Ruby & Rails Overview presented by Michal Poczwardowski on 11/05/15. Ruby is a dynamic, object-oriented language that is elegant and easy to read. Rails is a web application framework built on Ruby that follows conventions over configurations. It uses the MVC pattern with models, views, controllers, and routes to quickly develop powerful websites and applications. The presentation demonstrated core Ruby concepts and how to build a basic Rails application.

1. Ruby & Rails Overview
brought by Michal Poczwardowski and
Gdansk 11/05/15

2. Michal Poczwardowski
Ruby on Rails developer
michal.poczwardowski@netguru.co

3. Software house
web&mobile

4. Software house
web&mobile

5. Agenda
Part 1
ruby
Part 2
rails

6. Part 1
ruby

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

8. ‘Programming languages must feel
natural to programmers.’
Yukihiro "Matz" Matsumoto

10. hello = ‘Hello world!’
puts hello
Hello world

11. Try ruby in a browser!
tryruby.org

13. www.bloc.io/ruby-warrior
Control brave knight using ruby

15. Why ruby is so cool?

16. #1: puts ‘Yes’ if ‘Work’.starts_with? ‘W’
#2: population = 12_000_000
#3: misterious_number.between?(10, 20)
Like a natural language

17. def really?
true
end
Aesthetic

18. 1: numbers = []
2: for i in [1,2,3,4]
3: numbers << i ** 2
4: end
5: numbers # => [1,4,9,16]
Elegant - NON ruby-way solution

19. numbers = [1,2,3,4].map { |i| i ** 2 }
numbers # => [1,4,9,16]
Elegant - ruby-way solution

20. Everything is an object!

21. 42

22. 42.times { puts ‘Awesome’ }
Fixnum object

23. :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

24. Classes, objects
01: class School
02: attr_reader :name
03:
04: def initialize(name)
05: @name = name
06: end
07:
08: def hello
09: puts “Hello #{name}”
10: end
11: end
school = School.new(‘PG’)
school.hello
# => ‘Hello PG’

25. - high performance / lower level stuff
- multi-threading
- graphics / data analysis
Avoid ruby in case of

26. Ruby is great at...
Metaprogramming

27. Example with send
01: class Rubyist
02: def face(mood)
03: send(mood)
04: end
05:
06: private
07:
08: def happy
09: ‘:)’
10: end
11:
12: def sad
13: ‘:(‘
14: end
15: end
dev = Rubyist.new
dev.face(:happy)
# => ‘:)’
dev.face(:sad)
# => ‘:(’

28. Handle missing methods
1: class Rubyist
2: def happy; ‘:)’ end
3: def sad; ‘:(‘ end
4:
5: def method_missing(name)
6: ‘:?’
7: end
8: end
dev = Rubyist.new
dev.happy
# => ‘:)’
dev.sad
# => ‘:(’
dev.excited
# => ‘:?’
dev.worried
# => ‘:?’

29. Define own methods
01: class Rubyist
02: FACES = {
03: happy: ‘:)’,
04: sad: ‘:(’,
05: excited: ‘;D’,
06: angry: ‘:[‘
07: }
08:
09: FACES.each do |key, value|
10: define_method(key) { value }
11: end
12: end
dev = Rubyist.new
dev.happy
# => ‘:)’
dev.sad
# => ‘:(’
dev.angry
# => ‘:[’
dev.excited
# => ‘;D’

30. Everything changes
1: class String
2: def with_smile
3: self + ‘ :)’
4: end
5: end
‘Sad string’.with_smile
# => ‘Sad string :)’

31. ‘With great power comes great responsibility.’
Unkle Ben

32. Write tests!

33. Example rspec
describe Rubyist do
subject { described_class.new }
describe ‘#happy’ do
it ‘returns happy face’
expect(subject.happy).to eq ‘:)’
end
end
end

34. library -> gem

36. rubygems.org/stats - 9/05/15

37. 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 do
08: gem ‘rspec-rails’
09: end

38. Part 2
ruby on rails

39. Rails is a web application
development framework

40. ‘Powerful web applications that formerly might have
taken weeks or months to develop can be produced in
a matter of days.’
Tim O’Reilly

41. Websites powered by Rails

45. isitrails.com

46. Convention over
Configuration

47. Structure

48. controllers
models
views
routes.rb, database.yml
Gemfile

49. MVC

50. controller
model view
browser
DB
routes
web server

51. Let’s prepare some code

52. $ 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

53. 01: class CreatePosts < ActiveRecord::Migration
02: def change
03: create_table :posts do |t|
04: t.string :title
05: t.text :content
06:
07: t.timestamps
08: end
09: end
10: end
Migration

54. MVC in action

55. http://localhost:3000/

56. 127.0.0.1 - GET /index.html HTTP/1.0" 200 2326

57. get ‘/’, to: ‘welcome#index’

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

59. class Post < ActiveRecord::Base
end

61. class Post < ActiveRecord::Base
end

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

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

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

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

66. http://localhost:3000/

67. This is almost the end...

68. Don’t forget to visit
netguru.co
and our
box no. 20

69. Thanks!