Rails Intro & Tutorial

Ruby On Rails Intro & Tutorial

Mason Chang

Saturday, April 13, 13

Who I am?

• Mason Chang (張銘軒)

• Works at OptimisDev

• twitter: @changmason

• github: https://github.com/changmason


https://github.com/changmason

https://github.com/changmason

Part I


What is Rails?


Rails is...

http://rubyonrails.org/




Rails is...

• Created by DHH of 37signals in 2004

• Extracted from product Basecamp

• Of course, written in Ruby


Rails Philosophy


Don't Repeat Yourself

• Code generators

• Rake tasks

• Extentions


Code generators

• Generate new project

• Generate models

• Generate controllers & views


Rake tasks

• Run tests

• Manipulate database

• Show useful info


Extensions

• Sensible core extensions

• Helper methods

• A lot of 3rd party gems


Convention over Configuration(1)

• Convention for environments development, test and production

• Convention for organizing code

• Convention for organizing assets


Convention over Configuration(2)

• Convention for models model names - table names model attributes - record fields

• Convention for controllers & views controller actions - view templates


MVC Architecture


http://betterexplained.com/articles/intermediate-rails-understanding-models-views-and-controllers/




RESTful Routes


http://guides.rubyonrails.org/routing.html

Combine HTTP verb and path to dispatch requests to corresponding

handlers (actions)




A very simple blogin 5 minute


Part II


ActiveRecord & Model


What is ActiveRecord?

• ORM, Object-Relational Mapping

• Dealing with SQL

• A standalone Module

• Tons of functionalities


$ gem install activerecord $ irb

> require 'rubygems' > require 'active_record' > ActiveRecord::VERSION::STRING


ActiveRecord can connect to existing DB

> ActiveRecord::Base.establish_connection( :adapter => 'mysql2', :database => 'fju_test_db', :username => 'root', :password => '******' )

> ActiveRecord::Base.connection

> ActiveRecord::Base.connected?


ActiveRecord can migrate existing DB

> ARConnection = AR::Base.connection

> ARConnection.create_table(:users) do |t| t.string :name t.integer :age t.timestamps end

> ARConnection.add_index(:users, 'name')


ActiveRecord can execute raw SQL

> ARConnection = AR::Base.connection

> ARConnection.execute(%q{ INSERT INTO users (name, age) VALUES ('Mason Chang', 30) })

> resultes = ARConnection.execute(%q{ SELECT * FROM users WHERE age = 30 })> results.fields> results.first


User Model

> class User < ActiveRecord::Base end

> require 'logger'

> ActiveRecord::Base.logger = Logger.new(STDOUT)


Model can create records

> user.newser = User.new( :name => 'Eddie Kao', :age => 20)> user.save

> User.create( :name => 'Ryudo Teng', :age => 20)


Model can retrieve records

> User.first

> User.last

> User.all

> User.find(1)

> User.find([1,2,3])

> User.find(:first, :conditions => {:name => 'Eddie Kao'})

> User.find(:all, :conditions => ['age < ?', 30])


Model can update records

> user = User.find_by_name('Mason Chang')> user.age = 10> user.save

> user.update_attribute(:age, 20)

> user.update_attributes( :name => 'Ming-hsuan Chang' :age => 30)

> User.update(1, :age => 40)

> User.update_all( {:age => 50}, ['age >= ?', 20])


Model can delete records

> user = User.first

> user.delete # callbacks ignored

> user.destroy # callbacks triggered

> User.delete(1) # callbacks ignored

> User.destroy(1) # callbacks triggered


Model can do validations

> class User validates_presence_of :name validates_numericality_of :age end

> user = User.new(:age => 'thirty")

> user.save # fail

> user.errors.messages

http://guides.rubyonrails.org/active_record_validations_callbacks.html




Model can have callbacks

• Callbacks are operations which hooked into the lifecycle of an ActiveRecord object

• Object's lifecycle includes: creating, updating and destroying an object after initializing and finding an object





Callbacks for creating an object

• before_validation

• after_validation

• before_save

• around_save

• before_create

• around_create

• after_create

• after_save


Callbacks for updating an object

• before_validation

• after_validation

• before_save

• around_save

• before_update

• around_update

• after_update

• after_save


Callbacks for destroying an object

• before_destroy

• around_destroy

• after_destroy


Model can have associations

• One-to-one

• One-to-many

• Many-to-many

• and more...

http://guides.rubyonrails.org/association_basics.html




One-to-one association


One-to-many association


Many-to-many association


Part III


Task 0: Install Rails


$ gem install rails

$ rails --version


The rails command• create new project

> rails new [project_name]

• start server > rails server

• start console > rails console

• execute generator > rails generate [generator_type]

• more, and get help > rails help [command]


Task 1: New Project


$ rails new mylibrary --skip-test-unit

$ cd mylibrary/

$ rails server

$ rm public/index.html


Project Directory(1)


Project Directory(2)


Task 2: Install Some Gems & Import Specs


Gemfile: add haml-rails gem

$ bundle install

Gemfile: add rspec-rails

Gemfile: add capybara

$ bundle install

$ rails generate rspec:install

spec/spec_helper.rb: require 'capybara-rails'


Task 3: Create Book Model


$ rails generate model Book author:string title:string description:text publish_date:date

$ rake db:migrate

$ rails console

> Book.column_names


Task 4: Pass the "Create" Book Spec


Task 5: Pass the "Retrieve" Book Spec


Task 6: Pass the "Update" Book Spec


Task 7: Pass the "Destroy" Book Spec


Task 8: Refactor Routes


Task 9: Refactor Views


Task 10: Scaffold the Category


$ rails generate model Category name:string

$ rake db:migrate

$ rails console

> Category.column_names


Task 11: Apply Models' Associations


class Category < ActiveRecord::Base

has_many :books

end

class Book < ActiveRecord::Base

belongs_to :category

end


$ rails generate migration add_category_id_to_books category_id:integer:index

$ rake db:migrate


Task 12: Validate Inputs


class Book < ActiveRecord::Base

belongs_to :category

validates_presence_of :category_id,

:author,

:title

end


Task 13: Decorate with Twitter Bootstrap


Task 14: Deploy to Heroku


Assignments


Assignment 1: Add a search bar above the book list table on the index page, so the user can search for books by author name or by book title.


Assignment 2: Add pagination links below the book list table on the index page, so the user can browse through 20 books per page.


Technology

Rails Intro & Tutorial