Super fast ruby+rails intro.

1. Ruby && Rails && More
a fast-paced intro
Jean-Baptiste Feldis - @jbfeldis

2. @teacher =
Teacher.where(
:new => true,
:motivated => true,
:age => 27, # which *IS* still young
:username => «JB»,
:vouvoiement => «jamais»
)
@teacher.inspect

3. http://twitter.com/jbfeldis
http://studiomelipone.eu
http://freshfromthehive.com
http://upshotapp.com
http://card.biz
http://tumbulus.com
...

4. Todo List
1.Introduction ✔
2.Ruby
2.1.Basics
2.2.Syntax
2.3.More than scripts
3.Rails
4.Everything else
5.The Project

5. Ruby
Basics
1. http://www.ruby-lang.org/
2. Full Object Oriented
3. Created by Yukihiro “Matz“ Matsumoto in 1995
4. “Ruby is designed for programmer productivity and fun,
following the principles of good user interface design.”

6. Ruby
Syntax
Switching to IRB (Interactive RuBy)

7. Ruby
More Than Scripts
• for the web > Rails / Sinatra / ...
• for apps > JRuby (Java) / IronRuby (.NET) / MacRuby (Obj-C)

8. Todo List
1.Introduction ✔
2.Ruby ✔
3.Rails
3.1. Basics
3.2. MVC
3.3. Real life stuff
4.Everything else
5.The Project

9. Rails
Basics
1. http://rubyonrails.org/
2. Rails = web framework written in Ruby
3. Created by David Heinemeier Hansson (@dhh) from
37signals’ Basecamp app
4. First release July 2004
5. For web developpers by web developpers

10. Rails
Basics - Philosophy
1. Opinionated
2. Convention over con guration
3. DRY (Don’t Repeat Yourself )
4. TDD (Test Driven Development)

11. Get Ready!

12. Rails
Hello World - Needs
Rails is composed of a few commands:
- rails (to build your apps)
- gem (a ruby package manager to extend your code)
- bundle (a cool tool to manage your gems)
- rake (ruby gem to launch tasks)
More than that we need:
- a database (sqlite by default, included)
- a VCS (let’s use Git instead of Subversion)

13. Rails
Hello World - Rails
> rails new hello
This command generates code for
a new Rails web application
in a sub-directory called “hello”

14. Rails
Hello World - The App Directory
• the whole rails app is in this one directory
• no hidden con guration les in system directories
• you will modify many of these les in the course of your development
• if you use sqlite even the DB is in this directory
• in a dream world you could copy this to your server and go
party with your friends
• feeling bad about a «hello» app? Just delete the directory and
you’re done

15. Rails
Hello World - Environments
• rails is con gured with 3 environments (Rails.env):
• development: on your local computer, no caching
• test: env made to run tests
• production: for your real servers, caching and more
• database con g is in con g/database.yml
• speci c env con g to be in con g/environments/
development.rb, test.rb, production.rb

16. Rails
Hello World - One More Thing
• assets (like pictures, videos, .css, .js ...)
• static html les are in the public/ directory
• it’s the only directory exposed to the world, its content is
delivered before executing the app code
• new rails app come with an index.html le, remove that one
before launching your app (you can spend hours on that
one)

17. Rails
Hello World - Launch!
> cd hello
> bundle install
> rails server
open http://localhost:3000

18. Rails
MVC
1. High level design pattern: helps you structure your app
2. Model = Representation of your real life resources
3. View = Interface user interacts with
4. Controller = Responsible for app logic (get stuff, change
them, display the new state)

19. Takes Time And Efforts To
Get «Why» This Is So Cool.
Believe Me, Though, You Will.

20. Rails
MVC

21. Rails
MVC - Scaffold
Rails helps you setup your app with scaffolds.
> rails g scaffold person rst_name:string last_name:string
> rake db:migrate

22. Rails
MVC - Scaffold
Model
app/models/person.rb
db/migrate/20110512093227_create_people.rb
5 views
app/views/people/index.html.erb
app/views/people/show.html.erb
app/views/people/new.html.erb
app/views/people/edit.html.erb
app/views/people/_form.html.erb
Controller
app/controllers/people_controller.rb
routes.rb: resources : people

23. Rails
MVC

24. Rails
MVC - Model
Models inherit from ActiveRecord::Base.
Models are linked to database tables.
Gives us lots of amazing methods to nd...
People.all # nd all people in our database
People. rst # nd the rst record
People.where(:activated => true).limit(5).order(: rst_name) # nd 5 users ordered by rst name who are
activated
To populate...
@p = People.new
@p. rst_name = Buce
@p.last_name = Wayne
@p.save # returns true if everything’s okay
To modify
@p. rst_name = Bruce
@p.save
Or to curate
@p.delete

