Ruby (on Rails)

Jesen weba i dizajna

Elektrotehnički fakultet Osijek
12/12/12

Vlado Cingel
vlado@cingel.hr

Cingel d.o.o.

Čačinci

?

Freelancer

A person who sells services to employers without a long-term commitment to any of them

Ali to nije tema naše današnje emisije...

  • Ruby A programmer's best friend
  • Rack Minimal interface between webservers supporting Ruby and Ruby frameworks
  • Rails Web development that doesn't hurt

Ruby

Yukihiro Matsumoto

“matz”

1995

I wanted to design my own language to maximize my freedom
I wanted to design a language in which I could love programming

Matz

Sve je objekt

http://objectgraph.rubyforge.org/dotOG.html

I wanted a scripting language that was more powerful than Perl, and more object-oriented than Python 

5.times { print "Ruby" }

Ruby

  • Hello World!
  • Specifičnosti
  • RubyGems

Rack

Rack

Minimal interface between webservers supporting Ruby and Ruby frameworks

David Heinemeier Hansson

"dhh"

2003

Rails

Ruby on Rails is an open-source web framework that's optimized for programmer happiness and sustainable productivity. It lets you write beautiful code by favoring convention over configuration

Rails

  • puno posla sa malo koda
  • čini razvoj zabavnim
  • "tvrdoglav" framework

Rails Way

  • DRY Don't Repeat Yourself
  • Convention over configuration
  • REST Representational State Transfer

MVC arhitektura

Model, View, Controller

Model

  • prezentira podatke s kojima radite
  • primarno baza podataka (ali ne isključivo)
  • jedan model prezentira jednu tablicu u bazi
  • sav "business logic" nalazi se u modelima"

View

  • user interface (sučelje)
  • ERB templates najčešće
  • HTML, XML, JSON, JavaScript, ...

Controller

  • povezuje Model i View
  • web request -> dohvaća podatke -> prosljeđuje ih

Komponente

  • ActionPack
    • ActionController
      procesuira requestove, izvlači parametre i šalje ih akcijama koje ih trebaju, session management, render templejtova, redirekcije
    • ActionView
      odogovoran je za ispis, generira html, xml, json, ...
    • ActionDispatch
      odgovoran je za ruting web requestova i dispačiranje do aplikacije ili nekog drugog middlewarea
  • ActionMailer
    zadušen za generiranje i slanje mailova
  • ActiveRecord
    ORM adapter, database independent, CRUD funkcionalnost, napredni finderi, relacije između modela
  • ActiveResource
    definiranje modela iz RESTful web servisa
  • ActiveSupport
    skupina korisnih utility metoda i core extensiona
  • Railties
    core Rails code odogovran za dizanje aplikacije, povezuje ostale dijelove zajedno

Rails

primjer

ActiveRecord - Validations

Zadaća validacije


class Person < ActiveRecord::Base
end
          

p = Person.new(:name => "Vlado Cingel")
p.persisted? # false
p.save # true
p.persisted? # true

ActiveRecord - Validations

Kada se događa validacija?

  • create
  • create!
  • save
  • save!
  • update
  • update_attributes
  • update_attributes!

ActiveRecord - Validations

valid? / invalid?


class Person < ActiveRecord::Base
  validates :name, :presence => true
end
          

Person.create(:name => "Vlado Cingel").valid? # => true
Person.create(:name => nil).valid? # => false
          

Person.create(:name => "Vlado Cingel").invalid? # => false
Person.create(:name => nil).invalid? # => true

ActiveRecord - Validations

Errors


class Person < ActiveRecord::Base
  validates :name, :presence => true
end
          

p = Person.new
p.errors # {}
          

p = Person.create
p.errors # {:name=>["can't be blank"]}
p.errors[:name] # ["can't be blank"]

ActiveRecord - Validations

Helpers

ActiveModel::Validations::HelperMethods

+ Custom validations

ActiveRecord - Callbacks

Definiranje


class User < ActiveRecord::Base
  validates :login, :email, :presence => true

  before_create do |user|
    user.name = user.login.capitalize if user.name.blank?
  end
end

false ili exception otkazuju akciju i aktiviraju rollback

ActiveRecord - Callbacks

Novi objekt

  • before_validation
  • after_validation
  • before_save
  • around_save
  • before_create
  • around_create
  • after_create
  • after_save

ActiveRecord - Callbacks

Postojeći objekt

  • before_validation
  • after_validation
  • before_save
  • around_save
  • before_update
  • around_update
  • after_update
  • after_save

ActiveRecord - Callbacks

Brisanje objekta

  • before_destroy
  • around_destroy
  • after_destroy

ActiveRecord - Callbacks

Ostali

  • after_initialize
  • after_find
  • after_commit
  • after_rollback

ActiveRecord - Associations

Asociacija je veza između dva Active Record modela

Tipovi asocijacija

  • belongs_to
  • has_one
  • has_many
  • has_many :through
  • has_one :through
  • has_and_belongs_to_many

