ruby intro

Ruby ecosystem

改善

in 1993 by Yukihiro Matsumoto

PHILOSOPHY of RUBY

HUMANISTIC

Ruby is simple in appearance but is very complex inside just like our human body!

Everething is Object

	  0.class #=> Fixnum
	  /^reg/.class  #=> Regexp
	  (1..10).class #=> Range
	  MyClass.class #=> Class
	  Class.class #=> class
	  true.class #=> TrueClass
	  nil.class #=> NilClass
	  

Internal DSL

Migration.up do
 create_table 'users', inherits: 'stuff' do |t|
   t.string :login, not_null: true, unique: false
   t.date :bith_date
 end
end
	  

Internal DSL Implementation

class Migration
  class << self # class methods
    def up(&block)
      #we eval block in scope of this object (potentialy dangerous)
      instance_eval(&block)
      connection.execute( declarations.join(';'))
    end

    def declarations; @declarations ||=[]; end

    def create_table(name, opts={})
      t = Table.new(name, opts)
      yield t
      declarations<< t
    end
  end
end 

Internal DSL Implementation

class Table
  def initialize(name,opts)
    @name, @opts = name, opts
  end

  def column(name, type, opts={})
    opts.merge(name: name, type: type)
    (@columns ||= [])<< opts
  end

  def string(name,opt)
    columns name, 'varchar', opts
  end

  def date(name,opt)
    columns name, 'date', opts
  end

  def to_sql
   %Q[create table #{@name} (#{@columns.map{|k,opts| "#{k} #{opts[:type]}"}.join(',')})]
  end
end 

Operators as methods, method punctuation

class Point
  def initialize(x,y); @x, @y = x, y; end
  def [](coord)
    self.send(coord) if self.respond_to?(coord)
  end

  def +(pt)
    raise "Ups" unless pt.is_a?(Point)
    @x += pt.x
    @y += pt.y
  end
end

def pt(*args)
  Point.new(*args)
end

pt(1,2) + pt(2,1) #=> pt(3,3)

Classes body is active!

class Programmer
  if Time.now.monday?
    def monday_method
      "monday, monday"
    end
  end
end

ActiveRecord Validation DSL

class User < ActiveRecord::Base
  validates :email, present: true, unique: true
  has_many :groups
end

user = User.new(name: 'Admin')

unless user.save
  puts user.errors #=> ['Email is required']
end

user.groups #=> groups

Modules

module Loggable
  def log(message)
    logger.debug(message)
  end

  def profile(name)
    start = Time.now
    yield
    log("#{name}: #{Time.now - start} sec.")
  end
end

class Service < BaseService
  include Loggable

  def serve
    log("start job")
    profile "long operation" do
      #...
    end
  end
end

Ruby Installation

curl -L https://get.rvm.io | bash -s stable --ruby #install rvm
rvm install 2.0 #install ruby 2
rvm install 1.9.3
rvm install jruby

rvm use 2.0
#or create in your project .rvmrc file with required ruby

RubyGems.org: Manage gems

gem install rails
gem list
# *** LOCAL GEMS ***

# activesupport (3.2.11)
# builder (3.1.4)
# bundler (1.0.22 ruby)
# coderay (1.0.8)
# colorize (0.5.8)
# diff-lcs (1.1.3)
# expression_parser (0.9.0)
# github-markdown (0.5.3)
# github-markup (0.7.5)
# grit (2.5.0)
# huffshell (0.0.11)

gem update rails

Bundler: Manage Project Deps

gem install rails
gem install bundler

# Gemfile in root of your project
source "https://rubygems.org"
gem "nokogiri"
gem "rack", "~>1.1"
gem "rspec", :require => "spec"

bundle install
bundle update

Testing: Rspec; Factory Girl

#$ gem install rspec factory_girl or put it in your Gemfile

factory :user do
  name "John"
  email  "email"
end

describe User, "#score" do
  subject = { Factory.build(:user, email: nil) }
  it "validate email" do
    subject.validate
    subject.errors.should include(/email requried/)
  end
end

