Don't rewrite your framework

Have you ever seen someone rewriting the framework during a code review? After some time studying the Ruby on Rails documentation and doing some research on Reddit, I found some interesting features that are often not known by developers.

This talk was presented at TropicalRails 2025.

1. Vinícius B. Alonso Don’t rewrite your framework The lesser-known r a ils fe a tures
2. Who am I? • Vinícius Bail Alonso • Sr. Software Engineer • Master Degree Student at UTFPR
4. =
5. api.rubyonrails.org + reddit.com =
6. Context validations
7. class Customer < ApplicationRecord validates :name, :email, :password, :address_street, :address_city, presence: true end
8. class Customer < ApplicationRecord validates :name, :email, :password, :address_street, :address_city, presence: true end class Customer < ApplicationRecord validates :name, :email, :password, presence: true, on: :create validates :address_street, :address_city, presence: true, on: :account_finish end Validations in two di ff erent contexts
9. customer = Customer.new(name: 'John', email: 'john@google.com', password: '123') customer.valid? # => true customer.save # => true customer.valid?(:account_finish) # => false customer.save(context: :account_finish) # => false
10. customer.address_street = "1105 West Peachtree St" customer.address_city = "Atlanta" customer.valid?(:account_finish) # => true customer.save(context: :account_finish) # => true
11. Aggregations
12. class Customer < ApplicationRecord validates :name, :email, :password, :address_street, :address_city, presence: true end
13. https://martinfowler.com/bliki/ValueObject.html
14. class Address attr_reader :street, :city def initialize(street, city) @street = street @city = city end def ==(other) @street == other.street && @city == other.city end end
15. class Customer < ApplicationRecord composed_of :address, mapping: { address_street: :street, address_city: :city } end
16. customer = Customer.new customer.address_street = "123 Main St" customer.address_city = "Anytown" customer.address #<Address:0x0000ffffb045c6c0 @city="Anytown", @street="123 Main St">
17. customer = Customer.new customer.address_street = "123 Main St" customer.address_city = "Anytown" customer.address #<Address:0x0000ffffb045c6c0 @city="Anytown", @street="123 Main St"> address = Address.new("123 Main St", "Anytown") customer = Customer.new customer.address = address
18. customer = Customer.new customer.address_street = "123 Main St" customer.address_city = "Anytown" customer.address #<Address:0x0000ffffb045c6c0 @city="Anytown", @street="123 Main St"> address = Address.new("123 Main St", "Anytown") customer = Customer.new customer.address = address other_address = Address.new("456 Elm St", "Othertown") customer.address == other_address # false
19. customer = Customer.new customer.address_street = "123 Main St" customer.address_city = "Anytown" customer.address #<Address:0x0000ffffb045c6c0 @city="Anytown", @street="123 Main St"> address = Address.new("123 Main St", "Anytown") customer = Customer.new customer.address = address other_address = Address.new("456 Elm St", "Othertown") customer.address == other_address # false Customer.where(address: Address.new("123 Main St", "Anytown"))
20. Association Callbacks
21. class Cart < ApplicationRecord has_many :items end class Item < ApplicationRecord belongs_to :cart end
22. class Cart < ApplicationRecord has_many :items def update_total_price total_price = items.map(&:total_price).sum update(total_price: total_price) end end
23. class Cart < ApplicationRecord has_many :items, after_add: :increment_total_price, after_remove: :decrement_total_price def increment_total_price(item) self.total_price = item.total_price + total_price end def decrement_total_price(item) self.total_price = total_price - item.total_price end end
24. cart.items << item cart.update_total_price cart.items << item cart.save Before After
25. Batches
26. class ReportProcessorJob < ApplicationJob queue_as :default def perform(*args) Customer.all.each do |customer| ReportProcessor.new(customer).process end end end
27. class ReportProcessorJob < ApplicationJob queue_as :default def perform(*args) Customer.all.each do |customer| ReportProcessor.new(customer).process end end end 2 problems here: * Full table scan * All customers being loaded in memory at same time
