Rails 2.3 : Dynamic Scopes

scoped_by_

Order.scoped_by_customer_id(12)
Order.scoped_by_customer_id(12).find(:all, :conditions => "status = 'open'")
Order.scoped_by_customer_id(12).scoped_by_status("open")

Ruby on Rails 2.3 Release Notes - 4.3 Dynamic Scopes

Rails 2.3 : Default Scopes

default_scope(options = {})

class Article < ActiveRecord::Base
  default_scope :order => 'created_at DESC'
end
Article.find(:all) #=> "SELECT * FROM `articles` ORDER BY created_at DESC"
Article.with_exclusive_scope { find(:all) } #=> "SELECT * FROM `articles`

Ruby on Rails 2.3 Release Notes - 4.4 Default Scopes
Class: ActiveRecord::Base

Rails 2.3 : Batch Processing

find_in_batches / find_each

Invoice.find_in_batches(:include => :invoice_lines) do |invoices|
  export.add_invoices(invoices)
end

User.find_each do |user|
  NewsLetter.weekly_deliver(user)
end

Ruby on Rails 2.3 Release Notes - 4.5 Batch Processing
Active Record Query Interface - 1.3 Retrieving Multiple Objects in Batches

Rails 2.3 : Object#try

you can avoid nil-checking

@person.try(:name) # @person ? @person.name : nil
@people.try(:collect) {|p| p.name}
Person.try(:find, 1)
Product.find_by_price(4.95).try(:name)

Ruby on Rails 2.3 Release Notes - 7.1 Object#try
Class: Object
Railscasts - Rails 2.3 Extras

rescue_from

Rescue exceptions raised in controller actions.

class ApplicationController < ActionController::Base
  rescue_from ActionController::RoutingError, :with => :route_not_found

  private
  def route_not_found(exception)
    render :text => exception.message.to_s, :status => :not_found
  end
end

has_many :bugs, :through => :rails: Rescue from dispatching
Module: ActiveSupport::Rescuable::ClassMethods
ヽ( ・∀・)ノくまくまー(2008-10-25) rescue_from (ActiveSupport::Rescuable)

Rails 2.2 : Memoization

Memoization is a pattern of initializing a method once and then stashing its value away for repeat use.

extend ActiveSupport::Memoizable

def full_name
  "#{first_name} #{last_name}"
end
memoize :full_name

Ruby on Rails 2.2 Release Notes - 9.1 Memoization
ヽ( ・∀・)ノくまくまー(2008-10-25) Memoization (ActiveSupport::Memoizable)

send_file

ファイルのダウンロード

send_file '/path/to.jpeg', :type => 'image/jpeg'

Module: ActionController::Streaming
画像やファイルをダウンロードさせる | メモ帳