This document provides an introduction to Ruby on Rails presented by Arman Ortega. It outlines what will be covered including an overview of Ruby and Rails, the concept of convention over configuration in Rails, and performing CRUD (create, read, update, delete) operations. It then demonstrates creating a sample blog application in Rails and provides links for additional learning resources.

1. Introduction to Ruby on Rails
Presented by: Arman Ortega
rubyonrails.org

2. What you'll learn
➔ Overview of Ruby
➔ Overview of Rails
➔ Convention over Configuration
➔ CRUD – Create, Read, Update & Delete
➔ Sample Rails app (Blog)
➔ Short Activity (railszombies.org)

3. Ruby is object oriented
 Everything is an object. Integers, Floats, Booleans, Strings, Arrays, Hash – all are objects.
 Ruby is simple, elegant & natural syntax
 Inspired by Perl, Python, LISP
 Less lines of code, higher productivity
In PHP:
function say_hi($name)
{
$out = "Hi $name ";
return $out;
}
say_hi("Michelle");
In Ruby:
def say_hi name
out = "Hi #{name} "
out
end
say_hi "Michelle"

4. Interactive Ruby (irb)
irb(main):001:0> s = "Hello World"
=> "Hello World"
irb(main):002:0> s.length
=> 11
irb(main):003:0> s.upcase
=> "HELLO WORLD"
irb(main):004:0> s.downcase
=> "hello world"
irb(main):005:0> s.downcase.reverse
=> "dlrow olleh"
irb(main):006:0> n = 2 + 3
=> 5
irb(main):007:0> n.class
=> Fixnum
irb(main):008:0> 5.times { print s }
Hello WorldHello WorldHello WorldHello
WorldHello World
C:Ruby193bin>irb
Provides a shell(command
prompt) for experimentation.
String method
String class
Fixnum class

5. Arrays - are ordered, integer-indexed collections of any
object. Indexing starts at 0, as in C or Java.
e.g. pet = Array.new or []
irb> pet = ["dog", "cat", "mouse"]
irb> pet.count
=> 3
irb> pet.index("cat")
=> 1
irb> pet[2]
=> "mouse"
Hashes - is a collection of key-value pairs.
e.g. style = Hash.new or {}
irb> style = { "font_size" => 10, "font_family" => "Arial" }
=> {"font_size"=>10, "font_family"=>"Arial"}
irb> style["font_size"]
=> 10
Arrays & Hashes

6. More about Ruby
http://tryruby.org – an interactive tutorial
https://www.ruby-lang.org/en/documentation

7. What is Rails?
 Rails is an open-source web framework that’s optimized for programmer
happiness and sustainable productivity.
 Less lines of code, higher productivity.
 It is an MVC web framework where Models, Views and Controllers are fully
integrated.
 Written in Ruby language.
http://rubyonrails.org/ https://www.ruby-lang.org/en/

8. Overview of Rails
 Convention over Configuration
 ActiveRecord
– is the M in MVC – the model.
– It is the Object/Relational Mapping (ORM) layer supplied with Rails.
It closely follows the standard ORM model such as:
* tables map to classes
* columns map to object attributes
* rows map to objects
id title body
1 hello world
Table: articles
a = Article.new
Object attribute
a.title

9. Convention over Configuration
Database Table - Plural with underscores separating words (e.g. articles, asset_images )
Model Class - Singular with the first letter of each word capitalized (e.g. Article, AssetImage)
Filenames are written in lowercase, with underscores separating each word.
id int(11)
title varchar(255)
body text
created_at datetime
updated_at datetime
Table: articles
class Article < ActiveRecord::Base
. . .
end
File: models/article.rb
Class name Filename
UserController user_controller.rb
StatusMessagesController status_messages_controller.rb
RemoteUploader remote_uploader.rb
Another example:
Example:

10. CRUD: Create, Read, Update &
Delete
Create
example:
a = Article.new
a.title = "hello"
a.body = "world"
a.save
Read
ModelClass.find(id)
example:
Article.find(1)
ModelClass.where()
example:
Article.where("title = ?", "MH17")
m = ModelClass.new
m.attribute = value
m.save
syntax:
More details: http://guides.rubyonrails.org/active_record_basics.html

11. CRUD: Create, Read, Update &
Delete
Update
m = ModelClass.find_by(field: value)
m.attribute = value
m.save
example:
a = Article.find_by(id: 1)
a.title = "hello"
a.body = "world"
a.save
Delete
a = ModelClass.find_by(field: value)
a.destroy
example:
a = Article.find_by(title:"hi")
a.destroy
m = ModelClass.find_by(field1:value,
field2: value)
m.update(field1: value1,
field2: value2)
m = Article.find_by(title: "lorem1",
body: "lorem1")
m.update(title: "lorem2",
body: "lorem2")
Alternative way

