Ruby on Rails 2.0: What's New, Release History & Support Lifecycle

What Is New in Ruby on Rails 2.0

How does Rails 2.0 enable RESTful routing and named routes?

Rails 2.0 introduces a declarative routing DSL that maps HTTP verbs to controller actions using the resources method.

• Define a resource once and get index, show, new, edit, create, update, destroy routes automatically.
• Named routes (named_route_path) replace manual URL strings, improving readability.

# config/routes.rb
ActionController::Routing::Routes.draw do |map|
  map.resources :articles
  map.login '/login', :controller => 'sessions', :action => 'new', :as => 'login'
end

In practice this means you can call articles_path for /articles and login_path for the login page, reducing hard-coded strings across the codebase.

What improvements were made to ActionMailer in Rails 2.0?

ActionMailer now supports full template rendering and multiple delivery methods out of the box.

• Mailers are regular Ruby classes inheriting from ActionMailer::Base.
• Views live under app/views/mailer_name and can be ERB or plain text.
• Delivery methods such as :smtp, :sendmail, and :test are configurable per environment.

# app/mailers/user_mailer.rb
class UserMailer < ActionMailer::Base
  default :from => "[email protected]"

  def welcome(user)
    @user = user
    mail(:to => @user.email, :subject => "Welcome")
  end
end

This matters if you need to send HTML and plain-text versions of the same email without writing custom MIME handling code.

How does Rails 2.0 enhance caching mechanisms?

Rails 2.0 adds built-in page and action caching to dramatically reduce response times for static-ish content.

• Page caching stores the full HTML output as a static file, bypassing the entire Rails stack on subsequent requests.
• Action caching runs filters but caches the rendered action, allowing per-user variations via cache_sweeper.
• Cache stores can be file-system or memory-based (memcached) with a simple configuration switch.

# config/environments/production.rb
config.action_controller.perform_caching = true
config.cache_store = :mem_cache_store, "localhost"

Watch out for stale content; you must expire caches manually or hook into model callbacks to sweep them.

What new ActiveRecord validation and callback features arrived in Rails 2.0?

Rails 2.0 introduces a richer set of validation helpers and lifecycle callbacks that simplify model integrity rules.

• New helpers: validates_presence_of, validates_numericality_of, validates_uniqueness_of.
• Conditional validations using :if and :unless options.
• Additional callbacks: before_validation, after_validation, around_save.

# app/models/post.rb
class Post < ActiveRecord::Base
  validates_presence_of :title, :body
  validates_numericality_of :rating, :only_integer => true, :greater_than => 0, :if => :published?

  before_validation :strip_whitespace
  def strip_whitespace
    self.title = title.strip unless title.nil?
  end
end

Most teams will find these helpers reduce custom validation code and make test suites more expressive.