Rails勉強備忘録

知り合いがまとめてくれた記事。
http://qiita.com/runamoon@github/items/5277970364dca43b1204

ActiveRecord::Aggregations::ClassMethods

バリューオブジェクト関連のメソッド。

class Customer < ActiveRecord::Base
  composed_of :balance, class_name: "Money", mapping: %w(balance amount)
  composed_of :address, mapping: [ %w(address_street street), %w(address_city city) ]
end

ActionDispatch::Routing::Mapper::Concerns

concern :commentable do
  resources :comments
end

concern :image_attachable do
  resources :images, only: :index
end

resources :messages, concerns: [:commentable, :image_attachable]

ActiveModel::AttributeMethods::ClassMethods

alias_attribute(new_name, old_name)

class Person
  include ActiveModel::AttributeMethods

  attr_accessor :name
  alias_attribute :nickname, :name
end

person = Person.new
person.name = 'Bob'
person.name            # => "Bob"
person.nickname        # => "Bob"

ActiveRecord::Associations::ClassMethods

Polymorphic Associations の実装方法

class Asset < ActiveRecord::Base
  belongs_to :attachable, polymorphic: true
end

class Post < ActiveRecord::Base
  has_many :assets, as: :attachable
end

ActiveRecord::AttributeMethods::Serialization::ClassMethods

serialize のデフォルトはYAML

class User < ActiveRecord::Base
  serialize :preferences, JSON
end

class User < ActiveRecord::Base
  serialize :preferences, Hash
end

ActiveRecord::Store

serialize のラッパー。

class User < ActiveRecord::Base
  store :settings, accessors: [ :color, :homepage ], coder: JSON
end

ActiveRecord::Querying

find_by_sql の戻り値は配列

ActiveRecord::Batches

find_in_batches のオプションは batch_size と start

ActiveSupport::Testing::Assertions

assert_difference の書き方は3パターン

assert_difference 'Article.count' do
  post :create, article: {...}
end

assert_difference [ 'Article.count', 'Post.count' ], 2 do
  post :create, article: {...}
end

assert_difference ->{ Article.count }, 2 do
  post :create, article: {...}
end

Rails 固有のアサーション

• assert_difference
• assert_no_difference
• assert_recognizes
• assert_generates
• assert_response
• assert_redirected_to
• assert_template