Ruby code explainers

ruby

module Api
  module Reports
    class DailyOrderTotalsController < Api::BaseController
      def index

Building a daily order totals report in Rails

sql aggregation json api query building

Intermediate 7 steps

ruby

module FixedWidthParser
  FIELDS = [
    { name: :record_type, range: 0...2 },
    { name: :account_id,  range: 2...12, type: :integer },

Parsing fixed-width records in Ruby

parsing data-driven-design type-coercion

Intermediate 5 steps

ruby

module Authenticatable
  extend ActiveSupport::Concern
 
  included do

JWT authentication as a Rails concern

authentication jwt concerns

Intermediate 6 steps

ruby

class Pipeline
  def initialize
    @middlewares = []
  end

Building a middleware pipeline in Ruby

closures middleware composition

Advanced 8 steps

ruby

class Contact < ApplicationRecord
  PHONE_FORMATS = {
    "US" => /\A\+1\d{10}\z/,
    "GB" => /\A\+44\d{10}\z/,

Country-aware phone validation in Rails

validation callbacks regex

Intermediate 6 steps

ruby

module AppConfig
  module_function
 
  def fetch(key, default: nil, required: false)

Typed environment variable config in Ruby

environment-variables type-coercion configuration

Intermediate 7 steps

ruby

class ThumbnailPool
  def initialize(worker_count: 4, capacity: 100)
    @queue = SizedQueue.new(capacity)
    @running = true

A thread pool for thumbnail jobs in Ruby

concurrency thread-pool bounded-queue

Advanced 7 steps

ruby

require "csv"
 
class CsvExporter
  def initialize(records, columns: nil)

Turning records into CSV in Ruby

csv data-export serialization

Intermediate 7 steps

ruby

class CircuitBreaker
  class OpenCircuitError < StandardError; end
 
  def initialize(failure_threshold: 5, reset_timeout: 30, half_open_max: 1)

How a circuit breaker guards failing calls

state-machine fault-tolerance concurrency

Advanced 9 steps

ruby

class ProjectsController < ApplicationController
  before_action :set_project, only: %i[show update destroy]
 
  def create

Scoping a Rails API controller to Current.account

multitenancy strong-parameters nested-attributes

Intermediate 7 steps

ruby

class SearchController < ApplicationController
  def index
    @query = params[:q].to_s.strip
  end

Live search suggestions in a Rails controller

controllers sql-injection query-building

Intermediate 6 steps

ruby

class TasksController < ApplicationController
  before_action :set_project
 
  def reorder

Bulk task reordering with upsert_all in Rails

bulk-update upsert authorization

Intermediate 8 steps

ruby

require "openssl"
require "json"
require "base64"

Building signed session tokens in Ruby

hmac authentication cryptography

Intermediate 8 steps

ruby

class Product < ApplicationRecord
  belongs_to :category, touch: true
 
  has_many :reviews, dependent: :destroy

How Rails models wire up associations

active record associations validations

Intermediate 7 steps

ruby

require "net/http"
require "json"
require "uri"
require "base64"

Paginating an HTTP API with a Ruby enumerator

pagination http enumerator

Intermediate 7 steps

ruby

class DateRangeMerger
  def initialize(ranges)
    @ranges = ranges
  end

Merging overlapping date ranges in Ruby

sorting interval-merging enumerable

Intermediate 5 steps

ruby

module SlowQueryLogger
  SLOW_QUERY_THRESHOLD_MS = 200.0
  IGNORED_PAYLOAD_NAMES = %w[SCHEMA TRANSACTION].freeze

Logging slow SQL queries in Rails

instrumentation logging pub-sub

Intermediate 7 steps

ruby

require "phonelib"
 
class PhoneNumber
  class InvalidNumber < StandardError; end

Wrapping phone parsing in a Ruby value object

value-object memoization validation

Intermediate 7 steps