This document summarizes the key new features in Rails 2.1, including time zone support, dirty tracking, gem dependencies, named scopes, UTC-based migrations, and improved caching. It provides examples of using each new feature and recommends additional resources for learning more. The major changes are time zone and dirty tracking functionality, easier gem management through dependencies, more powerful querying with named scopes, migration IDs that avoid conflicts, and enhanced caching configuration options.

1. What’s new in Rails 2.1?
Keith Pitty
Sydney Rails Meetup
11 June 2008

3. over 1,400 contributors

4. more than 1,600 patches

5. Major features
• Time zones
• Dirty tracking
• Gem dependencies
• Named scope
• UTC-based migrations
• Better caching

6. New!
Time zones
courtesy of Geoff Busing

7. $ rake -T time
(in /Users/keithpitty/work/rails2.1demo)
rake time:zones:all # Displays names of all time zones recognized by the...
rake time:zones:local # Displays names of time zones recognized by the Rai...
rake time:zones:us # Displays names of US time zones recognized by the ...

8. $ rake time:zones:local
* UTC +10:00 *
Brisbane
Canberra
Guam
Hobart
Melbourne
Port Moresby
Sydney
Vladivostok

9. # config/environment.rb
config.time_zone = 'Sydney'

10. Times now stored in UTC in the db
but displayed using the default time zone

11. Warning!
If upgrading, times will need to be converted to UTC

12. Example
Add time zone support to users

13. Add time_zone to User model

14. Add time_zone_select to signup view

15. <h1>Sign up as a new user</h1>
<% @user.password = @user.password_confirmation = nil %>
<%= error_messages_for :user %>
<% form_for :user, :url => users_path do |f| -%>
<p><label for=quot;loginquot;>Login</label><br/>
<%= f.text_field :login %></p>
<p><label for=quot;emailquot;>Email</label><br/>
<%= f.text_field :email %></p>
<p><label for=quot;passwordquot;>Password</label><br/>
<%= f.password_field :password %></p>
<p><label for=quot;password_confirmationquot;>Confirm Password</
label><br/>
<%= f.password_field :password_confirmation %></p>
<p><label for=quot;time_zonequot;>Time zone</label><br/>
<%= f.time_zone_select :time_zone, TimeZone.all %>
<p><%= submit_tag 'Sign up' %></p>
<% end -%>

16. Use before_filter to set time zone
in ApplicationController

17. class ApplicationController < ActionController::Base
helper :all
protect_from_forgery
include AuthenticatedSystem
before_filter :set_user_time_zone
private
def set_user_time_zone
Time.zone = current_user.time_zone if logged_in?
end
end

18. New!
Dirty tracking

19. $ ./script/console
Loading development environment (Rails 2.1.0)
>> Beer.find :first
=> #<Beer id: 1, name: quot;Coopers Sparkling Alequot;, created_at: quot;2008-06-05 11:31:55quot;,
updated_at: quot;2008-06-05 11:31:55quot;>
>> b.changed?
=> false
>> b.name = quot;Coopers Pale Alequot;
=> quot;Coopers Pale Alequot;
>> b.changed?
=> true
>> b.changed
=> [quot;namequot;]
>> b.name_changed?
=> true
>> b.name_was
=> quot;Coopers Sparkling Alequot;
>> b.changes
=> {quot;namequot;=>[quot;Coopers Sparkling Alequot;, quot;Coopers Pale Alequot;]}
>> b.save
=> true
>> b.changed?
=> false

20. Partial updates by default in new Rails 2.1 apps

21. SQL (0.000138) BEGIN
Beer Update (0.000304) UPDATE `beers` SET `updated_at` =
'2008-06-05 11:38:01', `name` = 'Coopers Pale Ale' WHERE
`id` = 1
SQL (0.005019) COMMIT

22. Warning!
Updates via other than attr= writer

23. >> b.name_will_change!
=> quot;Coopers Pale Alequot;
>> b.name.upcase!
=> quot;COOPERS PALE ALEquot;
>> b.name_change
=> [quot;Coopers Pale Alequot;, quot;COOPERS PALE ALEquot;]

24. New!
Gem Dependencies

25. $ rake -T gem
(in /Users/keithpitty/work/rails2.1demo)
rake gems # List the gems that this rails application ...
rake gems:build # Build any native extensions for unpacked gems
rake gems:install # Installs all required gems for this applic...
rake gems:unpack # Unpacks the specified gem into vendor/gems.
rake gems:unpack:dependencies # Unpacks the specified gems and its depende...
rake rails:freeze:gems # Lock this application to the current gems ...

