- The document discusses moving away from the traditional "rails way" architecture to a more modular architecture for a Rails application. - It describes splitting the application into separate frontend (AngularJS) and backend (Rails API) components. The Rails backend is refactored using patterns like entities, repositories, and presenters to separate concerns and improve testability/reusability. - Examples demonstrate implementing validation modules, form objects, service classes, and separating domain logic from data access using a repository pattern with the Sequel ORM rather than ActiveRecord. This leads to a cleaner architecture.

1. From rails-way to
modular architecture
Ivan Nemytchenko,
independent consultant
DevConf 2014
@inem, @inemation

2. Icon made by <a href="http://www.freepik.com" alt="Freepik.com">Freepik</a>
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4. 4 bit.ly/rails-community

6. !"---→----→----→----→----#

7. Rails-way

8. Модульная архитектура -
это что?
4 изменения в коде делать легко
4 код легко переиспользовать
4 код легко тестировать

9. Чем плох rails-
way?

10. Single Responsibility
Principle
- Не, не слышали

11. Skinny controllers,
fat models.
ORLY?

12. Conventions over
configuration
DB ⇆ Forms

13. Проект
4 Монолитное приложение на Grails
4 База данных на 70 таблиц
4 Мы упоролись

14. Решение заказчика
4 Фронтенд на AngularJS
4 Бэкэнд на рельсе для отдачи API

15. Ок, rails, значит
rails
Точнее, rails-api

16. Модели
class ImageSettings < ActiveRecord::Base
end
class Profile < ActiveRecord::Base
self.table_name = 'profile'
belongs_to :image, foreign_key: :picture_id
end

17. Модели
class Image < ActiveRecord::Base
self.table_name = 'image'
has_and_belongs_to_many :image_variants,
join_table: "image_image",
class_name: "Image",
association_foreign_key: :image_images_id
belongs_to :settings,
foreign_key: :settings_id,
class_name: 'ImageSettings'
belongs_to :asset
end

18. RABL - github.com/nesquena/
rabl
collection @object
attribute :id, :deleted, :username, :age
node :gender do |object|
object.gender.to_s
end
node :thumbnail_image_url do |obj|
obj.thumbnail_image.asset.url
end
node :standard_image_url do |obj|
obj.standard_image.asset.url
end

19. !-"--→----→----→----→----#

20. def redeem
unless bonuscode = Bonuscode.find_by_hash(params[:code])
render json: {error: 'Bonuscode not found'}, status: 404 and return
end
if bonuscode.used?
render json: {error: 'Bonuscode is already used'}, status: 404 and return
end
unless recipient = User.find_by_id(params[:receptor_id])
render json: {error: 'Recipient not found'}, status: 404 and return
end
unless ['regular', 'paying'].include?(recipient.type)
render json: {error: 'Incorrect user type'}, status: 404 and return
end
ActiveRecord::Base.transaction do
amount = bonuscode.mark_as_used!(params[:receptor_id])
recipient.increase_balance!(amount)
if recipient.save && bonuscode.save
render json: {balance: recipient.balance}, status: 200 and return
else
render json: {error: 'Error during transaction'}, status: 500 and return
end
end
end

22. def redeem
begin
recipient_balance = ??????????
rescue BonuscodeNotFound, BonuscodeIsAlreadyUsed, RecipientNotFound => ex
render json: {error: ex.message}, status: 404 and return
rescue IncorrectRecipientType => ex
render json: {error: ex.message}, status: 403 and return
rescue TransactionError => ex
render json: {error: ex.message}, status: 500 and return
end
render json: {balance: recipient_balance}
end

23. bonuscode.redeem(user)
или
user.redeem_bonuscode(code)
?

24. Service/Use case:
def redeem
use_case = RedeemBonuscode.new
begin
recipient_balance = use_case.run!(params[:code], params[:receptor_id])
rescue BonuscodeNotFound, BonuscodeIsAlreadyUsed, RecipientNotFound => ex
render json: {error: ex.message}, status: 404 and return
rescue IncorrectRecipientType => ex
render json: {error: ex.message}, status: 403 and return
rescue TransactionError => ex
render json: {error: ex.message}, status: 500 and return
end
render json: {balance: recipient_balance}
end

25. class RedeemBonuscode
def run!(hashcode, recipient_id)
raise BonuscodeNotFound.new unless bonuscode = find_bonuscode(hashcode)
raise RecipientNotFound.new unless recipient = find_recipient(recipient_id)
raise BonuscodeIsAlreadyUsed.new if bonuscode.used?
raise IncorrectRecipientType.new unless correct_user_type?(recipient.type)
ActiveRecord::Base.transaction do
amount = bonuscode.redeem!(recipient_id)
recipient.increase_balance!(amount)
recipient.save! && bonuscode.save!
end
recipient.balance
end
private
...
end

26. !---→-"---→----→----→----#

27. Incoming!!!
4 В таблице "users" по
факту хранятся разные
типы пользователей и
для них нужны разные
правила валидации
4 Это как минимум

28. Themis - modular and switchable
validations for ActiveRecord models
class User < ActiveRecord::Base
has_validation :admin, AdminValidation
has_validation :enduser, EndUserValidation
...
user.use_validation(:enduser)
user.valid? # => true
4 github.com/TMXCredit/themis

