This document discusses the Ruby programming language and the Rails web application framework. It provides an overview of Ruby's history and features such as blocks, closures, meta-programming and duck typing. It also summarizes Rails' MVC architecture, conventions over configuration approach, ActiveRecord ORM, associations, callbacks and validations. Rails controllers, routing, RESTful design and filters are briefly covered as well.

1. Ruby is Awesome
Vitaly Kushner
astrails.com

2. Interesting Times

3. Fast, Good, or Cheap.
Pick two.

4. Fast, Good, or Cheap.
Pick two.

5. Change Environment

6. Choose Language

7. Good Enough

8. You can do almost
anything
with any
language

9. http://www.flickr.com/photos/jantik/254695220/

10. Paul Graham
http://paulgraham.com/

11. Blub Language Paradox

12. BASIC was
“Good Enough”

13. No Recursion?!

14. Beating the averages
http://paulgraham.com/avg.html

15. Lisp is good

16. Ruby is Better!
:-)

17. Ruby is Practical

18. Ruby is an acceptable
LISP

19. History

20. History
• Yukihiro Matsumoto (aka "Matz")

21. History
• Yukihiro Matsumoto (aka "Matz")
• Released in 1993

22. History
• Yukihiro Matsumoto (aka "Matz")
• Released in 1993
• Got known in US about 2000

23. History
• Yukihiro Matsumoto (aka "Matz")
• Released in 1993
• Got known in US about 2000
• Gained momentum around 2003-2005

24. LISP
+
Smalltalk
+
Python
+
Perl

25. • Simple consistent syntax
• Dynamically typed
• Late binding
• Single Inheritance with Mixin support

26. • Everything is an object
• Closures
• Garbage Collection
• Multi platform

27. Ruby is Awesome

28. Blocks

29. array.each { |e| puts }
array.each { |e| puts e}
array.each do |e|
puts e
end

30. map {|x| ...}
collect {|x| ...}
select {|x| ...}
reject {|x| ...}
find {|x| ...}
any? {|x| ...}
all? {|x| ...}
sort {|a, b| ...}

31. File.readlines("foobar.dat").map{|l| l.strip}.sort {|x,y| x[-1] <=> y[-1]}.map {|x| x.upcase}.to_xml

32. File.readlines("foobar.dat").map{|l| l.strip}.sort {|x,y| x[-1] <=> y[-1]}.map {|x| x.upcase}.to_xml
File.readlines("foobar.dat")

33. File.readlines("foobar.dat").map{|l| l.strip}.sort {|x,y| x[-1] <=> y[-1]}.map {|x| x.upcase}.to_xml
File.readlines("foobar.dat")
.map {|line| line.strip}

34. File.readlines("foobar.dat").map{|l| l.strip}.sort {|x,y| x[-1] <=> y[-1]}.map {|x| x.upcase}.to_xml
File.readlines("foobar.dat")
.map {|line| line.strip}
.sort {|x,y| x.to_i <=> y.to_i}

35. File.readlines("foobar.dat").map{|l| l.strip}.sort {|x,y| x[-1] <=> y[-1]}.map {|x| x.upcase}.to_xml
File.readlines("foobar.dat")
.map {|line| line.strip}
.sort {|x,y| x.to_i <=> y.to_i}
.map {|x| x.upcase}

36. File.readlines("foobar.dat").map{|l| l.strip}.sort {|x,y| x[-1] <=> y[-1]}.map {|x| x.upcase}.to_xml
File.readlines("foobar.dat")
.map {|line| line.strip}
.sort {|x,y| x.to_i <=> y.to_i}
.map {|x| x.upcase}
.to_xml

37. class Hash
def to_html_attributes
map { |k, v|
k + '="' + v + '"'
}.join(' ')
end
end

38. attrs = {
:src => "foo.img",
:width => 100,
:height => 200,
:class => "avatar"
}
attrs.to_html_attributes
=> 'class="avatar" height="200" width="100" src="foo.img"'

39. Closures

40. class Array
def has_any_bigger_then(x)
any? {|e| e > x}
end
end

41. def incrementor(x)
proc {|y| y + x}
end
inc1 = incrementor(1)
inc5 = incrementor(5)