26. # environment.rb
# Bootstrap the Rails environment, frameworks, and default configuration
require File.join(File.dirname(__FILE__), 'boot')
Rails::Initializer.run do |config|
config.time_zone = 'Sydney'
config.action_controller.session = {
:session_key => '_rails2.1demo_session',
:secret =>
'f4a5c1596f8fff01033b7417629c47fb6344748864b8f3a25fc6884b1ea41d214642f8eba01aa274ef9d128
1fc6cdc23bc33ea57ac66878a7b1164b96d875343'
}
config.gem quot;hpricotquot;, :version => '0.6', :source => quot;http://code.whytheluckystiff.netquot;
config.gem quot;aws-s3quot;, :lib => quot;aws/s3quot;
end

27. $ rake gems
(in /Users/keithpitty/work/rails2.1demo)
[I] hpricot = 0.6
[ ] aws-s3
I = Installed
F = Frozen

28. $ rake gems:install

29. $ rake gems:unpack

30. $ rake gems:unpack GEM=hpricot

31. $ rake gems:unpack:dependencies

32. $ rake gems:build

33. # test.rb
config.gem quot;mochaquot;

34. $ rake gems RAILS_ENV='test'
(in /Users/keithpitty/work/rails2.1demo)
[I] hpricot = 0.6
[ ] aws-s3
[ ] mocha
I = Installed
F = Frozen

35. New!
Named scope
courtesy of Nick Kallen

36. class Beer < ActiveRecord::Base
named_scope :available, :conditions => {:available => true}
named_scope :unavailable, :conditions => {:available => false}
named_scope :heavy, :conditions => {:full_strength => true}
named_scope :light, :conditions => {:full_strength => false}
named_scope :cats_piss, :conditions => {:rating => 0..3}
named_scope :drinkable, :conditions => ['rating > 3']
named_scope :minimum_rating,
lambda { |min_rating| { :conditions =>
['rating >= ?', min_rating] } }
named_scope :rated,
lambda { |rating| { :conditions =>
['rating = ?', rating] } }
named_scope :awesome,
lambda { |*args| { :conditions =>
['rating >= ?', (args.first || 9)] } }
end

37. >> Beer.count
=> 15
>> Beer.available.count
=> 9
>> Beer.heavy.available.count
=> 8
>> Beer.heavy.available.drinkable.count
=> 6
>> Beer.heavy.available.minimum_rating(7).count
=> 5
>> Beer.heavy.available.awesome.count
=> 3
>> Beer.heavy.available.awesome(10).count
=> 1

38. >> Beer.heavy.available.awesome(10)
=> [#<Beer id: 888319404, name: quot;Coopers Sparkling Alequot;,
brewer: quot;Coopersquot;, rating: 10, available: true,
full_strength: true, created_at: quot;2008-06-08 07:13:17quot;,
updated_at: quot;2008-06-08 07:13:17quot;>]

39. >> Beer.rated(0)
=> [#<Beer id: 177722761, name: quot;Fosters Lagerquot;,
brewer: quot;Fostersquot;, rating: 0, available: false,
full_strength: true, created_at: quot;2008-06-08
07:13:17quot;, updated_at: quot;2008-06-08 07:13:17quot;>]

40. Also: named scope extensions, anonymous scopes

41. New!
UTC-based migrations

43. Migration prefix no longer simply sequential

44. Migration prefix now uses UTC timestamp

45. mysql> select * from schema_migrations;
+----------------+
| version |
+----------------+
| 20080604194357 |
| 20080604195453 |
| 20080605112923 |
+----------------+
3 rows in set (0.00 sec)

46. Especially helpful for teams (avoids most conflicts)

47. Also helpful when working on branches

48. Migrations are applied intelligently

49. Also: change_table method introduced to migrations

50. New!
Better caching

51. Specify preferred caching engine in environment.rb

52. # Following options supplied in Rails 2.1:
ActionController::Base.cache_store = memory_store
ActionController::Base.cache_store = file_store, quot;path/to/cache/directoryquot;
ActionController::Base.cache_store = drb_store, quot;druby://localhost:9192quot;
ActionController::Base.cache_store = mem_cache_store, quot;localhostquot;

53. Or subclass ActiveSupport::Cache::Store
and implement read, write, delete and delete_matched methods

54. New!
A few other tidbits

55. rake rails:freeze:edge RELEASE=1.2.0

56. script/plugin install
supports
-e for svn export
and plugins hosted in Git repositories

57. script/dbconsole

58. >> quot; A string full of white spaces quot;.squish
=> quot;A string full of white spacesquot;

59. Resources
• http://weblog.rubyonrails.com/2008/6/1/rails-2-1-time-zones-
dirty-caching-gem-dependencies-caching-etc
• Ryan Bates’ Railscasts
• Ryan Daigle’s feature introductions
• Ruby on Rails 2.1: What’s New? by Carlos Brando

60. Thanks for listening
http://keithpitty.com