29. module EndUserValidation
extend Themis::Validation
validates_presence_of :username, :password, :email
validates :password, length: { minimum: 6 }
validates :email, email: true
end

30. !---→---"-→----→----→----#

31. Form objects (Inputs)
4 Plain old ruby objects*
class BonuscodeRedeemInput < Input
attribute :hash_code, String
attribute :receptor_id, Integer
validates_presence_of :hash_code, :receptor_id
validates_numericality_of :receptor_id
end

32. Form objects (Inputs)
class Input
include Virtus.model
include ActiveModel::Validations
class ValidationError < StandardError; end
def validate!
raise ValidationError.new, errors unless valid?
end
end

33. !---→----→---"-→----→----#

34. Incoming!
Заказчику нужен небольшой
сервис сбоку
mkdir sinatra-app
cd sinatra-app
git init .

35. class SenderApp < Sinatra::Base
get '/sms/create/:message/:number' do
input = MessageInput.new(params)
sender = TwilioMessageSender.new('xxxxxx', 'xxxxxx', '+15005550006')
use_case = SendSms.new(input, sender)
begin
use_case.run!
rescue ValidationError => ex
status 403 and return ex.message
rescue SendingError => ex
status 500 and return ex.message
end
status 201
end
end

36. Sinatra
4 встраивается в рельсовые роуты или
запускается в связке с другими rack-
приложениями
4 рельсовые роуты оказались ненужной
абстракцией
4 отчего бы не применить такой подход для
всего приложения?!

37. !---→----→----→--"--→----#

38. А как же разделение
бизнес-логики и
хранения данных?
4 Очень хочется но непонятно как
4 Репозитории?

39. Entities

40. Entities - зачем?
statuses profiles
-------- --------
id id
name status_id
profile.status.name

41. Entities
4 Plain old ruby objects*
class User < Entity
attribute :id, Integer
attribute :username, String
attribute :max_profiles, Integer, default: 3
attribute :profiles, Array[Profile]
attribute :roles, Array
end

42. Entities
4 Plain old ruby objects*
class Entity
include Virtus.model
def new_record?
!id
end
end

43. Repositories

44. Repositories - чем
занимаются?
4 найди мне объект с таким-то id
4 дай мне все объекты по такому-то
условию
4 сохрани вот эти данные в виде объекта

45. AR-flavored repositories
4 под капотом все те же ActiveRecord
модели
4 репозиторий отдает инстансы Entities

46. Первая попытка:
AR-flavored repositories
NEVER AGAIN!

47. Sequel FTW!
sequel.jeremyevans.net
4 DSL для построения SQL-запросов
4 реализация паттерна ActiveRecord

48. Repositories
def find(id)
dataset = table.select(:id, :username, :enabled,
:date_created, :last_updated).where(id: id)
user = User.new(dataset.first)
user.roles = get_roles(id)
user
end

49. Repositories
def find(id)
to_add = [:gender__name___gender, :profile_status__name___status,
:picture_id___image_id]
dataset = table.join(:profile_status, id: :profile_status_id)
.join(:gender, id: :profile__gender_id)
.select_all(:profile).select_append(*to_add)
.where(profile__id: id)
all = dataset.all.map do |record|
Profile.new(record)
end
all.size > 1 ? all : all.first
end

50. Repositories
def persist(profile)
status_id = DB[:online_profile_status].select(:id).where(name: profile.status).get(:id)
gender_id = DB[:gender].select(:id).where(name: profile.gender).get(:id)
hash = { username: profile.username,
profile_status_id: status_id,
gender_id: gender_id,
picture_id: profile.image_id }
if profile.new_record?
dates = { date_created: Time.now.utc, last_updated: Time.now.utc }
profile.id = table.insert(hash.merge! dates)
else
table.where(id: profile.id).update(hash)
end
end

51. Repositories
class ImageRepo
class ImageData < Sequel::Model
set_dataset DB[:image].join(:asset, asset__id: :image__asset_id)
many_to_many :images,
join_table: :image_image,
left_key: :image_id,
right_key: :image_images_id,
class: self
end
...

52. Benefits?

53. !---→----→----→----→---"-#

54. Presenters

55. class ProfilePresenter
def initialize(p, viewer)
...
def wrap!
hash = { id: p.id, deleted: p.deleted,
username: p.username, is_online: p.is_online }
hash[:user_id] = p.user_id if viewer.admin?
hash[:image] = p.image.to_hash if add_image?
hash
end
def self.wrap!(profiles, viewer)
profiles.map do |profile|
new(profile, viewer).wrap!
end
end
...
end

56. Presenters
post '/profile' do
begin
use_case = CreateProfile.new(current_user)
profile = use_case.run!(params)
rescue Input::ValidationError => ex
halt 403
end
wrapped_profiles = ProfilePresenter.wrap!([profile], current_user)
json(data: wrapped_profiles)
end

57. !---→----→----→----→----"#

58. Hexagonal/Clean
Architecture

60. From rails-way to
modular architecture
Ivan Nemytchenko,
independent consultant
DevConf 2014
@inem, @inemation