42. def incrementor(x)
proc {|y| y + x}
end
inc1 = incrementor(1)
inc1.call(1)
=> 2
inc1.call(3)
=> 4

43. def incrementor(x)
proc {|y| y + x}
end
inc5 = incrementor(5)
inc5.call(1)
=> 6
inc5.call(3)
=> 8

44. # ruby
def paidMore(amount)
proc {|e| e.salary > amount}
end
// C#
public Predicate<Employee>
PaidMore(int amount) {
return delegate(Employee e) {
return e.Salary > amount;
}
}

45. Meta Programming

46. Extending the language
to create new
abstractions

47. Monkey Patching

48. class Hash
def to_html_attributes
map { |k, v|
k + '="' + v + '"'
}.join(' ')
end
end

49. attrs = {
:src => "foo.img",
:width => 100,
:height => 200,
:class => "avatar"
}
attrs.to_html_attributes
=> 'class="avatar" height="200" width="100" src="foo.img"'

50. 3.megabytes
=> 3145728

51. 10.months.from_now
=> Thu Aug 12 03:25:40 0300 2010

52. 5.minutes.ago
=> Mon Oct 12 03:21:02 0200 2009

53. Duck Typing

54. .to_s
[1, 2, 3].to_s
=> "123"

55. .to_s
123.to_s
=> "123"

56. .to_s
"123".to_s
=> "123"

57. "a#{b}c"
"a" + b.to_s + c

58. method_missing

59. NoMethodError

60. User.find_by_company("Astrails")

61. User.find_by_name_and_company(
"Vitaly Kushner", "Astrails")

62. Multiple inheritance is evil
:-)

63. Modules
a.k.a. Mixins

64. module FlyHome
def set_home
@home = position
end
def fly_home
fly(@home)
end
end

65. class Bird < Living
include FlyHome
def fly(direction) ...
def position ...
end
class Airplane < Machine
include FlyHome
def fly(direction) ...
def position ...
end

66. DSL
Domain Specific Language

67. class User < ActiveRecord::Base
has_many :projects
belongs_to :account
has_many :reports,
:class_name => "User",
:foreign_key => :reports_to_id
named_scope :activated,
:conditions =>
"activated_at IS NOT NULL"
validates_uniqueness_of :name
validates_presence_of :crypted_password
validates_acceptance_of :terms_of_service
end

68. safe do
local { path "/backup/:kind" }
s3 :key => YOUR_S3_KEY,
:secret => YOUR_S3_SECRET,
:bucket => S3_BUCKET,
:path => ":kind/"
gpg :password => "foobar"
mysqldump do
options "-ceKq --single-transaction --create-options"
user "astrails"
password "foobar"
database :blog
database :astrails_com do
skip_tables :request_logs
end
end
tar do
archive "etc-files" do
files "/etc"
end
end
end

69. safe do
local { path "/backup/:kind" }
s3 :key => YOUR_S3_KEY,
:secret => YOUR_S3_SECRET,
:bucket => S3_BUCKET,
:path => ":kind/"
gpg :password => "foobar"
...
end

70. safe do
...
mysqldump do
options "-ceKq ..."
user "astrails"
password "foobar"
database :blog
database :astrails_com do
skip_tables :request_logs
end
end
...
end

71. safe do
...
tar do
archive "etc-files" do
files "/etc"
end
end
end

72. Rubygems

73. ➜ ~ ✗ sudo gem install astrails‐safe
Successfully installed astrails‐safe‐0.2.3
1 gem installed
Installing ri documentation for astrails‐safe‐0.2.3...
Installing RDoc documentation for astrails‐safe‐0.2.3...
➜ ~ ✗

74. Rubyforge.org
8,426 gems

75. Github.com
7,483 gems

76. Rails

77. http://www.flickr.com/photos/ecstaticist/2589723846/

78. Rails is Fun

79. optimized for
programmers happiness
and sustainable
productivity

80. MVC

81. MVC
• Model

82. MVC
•Model
• View

83. MVC
•Model
• View
• Controller

84. convention over
configuration

85. class User < ActiveRecord::Base
end

86. User.find(123)
=> SELECT * FROM `users` WHERE (`users`.`id` = 123)

87. class User < ActiveRecord::Base
belongs_to :account
has_many :projects
end
class UsersController < ApplicationController
def show
@user = User.find(params[:user])
render :template => 'show'
end
end