12. Installing Rails
For Windows
 Rails Installer 2.2.3 (http://railsinstaller.org/en)
Packages included are:
Ruby
Rails
Bundler -manage your gem dependencies
Git
. . .
 XAMPP 1.8.2 (https://www.apachefriends.org/download.html)
Packages included are:
Apache 2
MySQL 5.6
PHP 5
phpMyAdmin
. . .
For Linux, see the links below on how to install Rails on Linux
http://coding.smashingmagazine.com/2011/06/21/set-up-an-ubuntu-local-development-machine-for-ruby-on-rails/
http://www.computersnyou.com/1535/2013/03/installing-ruby-on-rail-on-ubuntu-with-rbenv-step-by-step/
https://help.ubuntu.com/community/RubyOnRails

13. Step 1 of 3 Step 2 of 3
Step 3 of 3
How to verify the load path in Ruby?
> ruby -e 'puts $:'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/i386-msvcrt
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby
C:/RailsInstaller/Ruby1.9.3/lib/ruby/vendor_ruby/1.9.1
C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1
C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/i386-mingw32
Installing Rails Installer on Windows

14. Installing XAMPP on Windows

15. Some common errors during setup
Problem:
Error installing mysql2: ERROR: Failed to build gem native extension.
Solution:
> gem install mysql2 -- '--with-mysql-lib="C:xamppmysqllib" --with-
mysql-include="C:xamppmysqlinclude"'
Problem:
Incorrect MySQL client library version! This gem was compiled for
5.6.16 but the client library is 5.5.27. (RuntimeError)
Solution:
You need to copy libmysql.dll from MySQL installation directory(e.g.
c:>xamppmysqllib) and paste it to
C:RailsInstaller2.2.3Ruby1.9.3bin

16. Sample Rails app (blog)
> rails new APP_NAME --database=mysql
e.g. rails new blog --database=mysql
create
create README.rdoc
create Rakefile
create config.ru
create .gitignore
create Gemfile
create app
create app/assets/javascripts/application.js
create app/assets/stylesheets/application.css
create app/controllers/application_controller.rb
create app/helpers/application_helper.rb
create app/views/layouts/application.html.erb
. . .
run bundle install
Fetching gem metadata from https://rubygems.org/...........
Fetching additional metadata from https://rubygems.org/..
Resolving dependencies...
Using rake 10.3.2
Using i18n 0.6.11
Using activerecord 4.1.4
Using bundler 1.6.2
. . .
Your bundle is complete!

17. Rails directory structure
+-app
| +-assets
| | +-images
| | +-javascripts
| | +-stylesheets
| +-controllers
| +-helpers
| +-mailers
| +-models
| +-views
+-config (database.yml, routes.rb, application.rb, etc)
+-db (migration files)
+-lib
+-log (log files used for debugging)
+-public (404.html, favicon.ico, robots.txt)
+-test
+-vendor (third-party javascripts/css like twitter-bootstrap or jquery )
+-images
+-javascripts
+-stylesheets
Gemfile
README.rdoc

18. config/database.yml
development:
adapter: mysql2
database: blog_dev
username: root
password:
host: localhost
test:
adapter: mysql2
database: blog_test
username: root
password:
host: localhost
production:
adapter: mysql2
database: blog_prod
username: root
password:
host: localhost
After configuring the database.yml. Then, let's create all databases
> rake db:create:all
Rake is used for common administration tasks.
Sample rake commands are:
> rake db:migrate RAILS_ENV=development
> rake db:create:all
> rake routes
To run the app
C:railsappAPP_NAME> rails s

19. config/routes.rb
Rails.application.routes.draw do
get 'articles/add', to: 'articles#add', as: 'articles_add'
get 'articles/:id', to: 'articles#details', as: 'articles_details'
get 'articles/:id/edit', to: 'articles#edit', as: 'articles_edit'
get 'articles/:id/delete', to: 'articles#delete', as: 'articles_delete'
post 'articles/save', to: 'articles#save', as: 'articles_save'
post 'articles/update', to: 'articles#update', as: 'articles_update'
get 'welcome/index', to: 'welcome#index', as: 'welcome_index'
root 'welcome#index'
end

