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Rails 3.1: Upgrading a Simple App — Part 1

By Steph Skardal
September 21, 2011

Here at End Point, I’ve worked with a few Rails 3 applications in production and a couple of Rails 3.1 apps in development, so I’ve become familiar with the new features and functionality including the Rails 3.1 Asset Pipeline that I mentioned earlier this year. I thought it was a good time to upgrade our website to Rails 3.1 and share the experience.

To start, here’s a quick summary of our website:

  • Simple Rails application running on Rails 2.1.2 with no database
  • Static pages throughout the site, fully cached
  • Rake tasks to generate partials throughout the site to display dynamic blog content
  • Site uses a moderate amount of jQuery and jQuery plugins.
  • Site is optimized in terms of asset serving (ETags, Expires headers, CSS sprites, etc.)

While I’ve worked with a few Rails 3 apps, I haven’t been involved in the actual upgrade process myself. There are plenty of resources out there with upgrade advice, including a few RailsCasts (one, two, and three). My favorite resource was the rails_upgrade gem, a gem that is now officially supported by Rails to help with the upgrade process. I followed the instructions to install the gem (script/plugin install git://github.com/rails/rails_upgrade.git) to install it as a plugin in our site’s application in a fresh git branch (on a camp, of course!).

The rails_upgrade provides a few new rake tasks for checking compatibility, upgrading the routes, creating a Gemfile, and upgrading configuration. For me, the most valuable task was the rake rails:upgrade:check task. Here’s what the output looked like for this app:

<b>Deprecated session secret setting</b>
Previously, session secret was set directly on ActionController::Base; it's now config.secret_token.
More information: http://lindsaar.net/2010/4/7/rails_3_session_secret_and_session_store

The culprits:
 - config/initializers/session_store.rb

<b>Old router API</b>
The router API has totally changed.
More information: http://yehudakatz.com/2009/12/26/the-rails-3-router-rack-it-up/

The culprits:
 - config/routes.rb

<b>New file needed: config/application.rb</b>
You need to add a config/application.rb.
More information: http://omgbloglol.com/post/353978923/the-path-to-rails-3-approaching-the-upgrade

The culprits:
 - config/application.rb

<b>Deprecated constant(s)</b>
Constants like RAILS_ENV, RAILS_ROOT, and RAILS_DEFAULT_LOGGER are now deprecated.
More information: http://litanyagainstfear.com/blog/2010/02/03/the-rails-module/

The culprits:
 - app/views/layouts/application.rhtml
 - ...

<b>Soon-to-be-deprecated ActiveRecord calls</b>
Methods such as find(:all), find(:first), finds with conditions, and the :joins option will soon be deprecated.
More information: http://m.onkey.org/2010/1/22/active-record-query-interface

The culprits:
 - app/views/blog_archive/_ruby_on_rails.html.erb
        - ...

<b>Deprecated AJAX helper calls</b>
AJAX javascript helpers have been switched to be unobtrusive and use :remote => true instead of having a seperate function to handle remote requests.
More information: http://www.themodestrubyist.com/2010/02/24/rails-3-ujs-and-csrf-meta-tags/

The culprits:
 - app/views/blog_archive/_company.html.erb
        - ...

<b>Deprecated ActionMailer API</b>
You're using the old ActionMailer API to send e-mails in a controller, model, or observer.
More information: http://lindsaar.net/2010/1/26/new-actionmailer-api-in-rails-3

The culprits:
 - app/controllers/contact_controller.rb

<b>Old ActionMailer class API</b>
You're using the old API in a mailer class.
More information: http://lindsaar.net/2010/1/26/new-actionmailer-api-in-rails-3

The culprits:
 - app/models/contact_form.rb

As you can see, the upgrade check spits out a list of necessary and recommended upgrades and the corresponding culprits. It’s also nice that the task provides documentation in the form of a link for each message. Studying the source of the plugin, I found additional examples of upgrade messages: named_scope updates, validate_on_* syntax, test_help path updates, gem bundling configuration, Rails generator API syntax updates, messaging on known broken plugins (e.g. searchlogic, cucumber, nifty-generators), and depracation on ERb helper and AJAX calls.

I went through and applied my updates, according to the checklist. Notable updates were:

Routing updates


ActionController::Routing::Routes.draw do |map|
  map.root :controller => 'home', :action => 'index'
  map.connect 'contact/submit', :controller => 'contact', :action => 'submit'
  map.connect ':controller/:id'
  map.connect '*path', :controller => 'redirect'


Endpoint::Application.routes.draw do
  root :to => 'home#index'
  match 'contact/submit' => 'contact#submit'
  match ':controller(/:id)', :action => :index
  match '*path' => 'redirect#index'

Introduction of a Gemfile

source 'http://rubygems.org'

gem 'rails', '3.1.0'
gem 'json'

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails', "  ~> 3.1.0"
  gem 'coffee-rails', "~> 3.1.0"
  gem 'uglifier'

gem 'jquery-rails'
gem 'fastercsv'
gem 'execjs'
gem 'therubyracer'
gem 'rake', '0.8.7'

Renaming rhtml files

Something that didn’t come up in the rails upgrade check that is required to have a working app is renaming all rhtml files to html.erb, briefly described here.

Basic Asset Management

To get the basic app working, I moved the public/stylesheets and public/javascripts to the new app/assets directories to start. I did not move the images out of the public/ directory because several of the images in the application are referenced by blog articles.

Database-less Application

I followed the directions here combined with a bit of troubleshooting to configure a Rails 3.1 app that does not require a database.


The upgrade was a relatively painless process, although it still took a few hours for even the most basic application with only a handful of controllers, routes, and one mailer. My experience suggests that with a more complex application, the upgrade will take at least a few hours, if not much more. This simple app doesn’t do much with remote forms and links, so I didn’t spend any time upgrading the app to work with the jquery-ujs gem. Also, I obviously didn’t mess around with Rails 3.1 ActiveRecord issues since the application is database-less. Both of these items may add significant overhead to the upgrade process.

I spent a significant amount of time working with the new asset pipeline and restructuring the assets, which I plan to describe in Part 2 of the upgrade. Stay tuned!

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