Testing: Capibara

#Capibara
it "signs me in" do
  visit '/sessions/new'
  within("#session") do
    fill_in 'Login', :with => 'user@example.com'
    fill_in 'Password', :with => 'password'
  end
  click_link 'Sign in'
  page.should have_content 'Success'
end

Automation: rake

#$ gem install rake
namespace :mydb do
  desc "dump db"
  task :dump do
    file = "/opt/backup/#{Time.now}.back"
    `pg_dump mydb > #{file} && rm #{/back/last} && ln /back/last #{file}`
  end

  desc "upload to s3"
  task :s3 do
    `s3cmd put /back/last s3://mycompany/back/last`
  end

  desc "maintain"
  task :default=>[:dump, :s3]
end

#$ rake -T
#$ rake mydb:s3

Rails: Web Dev that doesn't hurt

• generators
• MVC
• migrations
• rakes
• routing
• assets
• everething for your productivity

Rails: Generators

rails new myproject
echo 'gem "haml"' >> Gemfile
echo 'gem "simple_form"' >> Gemfile
echo 'gem "rspec"' >> Gemfile
echo 'gem "twitter_bootstrap"' >> Gemfile
bundle install

cd myproject
rake db:create
rails g controller wellcome index
rails g scaffold user name email bithdate:date
rake db:create db:migrate
rails s -p 80
chromium-browser http://localhost

Rails: Migrations

rails g migration create_users_with_groups
def up
  create_table 'users' do |t|
    t.string :email
    t.string :status
    t.string :password
  end

  create_table :participations do |t|
    t.timestamp :start_time
    t.references :user
    t.references :group
  end

  create_table 'groups' do |t|
    t.integer :owner
    t.string :name
  end

  add_index :users, :email
end

Rails: ActiveRecord

class User < ActiverRecord::Base
  validates :email, presense: true, uniqueness: true
  has_many :participations
  has_many :groups, through: :participations
  scope :active, -> { where(status: 'active' }
end

u = User.create(email: 'admin@m.io')
g = Group.create(name: 'admins')
u.groups<< g

User.active.include(:groups).order('email').each do |u|
  puts "#{u.email}"
  puts u.groups.map(&:name).join(', ')
end

Rails: Controllers

class UsersController < ApplicationController::Base
  before_filter :require_login

  respond_to :html, :xml, :json

  def index
    respond_with(@users = User.all)
  end

  def create
    @user = User.create(params[:user])
    respond_with(@user, :location => users_url)
  end

  private
  def require_login
    redirect_to login_path if current_user.nil?
  end
end

Rails: Routing

match "/patients/:id" => "patients#show"
resources :photos
resources :photos, :as => "images"
match '*pages' => 'pages#show', :format => true
namespace :admin do
  resources :posts, :comments
end

Rails: Views

%ul
  - @users.each do |user|
    %li.item= link_to user.name, user_path(user)

= simple_form_for (@quiz) do |f|
  = f.error_notification
  .inputs
    = f.input :body
    = f.fields_for :quiz_choices do |builder|
      = render "quiz_choice_fields", :f => builder
    %p= link_to_add_association  "Add a choice",f, :quiz_choices
  .actions
    = f.button :submit

RAILS: Assets

Coffee

jQuery ->
  $("#order_credit_card_number").blur ->
    if CreditCard.validNumber(@value)
      $("#credit_error").text("")
    else
      $("#credit_error").text("Invalid credit card number.")

Scss

a {
  color: $main-color;
  text-decoration: none;
  &:hover {
    text-decoration: underline;
  }
}

RAILS: tests/specs

• Unit Tests for Models and utils (FactoryGirl)
• Request Specs (Capibara + Selenium/Webkit)
• Mailers Specs
• Performance Tests

RAILS: deploy

• Capistrano
• Chef
• Heroku

RAILS: enginies plugins gems

• devise
• simple form
• act_as_{commentable, netsted_sets, statemachine, ...}
• twitter bootstrap, burbon, compas etc
• and more...

More about Rails

Google & Next time