20. Router
In controller:
def details
@article = Article.find params[:id]
end
The Rails router recognizes URLs and dispatches
them to a controller's action.
GET articles/1
In routes.rb
get '/articles/:id', to: 'articles#details', as: 'articles_details'
get 'welcome/index', to: 'welcome#index', as: 'welcome_index'
. . .
In views:
<div class="article">
<em><%= time_ago_in_words(@article.updated_at) %> ago</em>
<h3><%= @article.title %></h3>
<p><%= @article.body %></p>
<%= link_to "<<Back to Home", welcome_index_path %>
</div>

21. Running the app
'rails server' or 'rails s' command
> rails s
=> BootingWEBrick
=> Rails 4.1.4 application starting in development
on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Notice: server is listening on all interfaces
(0.0.0.0). Consider using 127.0.0.1 (--binding
option)
=> Ctrl-C to shutdown server

22. Creating a Controller
'rails generate' or 'rails g' command
rails generate controller <NAME> <action1> <action2> . . .
e.g. > rails generate controller Welcome index
create app/controllers/welcome_controller.rb
route get 'welcome/index‘
invoke erb
create app/views/welcome
create app/views/welcome/index.html.erb
. . .
> rails generate controller Articles add save edit update
create app/controllers/articles_controller.rb
route get 'articles/update'
route get 'articles/edit'
route get 'articles/add'
invoke erb
create app/views/articles
create app/views/articles/add.html.erb
create app/views/articles/edit.html.erb
create app/views/articles/delete.html.erb
. . .
More info: http://guides.rubyonrails.org/command_line.html#rails-generate

23. Creating a Model
rails generate model <MODEL_NAME> <field1:type> <field2:type> . . .
e.g.
> rails generate model Article title:string body:text
invoke active_record
create db/migrate/20140705184622_create_articles.rb
create app/models/article.rb
. . .
. . .
File: db/migrate/20140705184622_create_articles.rb
File: app/models/article.rb

24. Creating a views
File: views/articles/add.html.erb
More info: http://guides.rubyonrails.org/form_helpers.html

25. Useful links
 https://www.ruby-lang.org/en/documentation/
 http://guides.rubyonrails.org/getting_started.html
 http://tryruby.org
 http://railsforzombies.org

26. Thank you!

27. 8/8/14 1
Introduction to Ruby on Rails
Presented by: Arman Ortega
rubyonrails.org

28. 8/8/14 2
What you'll learn
➔ Overview of Ruby
➔ Overview of Rails
➔ Convention over Configuration
➔ CRUD – Create, Read, Update & Delete
➔ Sample Rails app (Blog)
➔ Short Activity (railszombies.org)

29. 8/8/14 3
Ruby is object oriented
 Everything is an object. Integers, Floats, Booleans, Strings, Arrays, Hash – all are objects.
 Ruby is simple, elegant & natural syntax
 Inspired by Perl, Python, LISP
 Less lines of code, higher productivity
In PHP:
function say_hi($name)
{
$out = "Hi $name ";
return $out;
}
say_hi("Michelle");
In Ruby:
def say_hi name
out = "Hi #{name} "
out
end
say_hi "Michelle"

30. 8/8/14 4
Interactive Ruby (irb)
irb(main):001:0> s = "Hello World"
=> "Hello World"
irb(main):002:0> s.length
=> 11
irb(main):003:0> s.upcase
=> "HELLO WORLD"
irb(main):004:0> s.downcase
=> "hello world"
irb(main):005:0> s.downcase.reverse
=> "dlrow olleh"
irb(main):006:0> n = 2 + 3
=> 5
irb(main):007:0> n.class
=> Fixnum
irb(main):008:0> 5.times { print s }
Hello WorldHello WorldHello WorldHello
WorldHello World
C:Ruby193bin>irb
Provides a shell(command
prompt) for experimentation.
String method
String class
Fixnum class

31. 8/8/14 5
Arrays - are ordered, integer-indexed collections of any
object. Indexing starts at 0, as in C or Java.
e.g. pet = Array.new or []
irb> pet = ["dog", "cat", "mouse"]
irb> pet.count
=> 3
irb> pet.index("cat")
=> 1
irb> pet[2]
=> "mouse"
Hashes - is a collection of key-value pairs.
e.g. style = Hash.new or {}
irb> style = { "font_size" => 10, "font_family" => "Arial" }
=> {"font_size"=>10, "font_family"=>"Arial"}
irb> style["font_size"]
=> 10
Arrays & Hashes

32. 8/8/14 6
More about Ruby
http://tryruby.org – an interactive tutorial
https://www.ruby-lang.org/en/documentation

