breaking down Ruby on Rails parts and demistifying it

• Bundler
• Rake
  • Fantastic free course by Avdi Grim
• Rack
• ActiveSupport
• hash_with_indifferent_access gotchas
• ActiveRecord
  • basics
  • migrations
  • validations
  • callbacks
  • Associations
  • Query Interface
• ActiveModel
• ActiveMailer - running as standalone mailer
• ActiveJob
• others are too intertwined dependencies on the rest of rails to run individually - these are better run inside rails:
  • ActionCable,
  • ActionVeiew,
  • ActionController
• DSLs in rails/ruby - RSpec, Routes
• Routes: sinatra/hanami/Roda better for
• templates: ERB
• dissecting-rails book/site

Bundle

bundle exec [command]

bundle init # create Gemfile
bundle add [gemname] # it adds versions, so remove them if required
bundle remove [gemname]
bundle install

bundle show # show all gems in Gemfile
bundle show [gemname] # show path
bundle info [gemname]
bundle open [gemname] # open gem in editor

bundle console # open irb with gems loaded
# [DEPRECATED] bundle console will be replaced by `bin/console` generated by `bundle gem <name>`

Rake

free course by Avdi Grim

CLI docs

ri FileUtils

Basic FileList and script

create a basic Rakefile:

you need pandoc install, as it is used in the example

task default: :html

files = Rake::FileList.new('**/*.md') do |fl|
  fl.exclude(/^excluded_dir/)
end

task html: files.ext('.html')

rule '.html' => '.md' do |t|
  sh "pandoc -o #{t.name} #{t.source}"
end

Run it

rake
# or for debugging
rake --trace
# dump list of prerequisites
rake -P
# for quiet output
rake -q

you can add trace rules to your Rakefile to help with debugging:

Rake.application.options.trace_rules = true

List files

Rake::FileList.new('**/*')
  .pathmap("%f") # => ["README.md", "subdir", "ch1.md", "Rakefile"]
  .pathmap("%p") # => ["README.md", "subdir", "subdir/ch1.md", "Rakefile"]
  .pathmap("%n") # => ["README", "subdir", "ch1", "Rakefile"]
  .pathmap("%d") # => [".", "subdir", "subdir"]
  .pathmap("%x") # => ["md", "", "md", ""]
  .pathmap("%X") # => ["md", "", "md", ""]

Directory

directory 'ship_it🚢'

task list_files: 'ship_it🚢' do # dependency dir
  # ...

Cleaning generated files

task :clean do
  rm_rf 'ship_it🚢'
end

parallel execution

refer Rakefile in rake_sandbox/2_parallel dir

task single: files.ext('.html')
multitask parallel: files.ext('.html')

Rack

Minimalistic middleware / interfaces, that bridges between web servers, web frameworks, and web application into a single method call.

try building an app with Rack, you don't need a framework

# config.ru
run do |env|
  [200, { "some_header" => "lalala"}, ["Hello World"]]
end

gem install rack
rackup # starts your default web server on 9292
# or specify alternative webserver, i.e. 'webrick'
rackup -s webrick

curl -I http://127.0.0.1:9292

Active Support

docs

cd active_support
bundle install
bundle exec ruby bin/run

Core

• with_option
• try
• hash_with_indifferent_access
• presnece
• in?
• to_json is better implemented than JSON gem

3 Extensions to Module

• delegate and delegate_missing_to

4 Extensions to Class

• cattr_accessor
• descendants and subclasses

5 Extensions to String

• "".html_safe?
• squish
• singularize, pluralize, camelize / underscore, titleize / dasherize, demodulize, deconstantize, parameterize, humanize, constantize

"Hello World".remove(/Hello /) # => "World"

"Oh dear! Oh dear! I shall be late!".truncate(18, separator: ' ', omission: "🖖")) # =>  "Oh dear! Oh dear!🖖"
"Oh dear! Oh dear! I shall be late!".truncate_words(4)
# => "Oh dear! Oh dear!..."
o"foo".starts_with?("f") # => true
"foo".ends_with?("o")   # => true

<<HEREDOC.indent(2)
<<HEREDOC..strip_heredoc

'octopus'.pluralize
"equipment".singularize
"admin_user".camelize
"visual_effect".camelize(:lower) # => "visualEffect"
"visualEffect".underscore
"Admin::Hotel::ReservationUtils".demodulize # => "ReservationUtils"
"Admin::Hotel::ReservationUtils".deconstantize # => "Admin::Hotel"


"2010-07-27".to_date              # => Tue, 27 Jul 2010
"2010-07-27 23:37:00".to_time     # => 2010-07-27 23:37:00 +0200
"2010-07-27 23:37:00".to_datetime # => Tue, 27 Jul 2010 23:37:00 +0000

