Introduction to Rails - presented by Arman Ortega

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

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)

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"

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

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

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

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/

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

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:

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

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

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)
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

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

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

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!

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

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 routes
To run the app
C:railsappAPP_NAME> rails s

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

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'
. . .
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>

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

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

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

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

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

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

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)

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"

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

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

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

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/

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

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:

8/8/14 10
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

8/8/14 11
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

8/8/14 12
Installing Rails
For Windows
 Rails Installer 2.2.3 (http://railsinstaller.org/en)
Ruby
Rails
Bundler -manage your gem dependencies
Git
. . .
 XAMPP 1.8.2 (https://www.apachefriends.org/download.html)
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

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

8/8/14 14
Installing XAMPP on Windows

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

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!

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

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 is used for common administration tasks.
Sample rake commands are:
> rake db:migrate RAILS_ENV=development
> rake routes
To run the app
C:railsappAPP_NAME> rails s

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'
root 'welcome#index'
end

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'
. . .
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>

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

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

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

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

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

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Introduction to Rails - presented by Arman Ortega