Introduction to Rails
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Introduction to Ruby on Rails Presented by: Arman Ortega rubyonrails.org
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Transcript of Introduction to Rails
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} " outend
say_hi "Michelle"
Interactive Ruby (irb)
irb(main):001:0> s = "Hello World" => "Hello World"irb(main):002:0> s.length => 11irb(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 => 5irb(main):007:0> n.class => Fixnumirb(main):008:0> 5.times { print s }Hello WorldHello WorldHello WorldHello WorldHello World
C:\Ruby193\bin>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 body1 hello world
Table: articles
a = Article.new
Object attribute
a.title
Convention over ConfigurationDatabase 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 textcreated_at datetimeupdated_at datetime
Table: articles
class Article < ActiveRecord::Base. . .end
File: models/article.rb
Class name FilenameUserController user_controller.rbStatusMessagesController status_messages_controller.rbRemoteUploader remote_uploader.rb
Another example:
Example:
CRUD: Create, Read, Update & DeleteCreate
example:a = Article.newa.title = "hello"a.body = "world"a.save
ReadModelClass.find(id)
example:Article.find(1)
ModelClass.where()example:Article.where("title = ?", "MH17")
m = ModelClass.newm.attribute = valuem.save
syntax:
More details: http://guides.rubyonrails.org/active_record_basics.html
CRUD: Create, Read, Update & DeleteUpdatem = ModelClass.find_by(field: value)m.attribute = valuem.save
example:a = Article.find_by(id: 1)a.title = "hello"a.body = "world"a.save
Deletea = 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 RailsFor Windows
Rails Installer 2.2.3 (http://railsinstaller.org/en)Packages included are:RubyRailsBundler -manage your gem dependenciesGit. . .
XAMPP 1.8.2 (https://www.apachefriends.org/download.html)Packages included are:Apache 2MySQL 5.6PHP 5phpMyAdmin. . .
For Linux, see the links below on how to install Rails on Linuxhttp://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 3How to verify the load path in Ruby?> ruby -e 'puts $:'C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/i386-msvcrtC:/RailsInstaller/Ruby1.9.3/lib/ruby/site_rubyC:/RailsInstaller/Ruby1.9.3/lib/ruby/vendor_ruby/1.9.1C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1/i386-mingw32
Installing Rails Installer on Windows
Installing XAMPP 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:\xampp\mysql\lib" --with-mysql-include="C:\xampp\mysql\include"'
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:\>xampp\mysql\lib) and paste it to C:\RailsInstaller2.2.3\Ruby1.9.3\bin
Sample Rails app (blog)
> rails new APP_NAME --database=mysqle.g. rails new blog --database=mysql
createcreate README.rdoccreate Rakefilecreate config.rucreate .gitignorecreate Gemfilecreate appcreate app/assets/javascripts/application.jscreate app/assets/stylesheets/application.csscreate app/controllers/application_controller.rbcreate app/helpers/application_helper.rbcreate app/views/layouts/application.html.erb. . .run bundle installFetching gem metadata from https://rubygems.org/...........Fetching additional metadata from https://rubygems.org/..Resolving dependencies...Using rake 10.3.2Using i18n 0.6.11Using activerecord 4.1.4Using 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 +-stylesheetsGemfileREADME.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:allRake 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 appC:\railsapp\APP_NAME> rails s
config/routes.rb
Rails.application.routes.draw doget '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/1In 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>
Running the app
'rails server' or 'rails s' command> rails s=> Booting WEBrick=> 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' commandrails generate controller <NAME> <action1> <action2> . . . e.g. > rails generate controller Welcome index
create app/controllers/welcome_controller.rb route get 'welcome/index‘invoke erbcreate app/views/welcomecreate app/views/welcome/index.html.erb. . .
> rails generate controller Articles add save edit updatecreate app/controllers/articles_controller.rb route get 'articles/update' route get 'articles/edit' route get 'articles/add'invoke erbcreate app/views/articlescreate app/views/articles/add.html.erbcreate app/views/articles/edit.html.erbcreate app/views/articles/delete.html.erb. . .
More info: http://guides.rubyonrails.org/command_line.html#rails-generate
Creating a Modelrails generate model <MODEL_NAME> <field1:type> <field2:type> . . .e.g.
> rails generate model Article title:string body:text invoke active_recordcreate db/migrate/20140705184622_create_articles.rbcreate app/models/article.rb. . .. . .
File: db/migrate/20140705184622_create_articles.rb
File: app/models/article.rb
Creating a viewsFile: 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
Thank you!