28. class ReportProcessorJob < ApplicationJob queue_as :default def perform(*args) Customer.find_each do |customer| ReportProcessor.new(customer).process end end end
29. class ReportProcessorJob < ApplicationJob queue_as :default def perform(*args) Customer.find_in_batches do |batch| batch.each do |customer| ReportProcessor.new(customer).process end end end end
30. class ReportProcessorJob < ApplicationJob queue_as :default def perform(*args) Customer.find_in_batches(batch_size: 100) do |batch| batch.each do |customer| ReportProcessor.new(customer).process end end end end
31. Split 200 customers into two workers customers_ids = Customer.ids
32. Split 200 customers into two workers customers_ids = Customer.ids # Worker 1 Customer.find_in_batches(finish: customers_ids[99]) do |batch| batch.each do |customer| ReportProcessor.new(customer).process end end
33. Split 200 customers into two workers customers_ids = Customer.ids # Worker 1 Customer.find_in_batches(finish: customers_ids[99]) do |batch| batch.each do |customer| ReportProcessor.new(customer).process end end # Worker 2 Customer.find_in_batches(start: customers_ids[100]) do |batch| batch.each do |customer| ReportProcessor.new(customer).process end end
34. Optimistic Locking
35. class AddLockVersionToCustomers < ActiveRecord::Migration[7.0] def change add_column :customers, :lock_version, :integer end end
36. c1 = Customer.first c2 = Customer.first c1.address_street = "Fifth Avenue" c1.save # => true c2.address_street = "Abbey Road" c2.save # raises ActiveRecord::StaleObjectError
37. c1 = Customer.first c2 = Customer.first c1.address_street = "Fifth Avenue" c1.save # => true c2.reload c2.address_street = "Abbey Road" c2.save # => true
38. Pessimistic Locking
39. Customer.lock.find(1)
40. Customer.lock.find(1) Customer Load (7.3ms) SELECT "customers".* FROM "customers" WHERE "customers"."id" = $1 LIMIT $2 FOR UPDATE [["id", 1], ["LIMIT", 1]]
41. Customer.lock.find(1) Customer Load (7.3ms) SELECT "customers".* FROM "customers" WHERE "customers"."id" = $1 LIMIT $2 FOR UPDATE [["id", 1], ["LIMIT", 1]] Row-level lock
42. Customer.transaction do customer = Customer.lock.find(3) sleep(10) customer.address_city = "São Paulo" customer.save! end Customer.transaction do customer = Customer.lock.find(3) customer.address_city = "Curitiba" customer.save! end Process 1 Process 2
43. Process 1 Process 2 customers id address_city address_street 1 Curitiba Rua XV de Novembro 2 Rio de Janeiro Avenida Atlântica 3 Campinas Avenida Paulista
44. Process 1 Process 2 customers id address_city address_street 1 Curitiba Rua XV de Novembro 2 Rio de Janeiro Avenida Atlântica 3 Campinas Avenida Paulista Locks the row.
45. Process 1 Process 2 customers id address_city address_street 1 Curitiba Rua XV de Novembro 2 Rio de Janeiro Avenida Atlântica 3 Campinas Avenida Paulista Locks the row. Sleeps for 10 seconds
46. Process 1 Process 2 customers id address_city address_street 1 Curitiba Rua XV de Novembro 2 Rio de Janeiro Avenida Atlântica 3 Campinas Avenida Paulista Locks the row. Sleeps for 10 seconds P2 tries to select the row but the row is locked then it waits for P1
47. Process 1 Process 2 customers id address_city address_street 1 Curitiba Rua XV de Novembro 2 Rio de Janeiro Avenida Atlântica 3 São Paulo Avenida Paulista Locks the row Sleeps for 10 seconds P2 tries to select the row but the row is locked then it waits for P1 P1 updates and make row free
48. Process 1 Process 2 customers id address_city address_street 1 Curitiba Rua XV de Novembro 2 Rio de Janeiro Avenida Atlântica 3 Curitiba Avenida Paulista Locks the row Sleeps for 10 seconds P2 tries to select the row but the row is locked then it waits for P1 P1 updates and make row free P2 updates now
49. Normalize
50. class User < ApplicationRecord before_save :sanitize_fields private def sanitize_fields self.email = email.strip.downcase if email.present? self.phone = phone.delete("^0-9") if phone.present? end end
51. class User < ApplicationRecord normalizes :email, with: -> email { email.strip.downcase } normalizes :phone, with: -> phone { phone.delete("^0-9") } end
