Rails 2 Upgrade Notes

Over the weekend I decided to try out Rails 2 by upgrading an existing site (http://www.trawlr.com/) from Rails 1.2.6 to Rails 2 RC2.

Check for deprecations before you upgrade

You may want to check your existing application for deprecated code before upgrading using the following rake task.

lib/tasks/rails.rake

desc "Checks your app and gently warns you if you are using deprecated code."
task :deprecated => :environment do
  deprecated = {
    '@params'    => 'Use params[] instead',
    '@session'   => 'Use session[] instead',
    '@flash'     => 'Use flash[] instead',
    '@request'   => 'Use request[] instead',
    '@env' => 'Use env[] instead',
    'find_all'   => 'Use find(:all) instead',
    'find_first' => 'Use find(:first) instead',
    'render_partial' => 'Use render :partial instead',
    'component'  => 'Use of components are frowned upon',
    'paginate'   => 'The default paginator is slow. Writing your own may be faster',
    'start_form_tag'   => 'Use form_for instead',
    'end_form_tag'   => 'Use form_for instead',
    ':post => true'   => 'Use :method => :post instead'
  }

  deprecated.each do |key, warning|
    puts '--> ' + key
    output = `cd '#{File.expand_path('app', RAILS_ROOT)}' && grep -n --exclude=*.svn* -r '#{key}' *`
    unless output =~ /^$/
      puts "  !! " + warning + " !!"
      puts '  ' + '.' * (warning.length + 6)
      puts output
    else
      puts "  Clean! Cheers for you!"
    end
    puts
  end
end

Use rake to execute the task.

rake deprecated

With any luck you won’t get many warnings; it should give you a rough estimate on how long your upgrade may take.

Getting Rails 2

First you need to get the RC2 (or newer) tagged Rails source using rake. This downloads the Rails framework to your appliction’s vender/rails directory.

rake rails:freeze:edge TAG=rel_2-0-0_RC2

Upgrade issues

After upgrading, it’s worth running your test suite looking for any problems. The following are issues I ran into to get trawlr.com working.

Singular resources now map to plural controllers – Override by using the :controller option in routes.rb

config/routes.rb

# Singleton reader resource
map.resource :reader, :controller => 'reader'

with_scope is now protected – Use .send(:with_scope) to call method

This caused an issue due to using the magic join model pattern, although the fix is relatively simple.

MyModel.send(:with_scope, args)

asset_packager plugin broken – Apply fix

The fabulous asset_packager plugin required a quick change to get working again (single-line change).

Index: vendor/plugins/asset_packager/lib/synthesis/asset_package_helper.rb
===================================================================
--- vendor/plugins/asset_packager/lib/synthesis/asset_package_helper.rb    (revision 86)
+++ vendor/plugins/asset_packager/lib/synthesis/asset_package_helper.rb    (working copy)
@@ -37,7 +37,7 @@
     private
       # rewrite compute_public_path to allow us to not include the query string timestamp
       # used by ActionView::Helpers::AssetTagHelper
-      def compute_public_path(source, dir, ext, add_asset_id=true)
+      def compute_public_path(source, dir, ext = nil, add_asset_id=true)
         source = source.dup
         source << ".#{ext}" if File.extname(source).blank?
         unless source =~ %r{^[-a-z]+://}

I still prefer this to the new Rails 2 asset merging as it also minifies JS and CSS files (including stripping comments) and also allows you to specify multiple asset groups (for example one grouping for the main site, another for an iPhone version). A word of caution if you use asset_packager you cannot take advantage of the new Rails 2 asset servers (see below).

# DOES NOT work with asset_packager
config.action_controller.asset_host = "http://asset%d.site.com"

Nested route helpers changed – Must specifiy parent resource

If you have any nested routes it’s likely you will have to alter the named route helpers, for example child_path is now parent_child_path.

start_form_tag and end_form_tag have been deprecated – Quick fix is to replace with form_tag and </form> respectively.

<%= form_tag articles_path %>
  <%= text_field :article, :title %>
  <%= submit_tag "Save" %>
</form>

render_without_layout has been deprecated – Use :layout => false instead.

render :layout => false

restful_authentication plugin is broken – Replace redirect_to_url (deprecated) in lib/authenticated_system.rb with to redirect_to.

Index: authenticated_system.rb
===================================================================
--- authenticated_system.rb    (revision 86)
+++ authenticated_system.rb    (working copy)
@@ -94,7 +94,7 @@
     # Redirect to the URI stored by the most recent store_location call or
     # to the passed default.
     def redirect_back_or_default(default)
-      session[:return_to] ? redirect_to_url(session[:return_to]) : redirect_to(default)
+      session[:return_to] ? redirect_to(session[:return_to]) : redirect_to(default)
       session[:return_to] = nil
     end

Optionally, rename your views

Rails 2 includes some changes to the way views are named. Previously you may have had show.rhtml and show.rjs which now become show.html.erb and show.js.rjs to indicate the mime type and template engines used. You don’t have to change your old views, but the following rake task should make it a quick change if you decide to. For trawlr.com I chose to use the new format for any new view templates but left the existing ones as they were (I’ll probably rename as changes are made on an individual basis).

lib/tasks/rails.rake

namespace 'views' do
  desc 'Renames all .rhtml views to .html.erb, .rjs to .js.rjs, .rxml to .xml.builder, and .haml to .html.haml'
  task 'rename' do
    Dir.glob('app/views/**/[^_]*.rhtml').each do |file|
      puts `svn mv #{file} #{file.gsub(/\.rhtml$/, '.html.erb')}`
    end

    Dir.glob('app/views/**/[^_]*.rxml').each do |file|
      puts `svn mv #{file} #{file.gsub(/\.rxml$/, '.xml.builder')}`
    end

    Dir.glob('app/views/**/[^_]*.rjs').each do |file|
      puts `svn mv #{file} #{file.gsub(/\.rjs$/, '.js.rjs')}`
    end
    Dir.glob('app/views/**/[^_]*.haml').each do |file|
      puts `svn mv #{file} #{file.gsub(/\.haml$/, '.html.haml')}`
    end
  end
end

Resources

For more information on Rails 2 refer to the preview release blog post. For $9 you can pick up a copy of Ryan Daigle’s worthwhile Rails 2 PDF book available via peepcode.