25. Rails
MVC - More Model
Okay, amazing stuff including automatic accessors. What more?
Validations:
validates_presence_of :email
validates_uniqueness_of :email, :scope => :agency_id
validates_length_of :email, :within => 6..100, :allow_nil => true, :allow_blank => true
Relations:
belongs_to :plan
has_many :orders
has_many :promo_codes
has_one :gui_data
Callbacks:
before_create, after_save...
Scopes
scope :published, lambda {
where("posts.published_at IS NOT NULL AND posts.published_at <= ?", Time.zone.now)
}
scope :published_since, lambda { |ago|
published.where("posts.published_at >= ?", ago)
}
scope :recent, published.order("posts.published_at DESC")

26. Rails
MVC - Views
Okay... So much to say...
display a variable in the code: <%= @var %>
First Name: <%= @person. rst_name %>
Content is escaped by default, if you need raw data use <%= raw @var %> or tell the view you data is
html_safe:
<%= @var.html_safe %>
You have conditional and loop statements available:
<% if @person.active? %>
Cool to see you again.
<% else %>
Please activate your account.
<% end %>
<% @people.each do |p| %>
First Name: <%= p. rst_name %>
<% end %>
Plus lots of helpers for forms, links, tags, text...

27. Rails
MVC - Controller - Routes
abstract literal URLs from code
the mapping between URLs and code, serves two purposes:
• recognize URLs and trigger a controller action
• generate URLs from names or objects, so you don’t have
to hard code them in views

28. Rails
MVC - Controller - Routes
follow REST (REpresentional State Transfer) pattern, so HTTP
verb are used to «act» upon ressources:
GET - to fetch
POST - to create
PUT - to update
DELETE - to... delete

29. Rails
MVC - Controller - Routes
In routes.rb you have: resources :people
> rake routes (remember this one)
people GET /people(.:format) {:action=>"index", :controller=>"people"}
people POST /people(.:format) {:action=>"create", :controller=>"people"}
new_person GET /people/new(.:format) {:action=>"new", :controller=>"people"}
edit_person GET /people/:id/edit(.:format) {:action=>"edit", :controller=>"people"}
person GET /people/:id(.:format) {:action=>"show", :controller=>"people"}
person PUT /people/:id(.:format) {:action=>"update", :controller=>"people"}
person DELETE /people/:id(.:format) {:action=>"destroy", :controller=>"people"}

30. Rails
MVC - Controller - Routes
Rails generates us 7 actions:
• index: list of all resources
• show: get speci ed resource
• new: get a form to create a new resource
• create: post data to create the new resource
• edit: get a form to update speci ed resource
• update: put data to update speci ed resource
• delete: delete speci ed resource

31. Rails
MVC - Controller - Routes
Let’s have a look at our PeopleController.rb

32. Rails
Real Life Stuff
(just to frighten you)

33. Todo List
1.Introduction ✔
2.Ruby ✔
3.Rails ✔
4.Everything else
4.1. Gem
4.2. Git
4.3. Heroku
5.The Project

34. Everything Else
Gem
http://rubygems.org
helps you extend your code with great code (thanks to ruby
and the great community behind ruby/rails)
> gem list
> gem install paperclip
use bundler, in Gem le:
gem «paperclip»
then > bundle (which is equivalent to « > bundle install»)

35. Everything Else
Git
http://git-scm.com and http://github.com
source version management IS TERRIBLY IMPORTANT
> git init .
> git status
> git add [ . | le | dir | -u ]
> git commit -v
> git branch new-branch
> git checkout new-branch
Git repo are local and can also be used remotely (in this case, you should
subscribe to Github)

36. Everything Else
Heroku
http://heroku.com
platform to deploy ruby apps «in the cloud»
> gem install heroku
> heroku create
> git push heroku master
> heroku logs
> heroku console

37. Todo List
1.Introduction ✔
2.Ruby ✔
3.Rails ✔
4.Everything else ✔
5.The Project

38. The Project
«It’s bloody hard to nd spare parts for your suit (or yourself ).
That would be so cool to have some kind of Amazon store to
get and sell them!»
Optimus Prime

39. The Project
Create a marketplace to buy and sell spare parts for
Transformers/Iron Man/Darth Vader.
• Create an account (buyer/seller)
• Post parts (price, quantity available...)
• Buy parts
• Administrate parts and users

40. The Project
Need to be online tomorrow (thank you Heroku). What you
will need (at least):
• Scaffolds
• Authentication (Devise)
• Roles (Cancan)
• File upload (Paperclip)
• Mails (Sendgrid)
For extra points: write tests (let’s say unit tests)

41. Thanks!
Questions?