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} " outend
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 => 11irb(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 => 5irb(main):007:0> n.class => Fixnumirb(main):008:0> 5.times { print s }Hello WorldHello WorldHello WorldHello WorldHello World
C:\Ruby193\bin>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 body1 hello world
Table: articles
a = Article.new
Object attribute
a.title
8/8/14 9
Convention over ConfigurationDatabase 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 textcreated_at datetimeupdated_at datetime
Table: articles
class Article < ActiveRecord::Base. . .end
File: models/article.rb
Class name FilenameUserController user_controller.rbStatusMessagesController status_messages_controller.rbRemoteUploader remote_uploader.rb
Another example:
Example:
8/8/14 10
CRUD: Create, Read, Update & DeleteCreate
example:a = Article.newa.title = "hello"a.body = "world"a.save
ReadModelClass.find(id)
example:Article.find(1)
ModelClass.where()example:Article.where("title = ?", "MH17")
m = ModelClass.newm.attribute = valuem.save
syntax:
More details: http://guides.rubyonrails.org/active_record_basics.html
8/8/14 11
CRUD: Create, Read, Update & DeleteUpdatem = ModelClass.find_by(field: value)m.attribute = valuem.save
example:a = Article.find_by(id: 1)a.title = "hello"a.body = "world"a.save
Deletea = 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 RailsFor Windows
Rails Installer 2.2.3 (http://railsinstaller.org/en)Packages included are:RubyRailsBundler -manage your gem dependenciesGit. . .
XAMPP 1.8.2 (https://www.apachefriends.org/download.html)Packages included are:Apache 2MySQL 5.6PHP 5phpMyAdmin. . .
For Linux, see the links below on how to install Rails on Linuxhttp://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 3How to verify the load path in Ruby?> ruby -e 'puts $:'C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1C:/RailsInstaller/Ruby1.9.3/lib/ruby/site_ruby/1.9.1/i386-msvcrtC:/RailsInstaller/Ruby1.9.3/lib/ruby/site_rubyC:/RailsInstaller/Ruby1.9.3/lib/ruby/vendor_ruby/1.9.1C:/RailsInstaller/Ruby1.9.3/lib/ruby/1.9.1C:/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:\xampp\mysql\lib" --with-mysql-include="C:\xampp\mysql\include"'
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:\>xampp\mysql\lib) and paste it to C:\RailsInstaller2.2.3\Ruby1.9.3\bin
8/8/14 16
Sample Rails app (blog)
> rails new APP_NAME --database=mysqle.g. rails new blog --database=mysql
createcreate README.rdoccreate Rakefilecreate config.rucreate .gitignorecreate Gemfilecreate appcreate app/assets/javascripts/application.jscreate app/assets/stylesheets/application.csscreate app/controllers/application_controller.rbcreate app/helpers/application_helper.rbcreate app/views/layouts/application.html.erb. . .run bundle installFetching gem metadata from https://rubygems.org/...........Fetching additional metadata from https://rubygems.org/..Resolving dependencies...Using rake 10.3.2Using i18n 0.6.11Using activerecord 4.1.4Using 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 +-stylesheetsGemfileREADME.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 db:create:allRake 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 appC:\railsapp\APP_NAME> rails s
8/8/14 19
config/routes.rb
Rails.application.routes.draw doget '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
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/1In 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>
8/8/14 21
Running the app
'rails server' or 'rails s' command> rails s=> Booting WEBrick=> 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' commandrails generate controller <NAME> <action1> <action2> . . . e.g. > rails generate controller Welcome index
create app/controllers/welcome_controller.rb route get 'welcome/index‘invoke erbcreate app/views/welcomecreate app/views/welcome/index.html.erb. . .
> rails generate controller Articles add save edit updatecreate app/controllers/articles_controller.rb route get 'articles/update' route get 'articles/edit' route get 'articles/add'invoke erbcreate app/views/articlescreate app/views/articles/add.html.erbcreate app/views/articles/edit.html.erbcreate app/views/articles/delete.html.erb. . .
More info: http://guides.rubyonrails.org/command_line.html#rails-generate
8/8/14 23
Creating a Modelrails generate model <MODEL_NAME> <field1:type> <field2:type> . . .e.g.
> rails generate model Article title:string body:text invoke active_recordcreate db/migrate/20140705184622_create_articles.rbcreate app/models/article.rb. . .. . .
File: db/migrate/20140705184622_create_articles.rb
File: app/models/article.rb
8/8/14 24
Creating a viewsFile: 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
8/8/14 26
Thank you!
