1. Migrating PriceChirp to Rails 3.0
Steven Evatt
Blog: http://www.evatt.com/blog
Web: http://PriceChirp.com
Twitter: @sevatt
Houston-RoR Nov 2010
The pain points

2. 2
Today We'll Cover:

Why Upgrade?

Pain points / Issues

Tips

Take Aways

3. 3
Full Disclosure

PriceChirp is my main side project designed to
help people (myself included) save money on
Amazon

My background is in Perl

4. 4
Why???

Gem ecosystem is starting to require Rails 3.0

Too many deprecation notices

5. 5
How much work was it?

3 weeks of nights / weekends

According to svn

Paths added 67

Paths modified 112

Paths removed 45

Replaced Restful_Authentication with Devise

Converted from Prototype to UJS jQuery

6. 6
Where to start?

Upgrade to Rails 2.3.9

Upgrade Gems

Fix code to remove deprecation message

Bundler

Have test for critical functionality

Install Rails_upgrade plugin

Make a new branch in your source control

7. 7
Source Control

Svn copy http://svn...com/pricechirp/trunk/
http://svn...com/pricechirp/branches/migrate_to_rails
3

Svn checkout
http://svn...com/pricechirp/branches/migrate_to_rails
3 migrate

8. 8
Plugin → Rails_upgrade

Documentation out of order and gives wrong
syntax for rails command

Mostly run from rails 2.3

Useful rake tasks

Rake rails:upgrade:check

Rake rails:upgrade:backup

Rake rails:upgrade:routes

Rake rails:upgrade:gems

Rake rails:upgrade:configuration

9. 9
Installing Rails 3

Rails new .

Creates a rails3 project
with the name of the
current directory

If directory name is
migrate:

Application name is
Migrate::Application

Must update in 12 places
to change

10. 10
Bundler

Bundler manages an application's dependencies
through its entire life across many machines
systematically and repeatably.

Gemfile

gem “rack”, “~>1.1”

gem “rspec, :requires => “spec”

It doesn’t take long before you want to use
bundler on all projects

11. 11
Bundler II

Passenger is not ignoring my Gemfile :test,
:development block in production

To get bundler to work with capistrano:

Add to deploy.rb:
require "bundler/capistrano"

12. 12
Upgrade Gems

gem ‘will_paginate’, ‘~> 3.0.pre2’, :require =>
‘will_paginate’

factory_girl_rails => compatibility mode

13. 13
Passenger

Apache configuration changed

from:
RailsEnv development

to:
RackEnv development

14. 14
Upgrade Plugins

Restful Authentication → Devise

copy crypted_password => encrypted_password

copy salt => encrypted_salt

set confirmed date

nil is a valid salt with Restful Auth, not in Devise

Change helper methods
− :login_required → :authenticate_user!
− logged_in? → user_signed_in?

Exception_notification

15. 15
RAILS_ENV and RAILS_ROOT
 RAILS_ENV → Rails.env
 Rails.env.production?
− If RAILS_ENV == “production”
− If Rails.env.production?
 RAILS_ROOT → Rails.root
 RAILS_CACHE → Rails.cache

16. 16
XSS protection is everywhere

Learn to love .html_safe.

All strings are not safe until flagged as safe.

17. 17
Views

forms helpers changed from <% to <%=

removed error_messages_for

link_to_remote

Use :remote => true

link_to

18. 18
UJS / jQuery

Converted rjs to erb

Converted from Prototype to jQuery

Get jQuery
− http://docs.jquery.com/Downloading_jQuery
− /public/javascripts/jquery-1.4.2.min.js

Copy rails.js from
github.com/rails/jquery-ujs/raw/master/src/rails.js

:remote => true

19. 19
Active Record Changes

passing options hash containing :conditions,
:include, :joins, :limit, :offset, :order,
:select, :readonly, :group, :having, :from,
:lock to any of the ActiveRecord provided
class methods, is now deprecated.