Time

1_235_551_234.to_fs(:phone, country_code: 61, area_code: true, extension: 555)
1_234_567_890.506.to_fs(:currency) # => $1,234,567,890.51
302.24398923423.to_fs(:percentage, precision: 5)
1_234_567_890_123.to_fs(:human_size) # => 1.12 TB
1_234_567_890.to_fs(:human) # => "1.23 Billion"
12_345_678.05.to_fs(:delimited, separator: ' ') # => 12,345,678 05

Formatting

1_235_551_234.to_fs(:phone, country_code: 61, area_code: true, extension: 555)
1_234_567_890.506.to_fs(:currency) # => $1,234,567,890.51
302.24398923423.to_fs(:percentage, precision: 5)
1_234_567_890_123.to_fs(:human_size) # => 1.12 TB
1_234_567_890.to_fs(:human) # => "1.23 Billion"
12_345_678.05.to_fs(:delimited, separator: ' ') # => 12,345,678 05
(Date.today..Date.tomorrow).to_fs(:db) # => "BETWEEN '2009-10-25' AND '2009-10-26'"

Conversions

%w(Earth Wind Fire).to_sentence # => "Earth, Wind, and Fire"

10 Extensions to Enumerable

• pluck
• pick
• many?
• index_by
• including / excluding
• exclude?

11 Extensions to Array

• extract

numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
odd_numbers = numbers.extract! { |number| number.odd? } # => [1, 3, 5, 7, 9]
numbers # => [0, 2, 4, 6, 8]

• similar to String/Enum methods, like to, from, third, excluding
• .in_groups_of

12 Extensions to Hash

• deep_merge / merge / deep_dup
• except
• symbolize_keys / stringify_keys

{ a: 1, b: 1 }.merge(a: 0, c: 2)
{ a: 1, b: 2 }.except(:a) # => {:b=>2}

13 Extensions to Regexp

%r{.}m.multiline? # => true

ActiveRecord

ActiveRecord is essentially ActiveModel with persistence layer

require 'active_record'

ActiveRecord::Base.establish_connection(
  adapter: 'sqlite3',
  database: 'sample.sqlite3'
)

---

class CreateUsers < ActiveRecord::Migration[6.0]
  def change
    create_table :users do |t|
      t.string :name
    end
  end
end

CreateUsers.new.migrate(:up)

---

class User < ActiveRecord::Base
  validates_presence_of :name, on: :create

  has_many :posts
end

---

• ActiveRecord
  • basics
  • migrations
  • validations
  • callbacks
  • Associations
  • Query Interface

 can't figure out what's causing a specific query in rails?

[look no further](https://www.mayerdan.com/ruby/2022/06/27/rails-query-tracing

module ActiveRecord
  class LogSubscriber < ActiveSupport::LogSubscriber
    def sql(event)
      # NOTE: I add a global $ignore_query == false && if I need to say ignore all the factories or before/after spec specific queries to help
      # only find callers in application code.
      if /FROM "some_table" WHERE "some_condition"/.match?(event.payload[:sql])
        Rails.logger.info "SQL FOUND #{caller_locations[15...150]}" 
        binding.irb if ENV["QUERY_BINDING"]
        # or
        # require 'awesome_print' 
        # ap caller if ENV["QUERY_BINDING"]
      end
    end
  end
end

ActiveRecord::LogSubscriber.attach_to :active_record

---

ActiveModel

 include ActiveModel::Model # similar to `ActiveRecord::Base`
  include ActiveModel::API # validation
   include ActiveModel::Validations
   extend ActiveModel::Translation # i18n gem integration
   include ActiveModel::Conversion # .persisted?

---

 extend ActiveModel::Callbacks # before_update :reset_me

 include ActiveModel::AttributeMethods # define meta attributes
  attribute_method_prefix 'reset_'
  define_attribute_methods 'age'
  def reset_attribute(attribute) = # your nobel prize logic

---

 include ActiveModel::Dirty # model.changed?

 include ActiveModel::Serialization
 include ActiveModel::Serializers::JSON

---

 include ActiveModel::SecurePassword
  has_secure_password
  attr_accessor :password_digest

---

ActionMailer

require 'action_mailer'
require 'letter_opener'

ActionMailer::Base.add_delivery_method :letter_opener, LetterOpener::DeliveryMethod, location: File.expand_path('../tmp/letter_opener', __FILE__)
ActionMailer::Base.delivery_method = :letter_opener

class LalaMailer < ActionMailer::Base
  def notify
    mail(
      to: 'ruby@australia.com',
      from: 'friendlyantz@pm.me',
      subject: 'Hello, World!'
    ) do |format|
      format.text { 'This is my text message' }
      format.html { '<h1>this is my html message</h1>' }
    end
  end
end

LalaMailer.notify.deliver_now

---