
end

060_fat_m_meh.md

WRONG!

• Callbacks spaghetti
• Slow tests (Store a user => send welcome email?!)
• Single Responsibility Principle (troll)

065_wrap.md

Let's wrap the Business Logic into a method...

and put this method into... the model!

070_fat_m_like_a_service.rb

class UserController < ApplicationController
  def create
    user = User.signup(params)
    redirect_to home_path, notice: "Welcome!"
  end
end

class User < ActiveRecord::Base
  def self.signup(params)
    user = User.create!(params[:user])
    user.accounts.create!
    Mailer.send_welcome_email(user)

    user
  end
end

080_service_to_the_rescue.md

Service to the Rescue!

Move Business Logic to UserSignupService.

app/services/user_signup_service.rb

090_service.rb

class UserController < ApplicationController
  def create
    user = UserSignupService.signup(params[:user])
    redirect_to home_path, notice: "Welcome!"
  end
end

# app/services/user_signup_service.rb
class UserSignupService
  def self.signup(user_params)
    user = User.create!(user_params)
    user.accounts.create!
    Mailer.send_welcome_email(user)

    user
  end
end

100_service_pp.rb

class UserSignupService < Struct.new(:params, :user)
end

class UserSignupService
  attr_reader :params, :user

  def initialize(params, user)
    @params = params
    @user = params
  end
end

105_decorators.md

Decorators!

110_decorators.rb

class User < ActiveRecord::Base
  def full_name
    [first_name, last_name].compact.join(' ')
  end

  def age
    (Time.now - birthday) / (3600 * 24 * 365)
  end

  def age_in_words
    age > 1 ? "#{age} years old" : "baby"
  end
end

120_decorators.rb

module UserHelpers
  def full_name(user)
    [user.first_name, user.last_name].compact.join(' ')
  end

  def age(user)
    (Time.now - user.birthday) / (3600 * 24 * 365)
  end

  def age_in_words(age)
    age > 1 ? "#{age} years old" : "baby"
  end
end

130_decorators.rb

class ICTM::UserDecorator < Draper::Base
  decorates :user, class: User

  def full_name
    [user.first_name, user.last_name].compact.join(' ')
  end

  def age
    (Time.now - user.birthday) / (3600 * 24 * 365)
  end

  def age_in_words
    user.age > 1 ? "#{user.age} years old" : "baby"
  end
end

user = User.first.decorate
user.full_name

140_presenters.md

When you need to aggregate / process data...

Examples:

• Build an Activity Stream
• Aggregate values for a charting library
• ...

... use Presenters!

150_presenters.rb

# app/presenters/user_activity_presenter.rb
class UserActivityPresenter
  # @return [Array] of [Events]
  def self.activity_for_user(user)
    # ...
  end
end

160_tasks.rb

describe "Send newsletter to users"
task :send_newsletter do
  User.find_each do |user|
    if user.subscribed_to_mailing_list?
      puts "User ##{user.id} subscribed to mailing list"
      puts "Sending..."
      begin
        Mailer.send_newsletter!(user)
        puts "Newsletter sent successfuly!"
      rescue
        puts "Ooops, something went wrong"
        puts $!.message
      end
    else
      puts "User ##{user.id} not subscribed to mailing list. Skipping..."
    end
  end
end

165_tasks.txt

170_tasks.rb

describe "Send newsletter to users"
task :send_newsletter do
  SendNewsletterTask.send
end

# app/tasks/send_newsletter_task.rb
class SendNewsletterTask
  def self.send
    puts "Sending newsletter"
    User.find_each do |user|
      # ....
    end
    puts "Done sending newsletter"
  end
end

180_jobs.md

Jobs...

Wrap them into a class...

190_responsibilities.md

Responsibilities

Service: Business Logic Decorator: Decorate a model with ~helper methods Presenter: Aggregate data Task: Do and log

200_responsiblities.md

Responsibilities

Service: Business Logic Decorator: Cool data Presenter: Aggregate data Task: Do and log Helpers: Return HTML snippet. (use partials instead?) Controller: Receive request, call service or presenter, redirect or render Model: Persistence, Validations & Scopes

300_example.rb

class PagesController < ApplicationController
  def show
    @articles = Article.where(['
      (location_id = ?
      OR location_id = 0)
      AND category = ?
      ', current_user.member.location_id, params[:id]
    ]).order('created_at DESC')

    @locations = Location.all
  end
end

310_example.rb

class PagesController < ApplicationController
  def show
    @articles = ArticlePresenter.latest_articles(user, params[:id])

    @locations = Location.all
  end
end

325_example.rb

class PagesController < ApplicationController
  def show
    @articles = ArticlePresenter.latest_articles(user, params[:id])

    @locations = Location.all
  end
end

class ArticlePresenter
  def self.latest_articles(user, category)
    Article.where(['
      (location_id = ?
      OR location_id = 0)
      AND category = ?
      ', user.member.location_id, category
    ]).order('created_at DESC') 
  end
end

330_example.rb

class ArticlePresenter
  def self.latest_articles(user, category)
    Article.for_location(user.member.location).
      for_category(category).latest
  end
end

335_example.rb

class ArticlePresenter
  def self.latest_articles(user, category)
    Article.for_location(user.member.location).for_category(category).latest
  end
end

class Article < ActiveRecord::Base
  scope :for_location, lambda { |location| where(location_id: [location.id, 0]) }
  scope :for_category, lambda { |category| where(category: category) }
  scope :latest, order('created_at DESC')
end

400_conclusion.md

Responsibilities

Service: Business Logic Decorator: Cool data Presenter: Aggregate data Task: Do and log Helpers: Return HTML snippet. (use partials instead?) Controller: Receive request, call service or presenter, redirect or render Model: Persistence, Validations & Scopes