This document summarizes many of the new and improved features in Rails 3, including making Rails more modular by allowing alternative ORMs like DataMapper, improving performance by allowing parts of ActionController to be swapped out, introducing the Arel query assembly library and lazy loading, enhancing routing flexibility, and introducing the Bundler gem management tool. It also mentions changes to Javascript, plugins, and other features like ActiveModel and subscribers.

1. Rails 3
Cool New Things

2. * Caveats

3. Not ready...
● 3.0pre not released yet
● http://oscardelben.com/articles/2009/12/06/how­
to­test­rails­3.html

4. On to Cool Stuff...

5. Have It Your Way

6. More modular
● Standard Rails will work out of the box
● Swap AR with DataMapper
● http://www.slideshare.net/mattetti/rails3­
stepping­off­of­the­golden­path

7. .....

8. ActionController
● Based on Metal
● Swap out stuff you don't need for performance
● http://www.engineyard.com/blog/2010/rails­and­
merb­merge­plugin­api­part­3­of­6/

10. ActiveRecord & Arel

11. Arel
● compose queries using relational algreba (
http://github.com/rails/arel)
● Lazy loading in 3.1
(http://m.onkey.org/2010/1/22/active­record­
query­interface)

12. Arel
http://m.onkey.org/2010/1/22/active­record­query­interface

13. Responders
● respond_to now baked in
● Can make your own responders
● http://weblog.rubyonrails.org/2009/8/31/three­
reasons­love­responder

14.
http://www.engineyard.com/blog/2009/my­five­favorite­things­about­rails­3/

15. New Gem Bundler

16. Bundler
● No more config.gem
● Gemfile
● Evaluates all dependencies at once
● Deploying and freezing native gems !
● http://github.com/wycats/bundler

17. Gemfile

18. Config files *
● config/environment.rb shrunk
● New file : config/application.rb
● Application name seems to matter now
(https://rails.lighthouseapp.com/projects/8994/ti
ckets/3556­app_generator­should­disallow­or­
fix­invalid­app_const)

19. config/environment.rb

20. config/application.rb

21. config/boot.rb

22. Routing
More power to the people

23. Routing
● More flexible
● Can point to any Rack application
● “main#home == MainController.action(:home)
== a Rack application”
● http://yehudakatz.com/2009/12/26/the­rails­3­
router­rack­it­up/

24. Routing

25. Routing

26. ActionMailer
● Looks more like a Controller now
● http://gist.github.com/281420

27. ActionMailer
http://gist.github.com/281420

28. Javascript

29. Javascript
● Unobtrusive
● Easier to swap out with Jquery
● Uses HTML5 data­* attributes

30. Javascript

31. Plugins

32. Plugins
● rspec ­ http://github.com/dchelimsky/rspec­
rails/tree/rails3
● cucumber
http://blazingcloud.net/2010/01/17/notes­from­
rails­3­bugmash
● Others
http://wiki.rubyonrails.org/rails/version3/plugins_
and_gems

33. By the Way....

34. ActiveModel
Get Validations, etc by including
ActiveModel::Validations

35. Rails::Subscriber
● Get hooks for notifications, etc.
● E.g. Output ActiveRecord SQL to Growl
● http://hasmanyquestions.wordpress.com/2010/0
1/17/let­your­sql­growl­in­rails­3/

36. XSS protection
● eRB now escaped by default
● Use raw to not escape
● Try out the plugin
http://github.com/NZKoz/rails_xss

37. Starters
● http://omgbloglol.com/post/344792822/the­path­
to­rails­3­introduction
● http://www.engineyard.com/blog/2009/my­five­
favorite­things­about­rails­3/
● http://rails3.community­
tracker.com/permalinks/5/notes­from­the­field­
upgrading­to­rails­3