rails

class CommentsController < ApplicationController
  before_action :set_post

  def create
    @comment = @post.comments.build(comment_params)

class Post < ApplicationRecord
  belongs_to :author, class_name: 'User'
  has_many :comments, dependent: :destroy

  scope :published, -> { where.not(published_at: nil).where('published_at <= ?', Time.current) }
  scope :draft, -> { where(published_at: nil) }

module Api
  module V1
    class UsersController < BaseController
      def show
        user = User.includes(:profile).find(params[:id])

class PostsController < ApplicationController
  def index
    @posts = Post.includes(:author)
                 .order(created_at: :desc)
                 .page(params[:page])
                 .per(10)

require "csv"

class PeopleCsvStream
  include Enumerable

  HEADERS = %w[id full_name email signed_up_at plan].freeze

<form data-controller="query-sync" data-action="change->query-sync#apply">
  <select name="status" class="rounded border p-2">
    <option value="">Any</option>
    <option value="open">Open</option>
    <option value="closed">Closed</option>
  </select>

class SignupForm
  include ActiveModel::Model
  include ActiveModel::Attributes

  attribute :account_name, :string
  attribute :email, :string

class TasksController < ApplicationController
  def destroy
    @task = Task.find(params[:id])
    @task.destroy!

    respond_to do |format|

Rails.application.configure do
  config.after_initialize do
    Bullet.enable = true
    Bullet.alert = false
    Bullet.bullet_logger = true
    Bullet.console = true

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