Roundup of what is on the web at regarding Rails 3 as of Easter 2010. Includes outline of significant changes to Rais in Rails 3 plus how you might set about upgrading an existing app. Acknowledges and links to to some amazing resources already elsewhere on the web.

1. Rails 3
(beta)
Roundup
April 6, 2010

2. Why Upgrade
• Performance
tighter & faster codebase, relational optimizations, shorter path to response, better scaling, better use of Rack & Middleware
• Security
better routing DSL, XSS protection, more powerful controller stack, better use of Rack & Middleware, fixes
• Labour-savings
easier routing, reliable gem management, easier Ajax, better code reuse, less monkey-patching, better & easier generators
• Modernization
Rack reliance, later Ruby, plug in new frameworks and components, new standards
• Cost saving
lower hardware requirements, less Gem maintenance, consistency means easier for developers

3. HTTP://GUIDES.RAILS.INFO/3_0_RELEASE_NOTES.HTML
Significant Features
• Dependency management with Bundler
• More concise router
• Chainable database query language
• New ActionMailer API
• Unobtrusive JavaScript
• Better modularity
• Improved XSS protection

4. Bundler
http://railscasts.com/episodes/201-bundler
get used to version juggling for now
gem "rails", "3.0.0.beta"
• all gems listed in # gem "rails", :git => "git://github.com/rails/
Gemfile rails.git"
gem "sqlite3-ruby", :require => "sqlite3"
• ‘setup’ gemfile # gem "rspec", :group => :test
group :test do
gem "webrat"
end
• ‘install’
gem install bundler
bundle setup
• ‘pack’ bundle install
bundle unlock
mate Gemfile
bundle install --without=test
• deploy app bundle pack
# application.rb
• unlock to modify require 'rails/all'
Bundler.require(:default, Rails.env) if defined?(Bundler)
Need version 9+. No config.gem required for Rails 3, although some need it for Rails 2.

5. New Modular
Architecture
• “Railties framework is now a set of individual Railties, each
inheriting from a new class, Rails::Railtie”
• Third-party plugins hook into early stages of initialization
• Rake tasks and generators part of the frameworks
• “In short, Rails frameworks are now plugins to Rails”
Action Mailer * Action Pack * Active Record *
Active Resource * Active Model * Active
Support
• And features like ActiveRecord validations and serialization
reusable, eg: include ActiveModel::Validations

6. Routing
resources :products do
• more concise get :detailed, :on => :member
end
block
resources :forums do
DSL collection do
get :sortable
put :sort
end
resources :topics
• rack routes end
match "/secret" => "info#about", :constraints => { :user_agent => /Firefox/ }
constraints :host => /localhost/ do
• constraints match "/secret" => "info#about"
match "/topsecret" => "info#about"
end
match "/hello" => proc { |env| [200, {}, "Hello Rack!"] }
• other features root :to => "home#index"
match "/about" => "info#about",
:as => :about

7. Controllers
• taller stack abstracting
rendering, layouts, rack, AbstractController::Base
etc
ActionController::Metal
• enhance by subclassing
New
relevant layer ActionController::Base
Old
• middleware layer ApplicationController
• ‘respond_with(@post)’ MyController
• flash[:notice] & flash[:alert]

8. ActionMailer
• like a controller r g mailer UserMailer welcome
gives...
• email types like
actions class UserMailer < ActionMailer::Base
def welcome(user, subdomain)
@user = user
• mail() to send @subdomain = subdomain
mail(:from => "admin@testapp.com",
:to => @user.email,
• no ‘deliver_’ prefix :subject => "Welcome to TestApp")
end
• mail() do..end for
end
multipart

9. More ActionMailer
class UserMailer < ActionMailer::Base
default :from => "admin@testapp.com"
def welcome(user, subdomain)
@user = user
@subdomain = subdomain
attachments['test.pdf'] = File.read("# {Rails.root}/public/test.pdf")
mail(:to => @user.email, :subject => "Welcome to TestApp") do |format|
format.html { render 'other_html_welcome' }
format.text { render 'other_text_welcome' }
end
end
end

10. More ActionMailer
class UserMailer < ActionMailer::Base
default :from => "admin@testapp.com"
def welcome(user, subdomain)
@user = user
@subdomain = subdomain
attachments['test.pdf'] = File.read("# {Rails.root}/public/test.pdf")
mail(:to => @user.email, :subject => "Welcome to TestApp") do |format|
format.html { render 'other_html_welcome' }
format.text { render 'other_text_welcome' }
end
end
end

11. Models
• New ActiveModel
MyClass
• Encapsulates ActiveModel::Validations
features
Serialization
ActiveModel::Observing
• ‘include’ in non-
ActiveModel::Serialization
ActiveRecords
etc..
• also...

