Porting an existing rails 2 site to rails 3

I have created a few rails 3 sites, but i have never before ported an existing rails2 application to rails3. I will describe the problems i encountered. First off there were some very good resources (step-by-step descriptions) to guide me through it: The conversion ran pretty smoothly, but I will describe the things i bumped into that were less obvious.

ActiveSupport::Callbacks

Before we wrote: [ruby] module Workflow class Base define_callbacks :before_something, :after_something def some_method run_callbacks :before_something puts "some method" run_callbacks :after_something end end class SpecificWorkflow < Base before_something :do_something def do_something puts "something" end end [/ruby] Now, this has changed. Into the following: [ruby] module Workflow class Base define_callbacks :something def some_method run_callbacks :something do puts "some method" end end end class SpecificWorkflow < Base set_callback :something, :before, :do_something def do_something puts "something" end end [/ruby] Which is pretty nice. It has the disadvantage we can only use :before and :after callbacks anymore, but that was easily solved.

ActionController::ParamsParser

We hooked into the Rack middleware before the ActionController::ParamsParser to make sure we return Bad Request when the parsing fails. This middleware has been renamed to ActionDispatch::ParamsParser. Easy fix :)

safe_helper removed?

We prepared our Rails 2 project a long time ago, and used the rails_xss plugin. We used the safe_helper all over our helper-methods, but apparently this is not supported in Rails 3. Bummer. So, before [ruby] def some_helper "<strong>something</strong>" end safe_helper :some_helper [/ruby] After: [ruby] def some_helper "<strong>something</strong>".html_safe end [/ruby] A bit annoying to do, a bit unfortunate, because we thought we were preparing ourselves for a smoother upgrade. Not entirely so.

The routes!

Only after those steps did my rails get far enough to discover my routes. I did not change anything about the routes, just placed inside the correct block. I deleted my index.html and put back my original application.html.haml and the first view was working.

The missing to_key

The to_key was missing inside the user_session model. I described that solution already in this blogpost. So i just needed to fix that.

Replacing ActionController::RecordIdentifier.singular_class_name

We used ActionController::RecordIdentifier.singular_class_name, in rails3 this is replaced by ActionController::RecordIdentifier.dom_class.

Missing translations

A feature we used a lot was I18n.t('.filter') and this would look for operators.filter.filter because the line was inside a partial _shared/_filter.html.haml and called from the operators/index.html.haml. Now this does not work anymore, and now instead I18n looks for _shared.filter.filter. I did not find an easy way to solve this, just moved some translations. Luckily we did not override the translations of a partial based on the context where it was rendered yet. Does anybody has any tips on that?

Upgrading javascript helpers

In rails3 unobtrusive is the way to go. So, a remote_form_for like [ruby] - form_remote_tag :url => update_url do [/ruby] becomes [ruby] - form_tag :url => update_url, :remote => true do [/ruby] Which seems easy enough. It does get more complicated when the :update tag is used. For example: [ruby] - remote_form_for post, :update => {:success => "result_#{id}"} do |form| [/ruby] becomes [ruby] - remote_form_for post, :remote => true, :html => {:class => 'remote-post-form', :'data-update' => "#result_#{id}"} do |form| [/ruby] The :update is no longer supported as before, and we have to perform some glueing ourselves. So i replaced the :update by data-update. And then inside javascript (e.g. application.js) we can do the following: [javascript] jQuery(function($) { $(".remote-post-form") .bind("ajax:success", function(data, status, xhr) { var update_selector = $(this).attr('data-update'); $(update_selector).html(status); }); }); [/javascript] If you need more elaborate example, check this question on stackoverflow.

master_helper_module

This has been replaced by _helpers.

active_layout

The active_layout method, of a controller, no longer exists inside rails3. To replace it you need to use two methods:
  • action_has_layout? returns true if a layout exists.
  • To get the layout-name, i have no better solution then calling the private method _layout. This can be done, as known, by doing controller.send(:_layout).

Upgrade rspec

I had to upgrade Rspec 1 to v2. First off in the Gemfile i added the correct version. I removed the rspec.rake file. I ran [ruby] rails g rspec:install [/ruby] But still all rake spec commands were missing. The fix was simple. In the Gemfile make sure the rspec-rails is also usable from development mode: [ruby] group :development, :test do gem 'rspec-rails' end [/ruby] Now on to fixing the tests!

Fixing the tests

In the upgrade from rspec1 to rspec2 a lot of things have changed. What i encountered:
  • replace all Spec:: by RSpec::
  • controller_name 'users' no longer exists, write a surrounding describe UsersController do instead (that is also clearer imho)
  • ...

Extending Rspec::Rails::ExampleGroup::ControllerExampleGroup

Before, in rspec1, ControllerExampleGroup was a class and you could add code to it. So for instance, we had a file like this in our support folder: [ruby] module RSpec module Rails module Example class ControllerExampleGroup let(:the_account ) { Factory(:account) } let(:the_user ) { Factory(:user)} end end end end [/ruby] A bit larger, but you get the picture: this allowed us to define a set of shared let definitions. In rspec-2 this is no longer possible this way, because ControllerExampleGroup is now a module. I handled that like this: [ruby] module Lets def self.included(base) base.let(:the_account ) { Factory(:account) } base.let(:the_user ) { Factory(:user)} end end [/ruby] and inside my spec_helper this file is automatically required (since it is stored in the support folder) and i just add [ruby] config.include(Lets) [/ruby]

Rspec: replace config.extend

I also noticed that using config.extend(ModuleName) dit not work anymore. Instead i had to write (on the same place, inside the configure block) : [ruby] Rspec.configure do |config| .. include ModuleName .. end [/ruby] and that worked for me.

More?

Do you have more hints to share? What bumps did you find and how did you overcome them?
Comments
Jon Seidel 2011-04-05 21:45:00 UTC

I just tried a similar upgrade and have 2 problems, one of which I 'fixed' and one still outstanding. 1. Kept getting error "uninitialized constant Authlogic' which I fixed by adding a require 'authlogic' in application.rb. I am not convinced that this is correct, but it did get things to work after everything else I tried failed (including viewing your referenced posts). 2. I am now getting the following error immediately after entering an id/password and clicking the submit button from my login page. Seems to me it's a routes problem but I can't figure it out: Unknown action The action '#' could not be found for UserSessionsController Any comments/suggestions appreciated and maybe #1 will help someone else.

nathanvda 2011-04-06 06:30:55 UTC

Hi Jon, if you are using a non-standard gem-line in your Gemfile, it could help to add an explicit require there. E.g. something like <code>gem "authlogic-rails3", :git => '...', :require => 'authlogic'</code>. Not sure if that is the case. I did need to add more explicit requires, while i also needed to add the <code>lib</code> path to the load-path explicitly. Your second problem looks like a routing problem indeed :)

Jon Seidel 2011-04-06 20:01:00 UTC

I tried putting the 'require' in the Gemfile, but that didn't work... dunno why not. I was finally able to work around the uninitialized constant problem by just putting require 'authlogic' in my application.rb file, right under the require 'rails/all' expression.

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