52. user = User.create(email: " CRUISE-CONTROL@EXAMPLE.COM\n") user.email # => "cruise-control@example.com" https://api.rubyonrails.org/classes/ActiveRecord/Normalization/ClassMethods.html
53. user = User.create(email: " CRUISE-CONTROL@EXAMPLE.COM\n") user.email # => "cruise-control@example.com" https://api.rubyonrails.org/classes/ActiveRecord/Normalization/ClassMethods.html User.exists?(email: "\tCRUISE-CONTROL@EXAMPLE.COM ") # => true User.exists?(["email = ?", "\tCRUISE-CONTROL@EXAMPLE.COM "]) # => false
54. user = User.create(email: " CRUISE-CONTROL@EXAMPLE.COM\n") user.email # => "cruise-control@example.com" https://api.rubyonrails.org/classes/ActiveRecord/Normalization/ClassMethods.html User.exists?(email: "\tCRUISE-CONTROL@EXAMPLE.COM ") # => true User.exists?(["email = ?", "\tCRUISE-CONTROL@EXAMPLE.COM "]) # => false User.normalize_value_for(:phone, "+1 (555) 867-5309") # => "15558675309"
55. Query methods
56. .extending module FilterByRole def only_admin where(role_name: :admin) end def only_manager where(role_name: :manager) end end
57. .extending module FilterByRole def only_admin where(role_name: :admin) end def only_manager where(role_name: :manager) end end User.extending(FilterByRole).only_admin SELECT "users".* FROM "users" WHERE "users"."role_name" = $1 [["role_name", "admin"]]
58. .extending module Pagination def page(number) # pagination code goes here end end scope = Model.all.extending(Pagination) scope.page(params[:page])
59. Instrumentation
60. def index @contacts = Contact.all end
61. def index ActiveSupport::Notifications.instrument('contacts', extra: :information) do @contacts = Contact.all end end
62. def index ActiveSupport::Notifications.instrument('contacts', extra: :information) do @contacts = Contact.all end end ActiveSupport::Notifications.subscribe('contacts') do |event| event.name # => "contacts" event.duration # => 7.537125000031665ms event.payload # => { extra: :information } event.allocations # => 556 (objects) end
64. ActiveSupport::Notifications.subscribe "process_action.action_controller" do |event| event.name # => "process_action.action_controller" event.duration # => 10 (in milliseconds) event.allocations # => 1826 event.payload # => {:extra=>information} Rails.logger.info "#{event} Received!" end
65. String Inquirer
66. Rails.env.production?
67. Rails.env.production? env = ActiveSupport::StringInquirer.new(‘production') env.production? # => true env.test? # => false
68. In fl ector
69. Rails.application.routes.draw do namespace :api do root "home#index" end end class API::HomeController < ApplicationController def index render plain: 'API Home' end end
71. ActiveSupport::Inflector.inflections(:en) do |inflect| inflect.acronym "API" end con fi g/initializers/in fl ections.rb
72. 'posts'.singularize # => "post" 'post'.pluralize # => "posts" 'x-men: the last stand'.titleize # => "X Men: The Last Stand" 'employee_salary'.humanize # => "Employee salary"
73. Draw
74. Rails.application.routes.draw do root "landing#index" namespace :admin do root "home#index" resources :contacts, only: [:index, :show, :destroy] end namespace :manager do root "home#index" resources :categories resources :products resources :tables resources :users end end
75. namespace :admin do root "home#index" resources :contacts, only: [:index, :show, :destroy] end namespace :manager do root "home#index" resources :categories resources :products resources :tables resources :users end con fi g/routes/admin.rb con fi g/routes/manager.rb
76. Rails.application.routes.draw do root "landing#index" draw :admin draw :manager end con fi g/routes.rb
77. Direct routes
78. Rails.application.routes.draw do # ... direct :docs do "https://docs.myapi.com" end direct :landing do { controller: 'landing', action: 'index', subdomain: 'www' } end end
79. rails console app.docs_url => "https://docs.myapi.com" app.landing_url => "http://www.example.com/"
80. Conclusion
81. The documentation is your best friend Everything in programming involves trade-o ff s. Make smart choices In this talk, there are a lot of uncovered features
82. Thank you!
83. Get in touch contato@viniciusalonso.com @alonsoemacao viniciusalonso
84. https://www.viniciusalonso.com/2025/04/01/tropicalrails-references.html References