33. 8/8/14 7
What is Rails?
 Rails is an open-source web framework that’s optimized for programmer
happiness and sustainable productivity.
 Less lines of code, higher productivity.
 It is an MVC web framework where Models, Views and Controllers are fully
integrated.
 Written in Ruby language.
http://rubyonrails.org/ https://www.ruby-lang.org/en/

34. 8/8/14 8
Overview of Rails
 Convention over Configuration
 ActiveRecord
– is the M in MVC – the model.
– It is the Object/Relational Mapping (ORM) layer supplied with Rails.
It closely follows the standard ORM model such as:
* tables map to classes
* columns map to object attributes
* rows map to objects
id title body
1 hello world
Table: articles
a = Article.new
Object attribute
a.title

35. 8/8/14 9
Convention over Configuration
Database Table - Plural with underscores separating words (e.g. articles, asset_images )
Model Class - Singular with the first letter of each word capitalized (e.g. Article, AssetImage)
Filenames are written in lowercase, with underscores separating each word.
id int(11)
title varchar(255)
body text
created_at datetime
updated_at datetime
Table: articles
class Article < ActiveRecord::Base
. . .
end
File: models/article.rb
Class name Filename
UserController user_controller.rb
StatusMessagesController status_messages_controller.rb
RemoteUploader remote_uploader.rb
Another example:
Example:

36. 8/8/14 10
CRUD: Create, Read, Update &
Delete
Create
example:
a = Article.new
a.title = "hello"
a.body = "world"
a.save
Read
ModelClass.find(id)
example:
Article.find(1)
ModelClass.where()
example:
Article.where("title = ?", "MH17")
m = ModelClass.new
m.attribute = value
m.save
syntax:
More details: http://guides.rubyonrails.org/active_record_basics.html

37. 8/8/14 11
CRUD: Create, Read, Update &
Delete
Update
m = ModelClass.find_by(field: value)
m.attribute = value
m.save
example:
a = Article.find_by(id: 1)
a.title = "hello"
a.body = "world"
a.save
Delete
a = ModelClass.find_by(field: value)
a.destroy
example:
a = Article.find_by(title:"hi")
a.destroy
m = ModelClass.find_by(field1:value,
field2: value)
m.update(field1: value1,
field2: value2)
m = Article.find_by(title: "lorem1",
body: "lorem1")
m.update(title: "lorem2",
body: "lorem2")
Alternative way

38. 8/8/14 12
Installing Rails
For Windows
 Rails Installer 2.2.3 (http://railsinstaller.org/en)
Packages included are:
Ruby
Rails
Bundler -manage your gem dependencies
Git
. . .
 XAMPP 1.8.2 (https://www.apachefriends.org/download.html)
Packages included are:
Apache 2
MySQL 5.6
PHP 5
phpMyAdmin
. . .
For Linux, see the links below on how to install Rails on Linux
http://coding.smashingmagazine.com/2011/06/21/set-up-an-ubuntu-local-development-machine-for-ruby-on-rails/
http://www.computersnyou.com/1535/2013/03/installing-ruby-on-rail-on-ubuntu-with-rbenv-step-by-step/
https://help.ubuntu.com/community/RubyOnRails

39. 8/8/14 13
Step 1 of 3 Step 2 of 3
Step 3 of 3
How to verify the load path in Ruby?
> ruby -e 'puts $:'
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/i386-msvcrt
C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby
C:/RailsInstaller/Ruby1.9.3/lib/ruby/vendor_ruby/1.9.1
C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1
C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/i386-mingw32
Installing Rails Installer on Windows

40. 8/8/14 14
Installing XAMPP on Windows

41. 8/8/14 15
Some common errors during setup
Problem:
Error installing mysql2: ERROR: Failed to build gem native extension.
Solution:
> gem install mysql2 -- '--with-mysql-lib="C:xamppmysqllib" --with-
mysql-include="C:xamppmysqlinclude"'
Problem:
Incorrect MySQL client library version! This gem was compiled for
5.6.16 but the client library is 5.5.27. (RuntimeError)
Solution:
You need to copy libmysql.dll from MySQL installation directory(e.g.
c:>xamppmysqllib) and paste it to
C:RailsInstaller2.2.3Ruby1.9.3bin

42. 8/8/14 16
Sample Rails app (blog)
> rails new APP_NAME --database=mysql
e.g. rails new blog --database=mysql
create
create README.rdoc
create Rakefile
create config.ru
create .gitignore
create Gemfile
create app
create app/assets/javascripts/application.js
create app/assets/stylesheets/application.css
create app/controllers/application_controller.rb
create app/helpers/application_helper.rb
create app/views/layouts/application.html.erb
. . .
run bundle install
Fetching gem metadata from https://rubygems.org/...........
Fetching additional metadata from https://rubygems.org/..
Resolving dependencies...
Using rake 10.3.2
Using i18n 0.6.11
Using activerecord 4.1.4
Using bundler 1.6.2
. . .
Your bundle is complete!

