Fighting Fat Models (Богдан Гусев)
•
0 likes•394 views
The document discusses techniques for dealing with "fat models" in Ruby on Rails applications. It argues that concerns are better than services for encapsulating business logic that belongs in models. Concerns allow models to have default behaviors while still supporting edge cases. The document also notes that the single responsibility principle is misleading, as real-world objects often have multiple related responsibilities. Well-designed models with concerns promote code reuse and testability over separated services.
Report
Share
Fighting Fat Models (Богдан Гусев)
- 9. $ wc -l app/models/* | sort -n | tail 532 app/models/incentive.rb 540 app/models/person.rb 544 app/models/visitor_offer.rb 550 app/models/reward.rb 571 app/models/web_hook.rb 786 app/models/site.rb 790 app/models/referral.rb 943 app/models/campaign.rb 998 app/models/offer.rb 14924 total Existing techniques
- 14. # move (1) User.create_from_facebook # to (2) UserService.create_from_facebook # or (3) FacebookService.create_user Organise services by process rather than object they operate on Otherwise at some moment UserService would not be enough
- 16. module CommentService def self.create(attributes) comment = Comment.create!(attributes) deliver_notification(comment) end end "Я знаю откуда что берется" Services don't provide default behavior
- 19. that we are focused on. Wikipedia Model is a best place for default behaviour MVC authors meant that
- 21. Hooks in models We create default behavior and our data is safe. Example: Comment can not be created without notification. class Comment < AR::Base after_create :send_notification
- 28. Service with options module CommentService def self.create( attrs, skip_notification = false) end
- 30. Because you didn't say you don't need it Hey model, create model without notification Ok Support parameter in model class Comment < AR::Base attr_accessor :skip_comment_notification after_create do unless self.skip_comment_notification send_notification end end end
- 34. Where are presenters? UserPresenter.new(user) # OR class User include UserPresenter end Trade an API for less methods in object
- 36. Example of Service implementation with wrapper More example at ActiveRecord source code class StiTools def self.run(from_model, to_model) new(from_model, to_model).perform end private def initialize(from_model, to_model) def perform shift_id_info
- 37. Datagrid Gem Example of collection wrapper https://github.com/bogdan/datagrid UsersGrid.new( last_request: Date.today, created_at: 1.month.ago..Time.now) class UsersGrid scope { User } filter(:created_at, :date, range: true) filter(:last_request_at, :datetime, range: true
- 38. Wrapping Data https://github.com/bogdan/furi u = Furi.parse( "http://bogdan.github.com/index.html") u.subdomain # => 'bogdan' u.extension # => 'html' u.ssl? # => false module Furi def self.parse(string)
- 39. Service usage is inconvinient because of validation Customer.has_many :purchases Purchase.has_many :ordered_items OrderItem.belongs_to :product ManualOrder.ancestors.include?( ActiveRecord::Base) # => false order = ManualOrder.new(attributes) if order.valid? order.save_all_those_records_at_once!
- 42. Use Concerns class Comment < AR::Base include CommentNotification include FeedActivityGeneration include Archivable end Rails default: app/models/concerns/* Attention!
- 45. in the universe that follows the SRP class Proton include Gravitation include ElectroMagnetism include StrongNuclearForce include WeekNuclearForce end Why man made things should?
- 49. Split model into Concerns class User < AR::Base
- 50. class User < AR::Base include FacebookProfile end # Hybrid Concern that provides # instance and class methods module FacebookProfile has_one :facebook_profile # simplified def connected_to_facebook? def self.register_from_facebook(attributes) Ex.1 User + Facebook has_one :facebook_profile => Model #register_user_from_facebook => Service
- 53. Model Services Presenters Concern Concern Concern Concerns Base Attributes Associations has_one
- 55. Datagrid Summary