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

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Today We'll Cover:

Why Upgrade? Pain points / Issues Tips Take Aways

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Full Disclosure

PriceChirp is my main side project designed to help people (myself included) save money on Amazon

My background is in Perl

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Why???

Gem ecosystem is starting to require Rails 3.0 Too many deprecation notices

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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

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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

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Source Control

Svn copy http://svn...com/pricechirp/trunk/ http://svn...com/pricechirp/branches/migrate_to_rails3

Svn checkout http://svn...com/pricechirp/branches/migrate_to_rails3 migrate

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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

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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

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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

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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"

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Upgrade Gems

gem ‘will_paginate’, ‘~> 3.0.pre2’, :require => ‘will_paginate’

factory_girl_rails => compatibility mode

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Passenger

Apache configuration changed from:

RailsEnv development to:

RackEnv development

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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

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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

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XSS protection is everywhere

Learn to love .html_safe. All strings are not safe until flagged as safe.

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Views

forms helpers changed from <% to <%= removed error_messages_for link_to_remote

Use :remote => true link_to

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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

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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)

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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')

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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

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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

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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’

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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

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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’ }

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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

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RSS

Had to wrap my “xml.description” output in a CDATA block for it to display

<![CDATA[

…

]]>

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Validate-on-callback methods

validate_on_create

validate :x, :on => :create

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Remove Debugging Statements

logger.info request.inspect

Rails 2.3.9 Rails 3.0

request.inspect 5.9k 330k

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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

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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'

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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...

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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

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Thanks for Coming!

Steven Evatt

Email: steven@evatt.com

Site: http://PriceChirp.com

Blog: http://www.evatt.com/blog

Twitter: @sevatt