Find → where

find_by_x('xxx') => where(:x => ‘xxx’).first

where(‘b like ?’, value)

20. 20
Active Record “Bug”

select('distinct(x)') is ignored when passed to
.count
Example
Item.where('updated_at < ?',
1.days.ago ).select('distinct(asin)').all
Produces the following query:
Item Load (6.3ms) SELECT distinct(asin) FROM `items`
WHERE (updated_at < '2010-10-16 01:06:05')

21. 21
Active Record “Bug” II
Now, when we use .count instead of .all, the .select call
is ignored:
Item.where('updated_at < ?',
1.days.ago ).select('distinct(asin)').count
Yields:
SQL (5.4ms) SELECT COUNT(*) AS count_id FROM
(SELECT 1 FROM `items` WHERE (updated_at <
'2010-10-16 01:09:55')) AS subquery

22. 22
Active Record “Bug” III

Work around
Put a .all before the .count
Item.where('updated_at < ?',
1.days.ago ).select('distinct(asin)').all.count
Issue
If you attempt to use :group ie .count(:group => :asin) you
get an error

More Info on “bug”

https://rails.lighthouseapp.com/projects/8994/
tickets/5698-select-ignored-in-subquery-
when-querying-with-count

23. 23
Custom to_s formatting for dates
Example: Time.now.to_s(:js)

From:
ActiveSupport::CoreExtensions::Time::Conversions::DATE_FOR
MATS.merge!(:js => ‘%m %d, %Y %H:%M:%S’)

To:
Time::DATE_FORMATS[:js] = ‘%m %d, %Y %H:%M:%S’

24. 24
Logging Rails.cache Activity

By default, Rails3 does not log Rails.cache activity
Cache read: user.default
Cache fetch_hit: user.default
Cache read: user.count ({:expires_in=>300 seconds})
Cache generate: user.count ({:expires_in=>300 seconds})
Cache write: user.count ({:expires_in=>300 seconds})

To enable logging
In environment.rb
Rails.cache.logger ||= Rails.logger

25. 25
Action Mailer

Action_mailer defaults to :smtp although
everything says it defaults to :sendmail
config.action_mailer.delivery_method = :sendmail

Action_mailer requires
default_url_options[:host] to be defined
config.action_mailer.default_url_options[:host] = {
:host => ‘pricechirp.com’ }

26. 26
script/* replaced by script/rails

script/rails replaces all the scripts that used to
be in the script directory
Safe to remove: about, console, dbconsole, destroy
generate, plugin, runner, and server

27. 27
RSS

Had to wrap my
“xml.description” output
in a CDATA block for it
to display
<![CDATA[
…
]]>

28. 28
Validate-on-callback methods

validate_on_create
validate :x, :on => :create

29. 29
Remove Debugging Statements

logger.info request.inspect
Rails 2.3.9 Rails 3.0
request.inspect 5.9k 330k

30. 30
Mime::Type
Error:
A ActionView::MissingTemplate occurred in pages#index:
Missing template pages/index with {:locale=>[:en, :en],
:handlers=>[:builder, :erb, :rjs, :rhtml, :rxml], :formats=>[:"text/*"]} in
view paths ….
actionpack (3.0.1) lib/action_view/paths.rb:15:in `find'
Solution:
In /config/initializers/mime_types.rb, add:
Mime::Type.register “text/*”, :html

31. 31
Current Issues I
A ActionController::UnknownHttpMethod occurred in #:
PROPFIND, accepted HTTP methods are get, head, put,
post, delete, and options actionpack (3.0.1)
lib/action_dispatch/http/request.rb:59:in `request_method'

32. 32
Current Issues II
Bundler – During a “cap deploy”
...
[pricechirp.com] executing command
** [out :: pricechirp.com] (in /home/pricechirp)
** [out :: pricechirp.com] Could not find gem 'rspec-rails (>= 2.0.1, runtime)' in any of
the gem sources.
** [out :: pricechirp.com] Try running `bundle install`.
command finished
*** [deploy:update_code] rolling back
...

33. 33
Take Aways

Upgrade / fix deprecated code as
best you can before you start

Use Rails_upgrade plugin

XSS Protection is everywhere

Syntax changes:

Views form helpers

Link_to_remote replaced with :remote => true

Active Record changes: .find → .where

Validate-on-callback

Configurations

There is a lot of deprecated
advice out there, remember
to check the dates

34. 34
Thanks for Coming!
Steven Evatt
Email: steven@evatt.com
Site: http://PriceChirp.com
Blog: http://www.evatt.com/blog
Twitter: @sevatt