88. class User < ActiveRecord::Base
belongs_to :account
has_many :projects
end
class UsersController < ApplicationController
def show
@user = User.find(params[:user])
render :template => 'show'
end
end

89. class User < ActiveRecord::Base
belongs_to :account
has_many :projects
end
class UsersController < ApplicationController
def show
@user = User.find(params[:user])
end
end

90. Models

91. http://www.flickr.com/photos/slyadnev/3959052112/

92. ActiveRecord

93. ORM
Object-Relational Mapping

94. • MySQL
• PostgreSQL
• MSSql
• SQLite
• Oracle
• ODBC

95. Associations
class User < ActiveRecord::Base
has_many :projects
end
class Project < ActiveRecord::Base
belongs_to :user
end

96. u = User.find(1)
=> SELECT * FROM `users` WHERE (`users`.`id` = 1)

97. u.projects.count
=> SELECT count(*) AS count_all FROM `projects` WHERE
(`projects`.user_id = 1)

98. User.find_by_first_name("Vitaly", :include => :projects)
=> SELECT * FROM `users` WHERE
(`users`.`first_name` = 'Vitaly') LIMIT 1
=> SELECT `projects`.* FROM `projects` WHERE
(`projects`.user_id = 1)

99. Project.first.user
=> SELECT * FROM `projects` LIMIT 1
=> SELECT * FROM `users` WHERE (`users`.`id` = 1)

100. Callbacks
• before_validation
• before_validation_on_create
• after_validation
• after_validation_on_create
• before_save
• before_create
• after_create
• after_save

101. Callbacks
• before_validation
• before_validation_on_create
• after_validation
• after_validation_on_create
• before_save
• before_create
• after_create
• after_save

102. class User < ActiveRecord::Base
before_save :encrypt_password
attr_accessor :password
private
def enctypt_password
unless password.blank?
self.salt ||= ActiveSupport::SecureRandom.hex(40)
self.crypted_password = encrypt(password, salt)
end
end
end

103. Validations

104. validates_presence_of :account_id
validates_uniqueness_of :name
validates_numericality_of :ccv
def validate
unless name[0] == ?A
errors.add(:name, "Names must start with an A")
end
end

105. ActiveSupport

106. 3.days.ago
[1,2,3].to_json
2.weeks.from_now
hash.slice(:foo, :bar)

107. Controllers

108. http://www.flickr.com/photos/benjamin-nagel/2902721172/

109. class UsersController < ApplicationController
def index
@users = User.paginate(:page => params[:page],
:per_page => 20)
end
end

110. http://yourdomain/users/index

111. http://localhost:3000/users/index

112. ActionController::Routing::Routes.draw do |map|
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
end

113. ActionController::Routing::Routes.draw do |map|
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
end
/welcome/home
:controller => 'welcome'
:action => 'home'

114. ActionController::Routing::Routes.draw do |map|
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
end
/users/edit/123
:controller => 'users'
:action => 'edit'
:id => '123'

115. ActionController::Routing::Routes.draw do |map|
map.connect ':controller/:action/:id'
map.connect ':controller/:action/:id.:format'
end
projects/show/456.xml
:controller => 'projects'
:action => 'show'
:id => '456'
:format => 'xml'

116. /talks/create?title=ruby%20is%20awsome&author[name]=Vitaly&author[company]=Astrails
{
:controller => 'talks',
:action => 'create',
:title => "ruby is awesome",
:user => {
:name => 'Vitaly',
:company => 'Astrails'
}
}

117. REST

118. REST
Representational State Transfer

119. • HEAD
• GET
• POST
• PUT
• DELETE

120. • index
• edit
• new
• update
• create
• destroy
• show

121. index
GET /users

122. new
GET /users/new

123. create
POST /users

124. show
GET /users/123

125. edit
GET /users/123/edit

126. update
PUT /users/123

127. destroy
DELETE /users/123

128. map.resources :users do |user|
user.resources :projects
end
GET /users/123/projects
:controller => :projects, :action => :index, :user_id => 123
GET /users/123/projects/456
:controller => :projects, :action => :show, :user_id => 123, :id => 456