ActiveRecord - Associations

belongs_to

ActiveRecord - Associations

has_one

ActiveRecord - Associations

has_many

ActiveRecord - Associations

has_many :through

ActiveRecord - Associations

has_one :through

ActiveRecord - Associations

has_and_belongs_to_many

ActiveRecord - Associations

Polymorphic Associations

Model može pripadati (belongs_to) više nego jednom modelu

ActiveRecord - Query interface

Dohvat iz baze

Finder methods

  • where
  • select
  • group
  • order
  • reorder
  • reverse_order
  • limit
  • offset
  • joins
  • includes
  • lock
  • readonly
  • from
  • having

ActiveRecord - Query interface

Dohvat pojedinog objekta


Client.find(10)
# => SELECT * FROM clients WHERE (clients.id = 10) LIMIT 1

ActiveRecord - Query interface

Dohvat pojedinog objekta


Client.first
# => SELECT * FROM clients LIMIT 1

ActiveRecord - Query interface

Dohvat pojedinog objekta


Client.last
# => SELECT * FROM clients ORDER BY clients.id DESC LIMIT 1

ActiveRecord - Query interface

Dohvat više objekata od jednom


Client.find(1, 10)
# => SELECT * FROM clients WHERE (clients.id IN (1,10))

ActiveRecord - Query interface

Uvjeti - String


Client.where("orders_count = 2")
# => SELECT * FROM clients WHERE (orders_count = 2)

ActiveRecord - Query interface

Uvjeti - Array


Client.where("orders_count = ? AND locked = ?", 2, false)
# => SELECT * FROM clients WHERE (orders_count = 2 AND locked = 'f')
          

Client.where("orders_count = :count AND locked = :locked", {:count => 2, :locked => false})
# => SELECT * FROM clients WHERE (orders_count = 2 AND locked = 'f')

ActiveRecord - Query interface

Uvjeti - Hash


Client.where(:orders_count => 2)
# => SELECT * FROM clients WHERE (orders_count = 2)
          

Client.where(:orders_count => 2, :locked => false)
# => SELECT * FROM clients WHERE (orders_count = 2 AND locked = 'f')
          

Client.where(:orders_count => 2).where(:locked => false)
# => SELECT * FROM clients WHERE (orders_count = 2 AND locked = 'f')

ActiveRecord - Query interface

Uvjeti - Hash


Client.where(:created_at => (Time.now.midnight - 1.day)..Time.now.midnight)
# => SELECT * FROM clients WHERE (clients.created_at BETWEEN '2012-12-11 00:00:00' AND '2012-12-12 00:00:00')
          

Client.where(:orders_count => [1,3,5])
# => SELECT * FROM clients WHERE (clients.orders_count IN (1,3,5))

ActiveRecord - Query interface

Order


Client.order("created_at")
# => SELECT * FROM clients ORDER BY created_at
          

Client.order("orders_count ASC, created_at DESC")
# => SELECT * FROM clients ORDER BY orders_count ASC, created_at DESC

ActiveRecord - Query interface

Select


Client.select("viewable_by, locked")
# => SELECT viewable_by, locked FROM clients

ActiveRecord - Query interface

Limit, Offset


Client.limit(5)
# => SELECT * FROM clients LIMIT 5
          

Client.limit(5).offset(30)
# => SELECT * FROM clients LIMIT 5 OFFSET 30

ActiveRecord - Query interface

Joins


Client.joins('LEFT OUTER JOIN addresses ON addresses.client_id = clients.id')
# => SELECT clients.* FROM clients LEFT OUTER JOIN addresses ON addresses.client_id = clients.id

ActiveRecord - Query interface

Joins


class Category < ActiveRecord::Base
  has_many :posts
end

class Post < ActiveRecord::Base
  belongs_to :category
  has_many :comments
  has_many :tags
end

class Comment < ActiveRecord::Base
  belongs_to :post
  has_one :guest
end

class Guest < ActiveRecord::Base
  belongs_to :comment
end

class Tag < ActiveRecord::Base
  belongs_to :post
end
          

Category.joins(:posts)
# => SELECT categories.* FROM categories
  INNER JOIN posts ON posts.category_id = categories.id

ActiveRecord - Query interface

Joins - multiple associations


Post.joins(:category, :comments)
# => SELECT posts.* FROM posts
  INNER JOIN categories ON posts.category_id = categories.id
  INNER JOIN comments ON comments.post_id = posts.id

Joins - nested associations


Post.joins(:comments => :guest)
# => SELECT posts.* FROM posts
  INNER JOIN comments ON comments.post_id = posts.id
  INNER JOIN guests ON guests.comment_id = comments.id

ActiveRecord - Query interface

Joins - Conditions


time_range = (Time.now.midnight - 1.day)..Time.now.midnight
Client.joins(:orders).where('orders.created_at' => time_range)
Client.joins(:orders).where(:orders => {:created_at => time_range})

ActiveRecord - Query interface

Scopes


class Post < ActiveRecord::Base
  scope :published, where(:published => true)
end
          

Post.published
# => SELECT * FROM posts WHERE (published = 't')

ActiveRecord - Query interface

Scopes


class Post < ActiveRecord::Base
  scope :before, lambda { |t| where("created_at < ?", t) }
end
          

Post.before(Time.zone.now)

ActiveRecord - Query interface

Dynamic finders

  • find_by_*
  • find_first_by_*
  • find_last_by_*
  • find_all_by_*

Getting started

  • http://guides.rubyonrails.org/
  • http://railscasts.com

HVALA :)

vlado@cingel.hr