43. 8/8/14 17
Rails directory structure
+-app
| +-assets
| | +-images
| | +-javascripts
| | +-stylesheets
| +-controllers
| +-helpers
| +-mailers
| +-models
| +-views
+-config (database.yml, routes.rb, application.rb, etc)
+-db (migration files)
+-lib
+-log (log files used for debugging)
+-public (404.html, favicon.ico, robots.txt)
+-test
+-vendor (third-party javascripts/css like twitter-bootstrap or jquery )
+-images
+-javascripts
+-stylesheets
Gemfile
README.rdoc

44. 8/8/14 18
config/database.yml
development:
adapter: mysql2
database: blog_dev
username: root
password:
host: localhost
test:
adapter: mysql2
database: blog_test
username: root
password:
host: localhost
production:
adapter: mysql2
database: blog_prod
username: root
password:
host: localhost
After configuring the database.yml. Then, let's create all databases
> rake db:create:all
Rake is used for common administration tasks.
Sample rake commands are:
> rake db:migrate RAILS_ENV=development
> rake db:create:all
> rake routes
To run the app
C:railsappAPP_NAME> rails s

45. 8/8/14 19
config/routes.rb
Rails.application.routes.draw do
get 'articles/add', to: 'articles#add', as: 'articles_add'
get 'articles/:id', to: 'articles#details', as: 'articles_details'
get 'articles/:id/edit', to: 'articles#edit', as: 'articles_edit'
get 'articles/:id/delete', to: 'articles#delete', as: 'articles_delete'
post 'articles/save', to: 'articles#save', as: 'articles_save'
post 'articles/update', to: 'articles#update', as: 'articles_update'
get 'welcome/index', to: 'welcome#index', as: 'welcome_index'
root 'welcome#index'
end

46. 8/8/14 20
Router
In controller:
def details
@article = Article.find params[:id]
end
The Rails router recognizes URLs and dispatches
them to a controller's action.
GET articles/1
In routes.rb
get '/articles/:id', to: 'articles#details', as: 'articles_details'
get 'welcome/index', to: 'welcome#index', as: 'welcome_index'
. . .
In views:
<div class="article">
<em><%= time_ago_in_words(@article.updated_at) %> ago</em>
<h3><%= @article.title %></h3>
<p><%= @article.body %></p>
<%= link_to "<<Back to Home", welcome_index_path %>
</div>

47. 8/8/14 21
Running the app
'rails server' or 'rails s' command
> rails s
=> BootingWEBrick
=> Rails 4.1.4 application starting in development
on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Notice: server is listening on all interfaces
(0.0.0.0). Consider using 127.0.0.1 (--binding
option)
=>Ctrl-C to shutdown server

48. 8/8/14 22
Creating a Controller
'rails generate' or 'rails g' command
rails generate controller <NAME> <action1> <action2> . . .
e.g. > rails generate controller Welcome index
create app/controllers/welcome_controller.rb
route get 'welcome/index‘
invoke erb
create app/views/welcome
create app/views/welcome/index.html.erb
. . .
> rails generate controller Articles add save edit update
create app/controllers/articles_controller.rb
route get 'articles/update'
route get 'articles/edit'
route get 'articles/add'
invoke erb
create app/views/articles
create app/views/articles/add.html.erb
create app/views/articles/edit.html.erb
create app/views/articles/delete.html.erb
. . .
More info: http://guides.rubyonrails.org/command_line.html#rails-generate

49. 8/8/14 23
Creating a Model
rails generate model <MODEL_NAME> <field1:type> <field2:type> . . .
e.g.
> rails generate model Article title:string body:text
invoke active_record
create db/migrate/20140705184622_create_articles.rb
create app/models/article.rb
. . .
. . .
File: db/migrate/20140705184622_create_articles.rb
File: app/models/article.rb

50. 8/8/14 24
Creating a views
File: views/articles/add.html.erb
More info: http://guides.rubyonrails.org/form_helpers.html

51. 8/8/14 25
Useful links
 https://www.ruby-lang.org/en/documentation/
 http://guides.rubyonrails.org/getting_started.html
 http://tryruby.org
 http://railsforzombies.org

52. 8/8/14 26
Thank you!