Ruby Rails Overview

Ruby & Rails Overviewbrought by Michal Poczwardowski and

Gdansk 11/05/15

Michal PoczwardowskiRuby on Rails [email protected]

Software houseweb&mobile

Software houseweb&mobile

Agenda

Part 1

ruby

Part 2

rails

Part 1

ruby

Ruby is a dynamic, scripting, object-oriented language...

‘Programming languages must feel natural to programmers.’

Yukihiro "Matz" Matsumoto

hello = ‘Hello world!’puts hello

Hello world

Try ruby in a browser!

tryruby.org

www.bloc.io/ruby-warrior

Control brave knight using ruby

Why ruby is so cool?

#1: puts ‘Yes’ if ‘Work’.starts_with? ‘W’

#2: population = 12_000_000

#3: misterious_number.between?(10, 20)

Like a natural language

def really? trueend

Aesthetic

1: numbers = []2: for i in [1,2,3,4]3: numbers << i ** 24: end5: numbers # => [1,4,9,16]

Elegant - NON ruby-way solution

numbers = [1,2,3,4].map { |i| i ** 2 }

numbers # => [1,4,9,16]

Elegant - ruby-way solution

Everything is an object!

42

42.times { puts ‘Awesome’ }

Fixnum object

:001 > 1.class => Fixnum :002 > (2.2).class => Float :003 > [].class => Array :004 > "Politechnika Gdańska".class => String :005 > nil.class => NilClass :006 > {}.class => Hash

Output from irb

Classes, objects

01: class School02: attr_reader :name03: 04: def initialize(name)05: @name = name06: end07:08: def hello09: puts “Hello #{name}”10: end11: end

school = School.new(‘PG’)school.hello

# => ‘Hello PG’

- high performance / lower level stuff- multi-threading- graphics / data analysis

Avoid ruby in case of

Ruby is great at...

Metaprogramming

Example with send

01: class Rubyist02: def face(mood)03: send(mood)04: end05: 06: private07: 08: def happy09: ‘:)’10: end11:12: def sad13: ‘:(‘14: end15: end

dev = Rubyist.new

dev.face(:happy)# => ‘:)’

dev.face(:sad)# => ‘:(’

Handle missing methods

1: class Rubyist2: def happy; ‘:)’ end3: def sad; ‘:(‘ end4: 5: def method_missing(name)6: ‘:?’7: end8: end

dev = Rubyist.new

dev.happy# => ‘:)’

dev.sad# => ‘:(’

dev.excited# => ‘:?’

dev.worried# => ‘:?’

Define own methods

01: class Rubyist02: FACES = {03: happy: ‘:)’,04: sad: ‘:(’,05: excited: ‘;D’,06: angry: ‘:[‘07: }08: 09: FACES.each do |key, value|10: define_method(key) { value }11: end12: end

dev = Rubyist.new

dev.happy# => ‘:)’

dev.sad# => ‘:(’

dev.angry# => ‘:[’

dev.excited# => ‘;D’

Everything changes

1: class String2: def with_smile3: self + ‘ :)’4: end5: end

‘Sad string’.with_smile# => ‘Sad string :)’

‘With great power comes great responsibility.’Unkle Ben

Write tests!

Example rspec

describe Rubyist do subject { described_class.new }

describe ‘#happy’ do it ‘returns happy face’ expect(subject.happy).to eq ‘:)’ end endend

library -> gem

rubygems.org/stats - 9/05/15

Gemfile

01: source 'https://rubygems.org'02: 03: gem ‘rails’, ‘4.2.1’04: gem ‘nokogiri’05: gem 'stripe', git: 'https://github.com/stripe/stripe-ruby'06:07: group :test do08: gem ‘rspec-rails’09: end

Part 2

ruby on rails

Rails is a web application development framework

‘Powerful web applications that formerly might have taken weeks or months to develop can be produced in

a matter of days.’Tim O’Reilly

Websites powered by Rails

isitrails.com

Convention over Configuration

Structure

controllers

modelsviews

routes.rb, database.yml

Gemfile

MVC

controller

model view

browser

DB

routes

web server

Let’s prepare some code

$ rails generate model Post title:string content:text invoke active_record create db/migrate/20150509232514_create_posts.rb create app/models/post.rb invoke rspec create spec/models/post_spec.rb invoke factory_girl create spec/factories/posts.rb

Magic spells

01: class CreatePosts < ActiveRecord::Migration02: def change03: create_table :posts do |t|04: t.string :title05: t.text :content06: 07: t.timestamps08: end09: end10: end

Migration

MVC in action

http://localhost:3000/

127.0.0.1 - GET /index.html HTTP/1.0" 200 2326

get ‘/’, to: ‘welcome#index’

class WelcomeController < ApplicationController def index @posts = Post.all endend

class Post < ActiveRecord::Baseend

class Post < ActiveRecord::Baseend

class WelcomeController < ApplicationController def index @posts = Post.all endend

<ul> <% @posts.each do |post| %> <li> <%= post.title %> </li> <% end %></ul>

ERB

%ul - @posts do |post| %li =post.title

HAML

<html> … <body> … <%= yield %> … </body></html>

http://localhost:3000/

This is almost the end...

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Thanks!