129. users_path
=> /users

130. new_user_path
=> /users/new

131. user_path(user)
=> /users/123

132. edit_user_path(user)
=> /users/123/edit

133. Filters

134. class UsersController < ApplicationController
before_filter :login_required,
:except => [:new, :create]
before_filter :find_user,
:only => [:edit, :show, :update, :destroy]
def index ...
def new ...
def create ...
def edit ...
def show ...
def update ...
def destroy ...
protected
def login_required ...
def find_user ...
end

135. class UsersController < ApplicationController
before_filter :login_required,
:except => [:new, :create]
...
protected
def login_required
unless session[:user_id]
redirect_to "/login"
end
end
end

136. class UsersController < ApplicationController
before_filter :find_user,
:only => [:edit, :show, :update, :destroy]
...
protected
def find_user
@user = User.find(params[:id])
end
end

137. def index
@users = User.paginate(
:page => params[:page], :per_page => 20)
end

138. def new
@user = User.new(params[:user])
end

139. def create
@user = User.new(params[:user])
if @user.save
flash[:notice] = "User created"
redirect_to user_path(@user)
else
flash.now[:error] = "Failed to create a user"
render :action => "new"
end
end

140. def edit
end

141. def show
end

142. def update
if @user.update_attributes(params[:user])
flash[:notice] = "User updated"
redirect_to user_path(@user)
else
flash.now[:error] = "Failed to update user"
render :action => "edit"
end
end

143. def destroy
if @user.destroy
flash[:notice] = "User deleted"
else
flash[:error] = "Failed to delete user"
end
redirect_to users_path
end

144. Errors

145. class UsersController < ApplicationController
before_filter :find_user,
:only => [:edit, :show, :update, :destroy]
...
def update
if @user.update_attributes(params[:user])
...
end
end
protected
def find_user
@user = User.find(params[:id])
end
end

146. ActiveRecord::RecordNotFound

147. HTTP 404

148. HTTP 500

149. Session

150. Session Store
• files
• database
• cookie

151. class UserSessionController < ApplicationController
def create
unless user = User.authenticate(
params[:login], params[:password])
flash.now[:error] = "Login failed"
render :action => :new
return
end
session[:user_id] = user.id
redirect_to user_path(user)
end
end

152. MVC

153. Views

154. http://www.flickr.com/photos/brapke/226101874/

155. def index
@users = User.paginate(
:page => params[:page], :per_page => 20)
end

156. app/views/users/index.html.erb

157. ERB
<p>
Hello <%= h(@user.name) %>
</p>

158. ERB
<ul>
<% @user.projects.each do |project| %>
<li><%= h(project.name) %></li>
<% end %>
<ul>

159. def index
@users = User.paginate(...)
respond_to do |format|
# default action is to render index.html.erb
format.html
format.xml { @users.to_xml }
format.json { @users.to_json }
end
end

160. HAML
%p
= @user.name
%ul
- @user.projects.each do |project|
%li= project.name

161. Testing

162. TDD

163. TDD
Test Driven Development

164. BDD

165. BDD
Behavior Driven Development

166. Pressure

167. TATFT

168. TATFT
Test All The Fucking Time

169. • Test::Unit
• RSpec
• Shoulda
• Cucumber
• Webrat

170. it "should be able to show media" do
@media = stub_media
Media.stub!(:find).and_return(@media)
get :show, :id => @media.id
response.should be_success
end

171. Migrations

172. class CreateProjects < ActiveRecord::Migration
def self.up
create_table :projects do |t|
t.integer :user_id, :null => false
t.string :title, :null => false
t.text :description, :null => false
t.integer :budget, :null => false
t.timestamps
end
end
def self.down
drop_table :projects
end
end

173. Plugins

174. inherited_resourfce
standard implementation for the 7 REST actions

175. acts_as_tree
db schema and methods for storing trees

176. country_select
HTML helper to present a select box of countries

177. Rails Scales?

178. http://www.flickr.com/photos/pinksherbet/223270526/

179. Rails Scales?
YES

180. LinkedIn’s “Bumper Sticker”
More then billion page views per month

181. if you have no
scalability problems
you are not growing fast enough!

182. Ruby is Awesome
Q &A
Vitaly Kushner
astrails.com