12. Find and Scopes
• Relational algebra # Article.find(:all, :order => "published_at
desc", :limit => 10)
Article.order("published_at desc").limit(10)
• chained methods # Article.find(:all, :conditions => ["title = ?",
‘This’], :include => :comments)
Article.where("title = ?",
• named_scope now ‘This’).includes(:comments)
scope # Article.find(:first, :order => "published_at
desc")
Article.order("published_at").last
• conditions now # models/active_record.rb
scope :visible, where("hidden != ?", true)
where scope :published, lambda { where("published_at
<= ?", Time.zone.now) }
scope :recent, visible.published.order("published_at
desc")
• deferred retrieval

13. ActiveRelation Methods
• where • limit
• select • joins
• order • group
• offset • having
• includes • lock
• readonly
• from
Book.where(:author => "Austen").include(:versions).order(:title).limit(10)
Executed only when the data is needed

14. In Views
<%= form_for @product do |f| %>
• ‘=’ required for all tags <% end %>
that output content <%= div_for @product do %>
<% end %>
including blocks, like <% @comments.each do |c| %>
<% end %>
‘form_for’
<% content_for :side do %>
<% end %>
• ‘-’ no longer required <% cache do %>
<% end %>
to suppress spaces
<!-- products/show.html.erb -->
<%= admin_area do %>
• write_output_buffer <%= link_to "Edit", edit_product_path(@product) %> |
<%= link_to "Destroy", @product, :confirm => "Are you
sure?", :method => :delete %> |
method in helpers <%= link_to "View All", products_path %>
<% end %>
# application_helper.rb
• no ‘=’ for cache helper def admin_area(&block)
content = with_output_buffer(&block)
content_tag(:div, content, :class => "admin")
end

15. XSS Protection
• ‘h’ assumed
<!-- views/comments/_comment.html.erb -->
<div class="comment">
• new ‘raw’ method to %>
<%= strong link_to(comment.name, comment.url)
unescape <p><%= comment.content %></p>
</div>
# rails c
• html_safe? and "foo".html_safe?
safe = "safe".html_safe
safe.html_safe?
html_safe method to
# application_helper.rb
check/make string safe def strong(content)
"<strong>#{h(content)}</strong>".html_safe
end
• ‘html_safe’ must be
used on helper output

16. Unobtrusive Javascript
<!-- products/index.html.erb -->
<% form_tag products_path, :method => :get, :remote => true do
• Makes use of ‘data- %>
<p>
remote’ tag for Ajax forms <%= text_field_tag :search, params[:search] %>
<%= submit_tag "Search", :name => nil %>
</p>
<% end %>
• Other Javascript tag <a href="#" id="alert" data-message="Hello UJS!">Click Here</a>
‘data-’ attributes <%= link_to 'Destroy', post, :method => :delete %>
supported In rails.js
document.observe("dom:loaded", function() {
$(document.body).observe("click", function(event) {
• http://github.com/rails/ var message = event.element().readAttribute('data-confirm');
if (message) {
jquery-ujs }
// ... Do a confirm box
var element = event.findElement("a[data-remote=true]");
if (element) {
• http://github.com/rails/
// ... Do the AJAX call
}
var element = event.findElement("a[data-method]");
prototype_legacy_helper if (element) {
// ... Create a form
}
});

17. The Commandline
• rails s[erver] = start server
• rails c = start console
• rails g[enerate] = generate
Some new rake commands:-
• rake db:forward
• rake routes CONTROLLER=users

18. Generators
• All rewritten: http://www.viget.com/extend/rails-3-
generators-the-old-faithful
• More easily build new templates with Thor: http://
caffeinedd.com/guides/331-making-generators-for-
rails-3-with-thor
• RAILS_ROOT/lib/templates override generator
templates
• Rails::Generators::TestCase for testing generators
• _form partials and smart labels for form buttons

19. Extras
• config.filter_parameters << :password
• RAILS_ENV, RAILS_ROOT, etc.
• redirect_to(@user, :notice => ... )
• ‘validates :login, :presence =>
true, :length => { :minimum =>
4}, :inclusion => { :in => [1, 2, 3] }’

20. l18n
• I18n faster
• I18n on any object
• attributes have default translations
• Submit tags label automatically
• labels pass attribute name

21. Before Upgrading...
Note: Currently Beta2, so need to be brave/sure/low-impact
You will need/want:-
• www.railsupgradehandbook.com Jeremy McAnally
• http://github.com/rails/rails_upgrade
• RVM or other multi-ruby support
• Good test coverage (without factory_girl/shoulda?)
• Rails 3 hosting
• New git branch?

22. RVM
• Run any version of Ruby in its own environment
• Rails 3 needs at least 1.8.7 - Serious bugs in 1.9.1,
recommended version 1.9.2
• RVM lets you find best working one for you
• Installation instructions at:
• http://gist.github.com/296055
• http://railscasts.com/episodes/200-rails-3-beta-and-rvm
• no SUDO required

23. Update Check plugin
• http://github.com/rails/rails_upgrade
• Scan for changes to code, etc.
• Convert most routes automatically
• Create bundler Gemfile
• Back up important files
• Create starter configuration

24. The Rest of the Process
www.railsupgradehandbook.com Jeremy McAnally
• Regenerate the app
• Application.rb & environment.rb
• Check and tidy up routes manually
• Complete Gemfile manually
• Make all tests run
• Other Rails 3 enhancements (can be deferred)
• Host prepare and deploy (Heroku?)

25. Help & thanks
• http://www.railsupgradehandbook.com/ by Jeremy McAnally
• http://railscasts.com by Ryan Bates
• http://guides.rails.info/3_0_release_notes.html
• http://www.railsplugins.org/
• http://ruby5.envylabs.com/
• http://blog.envylabs.com/2010/02/rails-3-beautiful-code/ by Greg
Pollack
• http://weblog.rubyonrails.org/2010/4/1/rails-3-0-second-beta-release