Ruby code explainers

ruby

class ArticlesController < ApplicationController
  before_action :set_article, only: %i[show edit update destroy publish]
 
  def edit

Policy-based authorization in a Rails controller

authorization policy-object before-action

Intermediate 9 steps

ruby

class ArticlesController < ApplicationController
  DEFAULT_LIMIT = 25
  MAX_LIMIT = 100

Cursor-based pagination in a Rails controller

pagination cursor query-building

Intermediate 7 steps

ruby

module ConfigMerge
  module_function
 
  def deep_merge(base, override)

Recursively merging nested config hashes in Ruby

recursion hash-merge immutability

Intermediate 8 steps

ruby

module DeepFreeze
  module_function
 
  def call(obj)

Recursively freezing nested Ruby data

recursion immutability pattern matching

Intermediate 9 steps

ruby

class Webhooks::StripeController < ApplicationController
  skip_before_action :verify_authenticity_token
  skip_before_action :authenticate_user!

How a Rails Stripe webhook controller works

webhooks signature verification event dispatch

Intermediate 7 steps

ruby

class ReportGenerator
  def initialize(account, period)
    @account = account
    @period = period

Memoized report metrics in Ruby in Rails

memoization query-composition service-object

Intermediate 7 steps

ruby

class PurgeStaleExportsJob < ApplicationJob
  queue_as :maintenance
 
  retry_on ActiveRecord::Deadlocked, wait: :polynomially_longer, attempts: 5

Purging stale exports with an Active Job in Rails

background-jobs batching error-handling

Intermediate 7 steps

ruby

class EmailValidator < ActiveModel::EachValidator
  EMAIL_FORMAT = /\A[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,}\z/i
 
  def validate_each(record, attribute, value)

Writing a custom email validator in Rails

validation regex custom validators

Intermediate 7 steps

ruby

class ConfigFlattener
  def initialize(config)
    @config = config
  end

Flattening nested config into dotted keys

recursion hashes tree-traversal

Intermediate 8 steps

ruby

def build_tree(rows, root_id: nil)
  children_by_parent = Hash.new { |hash, key| hash[key] = [] }
 
  rows.each do |row|

Building a tree from flat rows in Ruby

recursion hash-grouping tree-structure

Intermediate 5 steps

ruby

class MetricSeries
  def initialize(readings, window: 5)
    @readings = readings
    @window = window

Rolling averages with each_cons in Ruby

sliding-window enumerable data-smoothing

Intermediate 7 steps

ruby

class Api::V1::ArticlesController < Api::V1::BaseController
  def index
    articles = Article
      .published

Building a JSON:API endpoint in Rails

serialization eager-loading pagination

Intermediate 7 steps

ruby

class FundsTransfer
  class InsufficientFundsError < StandardError; end
 
  def initialize(source:, destination:, amount:)

Atomic money transfers with Rails transactions

service object database transactions row locking

Advanced 9 steps

ruby

class Money
  include Comparable
 
  CURRENCY_SYMBOLS = { usd: "$", eur: "€", gbp: "£" }.freeze

Building an immutable Money value object in Ruby

value-object immutability comparable

Intermediate 8 steps

ruby

require "csv"
 
class SalesReport
  def initialize(path)

Aggregating CSV sales data in Ruby

data-aggregation memoization group_by

Intermediate 6 steps

ruby

module DurationFormatter
  UNITS = [
    ['week', 604_800],
    ['day', 86_400],

Turning seconds into human-readable durations in Ruby

greedy-decomposition modular-arithmetic formatting

Intermediate 7 steps

ruby

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

Live-updating comments with Turbo in Rails

turbo-streams callbacks associations

Intermediate 8 steps

ruby

require 'json'
require 'set'
 
class SensitiveScrubber

Recursively scrubbing secrets from JSON

recursion data-masking pattern-matching

Intermediate 7 steps