url_locale

Add content-language to the response header using Rack. The locale variable is parsed from request URL, if no locale can be detected then I18n.default_locale will be your fallback.

Rack

Rack middleware parses the URL and sets the response header content-language attribute accordingly. Since the header is passed on to the web server, inserting <meta http-equiv="Content-Language" content="en"/> in the response body is superfluous. Please note that cached responses passing through Rack also will get the correct content-language header (can be tricky to configure the web server to do this).

Detect URL locale

The gem will parse request.url for I18n.available_locales in the following order:

  1. request.url listed in config/url_locale.yml?
  2. request.path starts with I18n.available_locales
  3. I18n.default_locale

Example

# config/url_locale.yml
en:
  - http://localehost:3000
  - http://example.com
sv:
  - http://localehost:3001
  - http://example.se

I18n.default_locale => :en
I18n.available_locales => [:en, :sv]

http://example.com                        => "en"
http://sv.example.com                     => "en" # fallback
http://example.se/about                   => "sv"
http://example.com/sv/om                  => "en"
http://www.example.com/sv/om              => "sv" # parse path

http://localhost:3000                     => "en"
http://sv.localhost:3000                  => "en" # fallback
http://localhost:3001/about               => "sv"
http://localhost:3000/sv/om               => "en"
http://localhost:3002/sv/om              => "sv" # parse path

If a locale can't be detected, fallback will be I18n.default_locale

Installation and configuration

  1. Run rake middleware RAILS_ENV=development and rake middleware RAILS_ENV=production
  2. Notice the order of the middleware for each environment
  3. Add gem 'url_locale' to Gemfile
  4. Insert UrlLocale::Middleware as the first middleware in the Rack middleware stack
  5. (optional) create config/url_locale.yml
  6. Add before filter in application to set locale

Rails 3.1 example

$ rake middleware RAILS_ENV=development
use ActionDispatch::Static
use Rack::Lock
use #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x101fefef0>
use Rack::Runtime
use Rack::MethodOverride
use Rails::Rack::Logger
use ActionDispatch::ShowExceptions
use ActionDispatch::RemoteIp
use Rack::Sendfile
use ActionDispatch::Reloader
use ActionDispatch::Callbacks
use ActiveRecord::ConnectionAdapters::ConnectionManagement
use ActiveRecord::QueryCache
use ActionDispatch::Cookies
use ActionDispatch::Session::CookieStore
use ActionDispatch::Flash
use ActionDispatch::ParamsParser
use ActionDispatch::Head
use Rack::ConditionalGet
use Rack::ETag
use ActionDispatch::BestStandardsSupport
run Learning::Application.routes

$ rake middleware RAILS_ENV=production
use Rack::Cache
use Rack::Lock
use #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x101feeb68>
use Rack::Runtime
use Rack::MethodOverride
use Rails::Rack::Logger
use ActionDispatch::ShowExceptions
use ActionDispatch::RemoteIp
use Rack::Sendfile
use ActionDispatch::Callbacks
use ActiveRecord::ConnectionAdapters::ConnectionManagement
use ActiveRecord::QueryCache
use ActionDispatch::Cookies
use ActionDispatch::Session::CookieStore
use ActionDispatch::Flash
use ActionDispatch::ParamsParser
use ActionDispatch::Head
use Rack::ConditionalGet
use Rack::ETag
use ActionDispatch::BestStandardsSupport
run Learning::Application.routes


# Gemfile
gem 'url_locale'

# config/environments/development.rb
config.middleware.insert_before "ActionDispatch::Static", UrlLocale::Middleware

# config/environments/production.rb
config.middleware.insert_before "Rack::Cache", UrlLocale::Middleware

# config/url_locale.yml (optional configuration file)
en:
  - http://localehost:3000
  - http://example.com
sv:
  - http://localehost:3001
  - http://example.se

# app/controllers/application_controller.rb
before_filter :set_locale

def set_locale
  I18n.locale = UrlLocale.detect request
end

Development

There is room for improvement for this gem

  • Easier installation
  • Other ideas?

If url_locale gets more then 1000 downloads, further development might be worth the effort :)

Copyright (c) 2011 Dan Byström. See LICENSE.txt for further details.