ruby

import { Controller } from "@hotwired/stimulus"

export default class extends Controller {
  static targets = ["form"]
  static values = { delay: { type: Number, default: 250 } }

# app/mailers/user_mailer.rb
class UserMailer < ApplicationMailer
  default from: 'noreply@example.com'

  def welcome_email(user)
    @user = user

# BAD: N+1 query problem
@users = User.all
@users.each do |user|
  puts user.posts.count  # Fires query for each user!
end

json.array! @posts do |post|
  json.cache! ['v1', post], expires_in: 1.hour do
    json.id post.id
    json.title post.title
    json.excerpt post.excerpt
    json.published_at post.published_at

RegistrationSchema = Dry::Schema.Params do
  required(:email).filled(:string, format?: URI::MailTo::EMAIL_REGEXP)
  required(:password).filled(:string, min_size?: 12)
  optional(:marketing_opt_in).filled(:bool)
  optional(:country).filled(:string, included_in?: %w[US CA GB AU])
end

module ApplicationCable
  class Connection < ActionCable::Connection::Base
    identified_by :current_member

    def connect
      self.current_member = env['warden']&.user || reject_unauthorized_connection

class AddSettingsToAccounts < ActiveRecord::Migration[7.1]
  disable_ddl_transaction!

  def change
    add_column :accounts, :settings, :jsonb, null: false, default: {}

module EmailNormalization
  extend ActiveSupport::Concern

  included do
    attr_accessor :soft_warnings

class Comment < ApplicationRecord
  belongs_to :post, touch: true
  belongs_to :author, class_name: "User"

  validates :body, presence: true, length: { maximum: 10_000 }

import { Controller } from "@hotwired/stimulus"

export default class extends Controller {
  static values = {
    url: String,
    delay: { type: Number, default: 800 },

class Comment < ApplicationRecord
  belongs_to :article
  belongs_to :author, class_name: "User"

  validates :body, presence: true, length: { maximum: 2_000 }

# Installation
# rails active_storage:install
# rails db:migrate

# config/storage.yml
local: