route_translator

RouteTranslator

RouteTranslator is a gem to allow you to manage the translations of your app routes with a simple dictionary format.

It started as a fork of the awesome translate_routes plugin by Raúl Murciano.

Right now it works with Rails 6.1, 7.x, and 8.0

Quick Start

• If you have this routes.rb file originally:

  Rails.application.routes.draw do
    namespace :admin do
      resources :cars
    end
  
    resources :cars
  end
  

  The output of bundle exec rails routes would be:

      admin_cars GET    /admin/cars(.:format)          admin/cars#index
                 POST   /admin/cars(.:format)          admin/cars#create
   new_admin_car GET    /admin/cars/new(.:format)      admin/cars#new
  edit_admin_car GET    /admin/cars/:id/edit(.:format) admin/cars#edit
       admin_car GET    /admin/cars/:id(.:format)      admin/cars#show
                 PUT    /admin/cars/:id(.:format)      admin/cars#update
                 DELETE /admin/cars/:id(.:format)      admin/cars#destroy
            cars GET    /cars(.:format)                cars#index
                 POST   /cars(.:format)                cars#create
         new_car GET    /cars/new(.:format)            cars#new
        edit_car GET    /cars/:id/edit(.:format)       cars#edit
             car GET    /cars/:id(.:format)            cars#show
                 PUT    /cars/:id(.:format)            cars#update
                 DELETE /cars/:id(.:format)            cars#destroy
  

• Add the gem to your Gemfile:

  gem 'route_translator'
  

  And execute bundle install

• Generate the default initializer:

  bundle exec rails g route_translator:install
  

• Wrap the groups of routes that you want to translate inside a localized block:

  Rails.application.routes.draw do
    namespace :admin do
      resources :cars
    end
  
    localized do
      resources :cars
  
      get 'pricing', to: 'home#pricing', as: :pricing
    end
  end
  

  And add the translations to your locale files, for example:

  es:
    routes:
      cars: coches
      new: nuevo
      pricing: precios
  fr:
    routes:
      cars: voitures
      new: nouveau
      pricing: prix
  

• Your routes are translated! Here's the output of your bundle exec rails routes now:

          Prefix Verb   URI Pattern                     Controller#Action
      admin_cars GET    /admin/cars(.:format)           admin/cars#index
                 POST   /admin/cars(.:format)           admin/cars#create
   new_admin_car GET    /admin/cars/new(.:format)       admin/cars#new
  edit_admin_car GET    /admin/cars/:id/edit(.:format)  admin/cars#edit
       admin_car GET    /admin/cars/:id(.:format)       admin/cars#show
                 PATCH  /admin/cars/:id(.:format)       admin/cars#update
                 PUT    /admin/cars/:id(.:format)       admin/cars#update
                 DELETE /admin/cars/:id(.:format)       admin/cars#destroy
         cars_fr GET    /fr/voitures(.:format)          cars#index {:locale=>"fr"}
         cars_es GET    /es/coches(.:format)            cars#index {:locale=>"es"}
         cars_en GET    /cars(.:format)                 cars#index {:locale=>"en"}
                 POST   /fr/voitures(.:format)          cars#create {:locale=>"fr"}
                 POST   /es/coches(.:format)            cars#create {:locale=>"es"}
                 POST   /cars(.:format)                 cars#create {:locale=>"en"}
      new_car_fr GET    /fr/voitures/nouveau(.:format)  cars#new {:locale=>"fr"}
      new_car_es GET    /es/coches/nuevo(.:format)      cars#new {:locale=>"es"}
      new_car_en GET    /cars/new(.:format)             cars#new {:locale=>"en"}
     edit_car_fr GET    /fr/voitures/:id/edit(.:format) cars#edit {:locale=>"fr"}
     edit_car_es GET    /es/coches/:id/edit(.:format)   cars#edit {:locale=>"es"}
     edit_car_en GET    /cars/:id/edit(.:format)        cars#edit {:locale=>"en"}
          car_fr GET    /fr/voitures/:id(.:format)      cars#show {:locale=>"fr"}
          car_es GET    /es/coches/:id(.:format)        cars#show {:locale=>"es"}
          car_en GET    /cars/:id(.:format)             cars#show {:locale=>"en"}
                 PATCH  /fr/voitures/:id(.:format)      cars#update {:locale=>"fr"}
                 PATCH  /es/coches/:id(.:format)        cars#update {:locale=>"es"}
                 PATCH  /cars/:id(.:format)             cars#update {:locale=>"en"}
                 PUT    /fr/voitures/:id(.:format)      cars#update {:locale=>"fr"}
                 PUT    /es/coches/:id(.:format)        cars#update {:locale=>"es"}
                 PUT    /cars/:id(.:format)             cars#update {:locale=>"en"}
                 DELETE /fr/voitures/:id(.:format)      cars#destroy {:locale=>"fr"}
                 DELETE /es/coches/:id(.:format)        cars#destroy {:locale=>"es"}
                 DELETE /cars/:id(.:format)             cars#destroy {:locale=>"en"}
      pricing_fr GET    /fr/prix(.:format)              home#pricing {:locale=>"fr"}
      pricing_es GET    /es/precios(.:format)           home#pricing {:locale=>"es"}
      pricing_en GET    /pricing(.:format)              home#pricing {:locale=>"en"}
  

  Note that only the routes inside a localized block are translated.

  In :development environment, I18n is configured by default to not use fallback language. When a translation is missing, it uses the translation key last segment as fallback (cars and new in this example).

  In :production environment, you should either set config.i18n.fallbacks = false or set up translations for your routes in every languages.

• If you want to set I18n.locale from the url parameter locale, add the following line in your ApplicationController or in the controllers that have translated content:

  around_action :set_locale_from_url
  

  Note: you might be tempted to use before_action instead of around_action: just don't. That could lead to thread-related issues.

Changing the Language

To change the language and reload the appropriate route while staying on the same page, use the following code snippet:

link_to url_for(locale: 'es'), hreflang: 'es', rel: 'alternate'

Although locales are stored by Rails as a symbol (:es), when linking to a page in a different locale you need to use a string ('es'). Otherwise, instead of a namespaced route (/es/my-route) you will get a parameterized route (/my-route?locale=es).

If the page contains a localized slug, the above snippet does not work and a custom implementation is needed.

More information at Generating translated URLs

Namespaces

You can translate a namespace route by either its name or path option:

• Wrap the namespaces that you want to translate inside a localized block:

  Rails.application.routes.draw do
    localized do
      namespace :admin do
        resources :cars, only: :index
      end
  
      namespace :sold_cars, path: :sold do
        resources :cars, only: :index
      end
    end
  end
  

  And add the translations to your locale files, for example:

  es:
    routes:
      admin: administrador
      cars: coches
      new: nuevo
      pricing: precios
      sold: vendidos
  fr:
    routes:
      admin: administrateur
      cars: voitures
      new: nouveau
      pricing: prix
      sold: vendues
  

• Your namespaces are translated! Here's the output of your bundle exec rails routes now:

             Prefix Verb URI Pattern                           Controller#Action
      admin_cars_fr GET  /fr/administrateur/voitures(.:format) admin/cars#index {:locale=>"fr"}
      admin_cars_es GET  /es/administrador/coches(.:format)    admin/cars#index {:locale=>"es"}
      admin_cars_en GET  /admin/cars(.:format)                 admin/cars#index {:locale=>"en"}
  sold_cars_cars_fr GET  /fr/vendues/voitures(.:format)        sold_cars/cars#index {:locale=>"fr"}
  sold_cars_cars_es GET  /es/vendidos/coches(.:format)         sold_cars/cars#index {:locale=>"es"}
  sold_cars_cars_en GET  /sold/cars(.:format)                  sold_cars/cars#index {:locale=>"en"}
  

Inflections

At the moment inflections are not supported, but you can use the following workaround:

localized do
  resources :categories, path_names: { new: 'new_category' }
end

en:
  routes:
    category: category
    new_category: new

es:
  routes:
    category: categoria
    new_category: nueva

          Prefix Verb   URI Pattern                       Controller#Action
   categories_es GET    /es/categorias(.:format)          categories#index {:locale=>"es"}
   categories_en GET    /categories(.:format)             categories#index {:locale=>"en"}
                 POST   /es/categorias(.:format)          categories#create {:locale=>"es"}
                 POST   /categories(.:format)             categories#create {:locale=>"en"}
 new_category_es GET    /es/categorias/nueva(.:format)    categories#new {:locale=>"es"}
 new_category_en GET    /categories/new(.:format)         categories#new {:locale=>"en"}
edit_category_es GET    /es/categorias/:id/edit(.:format) categories#edit {:locale=>"es"}
edit_category_en GET    /categories/:id/edit(.:format)    categories#edit {:locale=>"en"}
     category_es GET    /es/categorias/:id(.:format)      categories#show {:locale=>"es"}
     category_en GET    /categories/:id(.:format)         categories#show {:locale=>"en"}
                 PATCH  /es/categorias/:id(.:format)      categories#update {:locale=>"es"}
                 PATCH  /categories/:id(.:format)         categories#update {:locale=>"en"}
                 PUT    /es/categorias/:id(.:format)      categories#update {:locale=>"es"}
                 PUT    /categories/:id(.:format)         categories#update {:locale=>"en"}
                 DELETE /es/categorias/:id(.:format)      categories#destroy {:locale=>"es"}
                 DELETE /categories/:id(.:format)         categories#destroy {:locale=>"en"}

Configuration

You can configure RouteTranslator via an initializer or using the different environment config files.

RouteTranslator.config do |config|
  config.force_locale = true
  config.locale_param_key = :my_locale
end

Available Configurations

Option	Description	Default
available_locales	Limit the locales for which URLs should be generated for. Accepts an array of strings or symbols. When empty, translations will be generated for all I18n.available_locales	[]
disable_fallback	Create routes only for locales that have translations. For example, if we have /examples and a translation is not provided for es, the route helper of examples_es will not be created. Useful when one uses this with a locale route constraint, so non-es routes can return a 404 on a Spanish website	false
force_locale	Force the locale to be added to all generated route paths, even for the default locale	false
generate_unlocalized_routes	Add translated routes without deleting original unlocalized versions. Note: Autosets force_locale to true	false
generate_unnamed_unlocalized_routes	Add the behavior of force_locale, but with a named default route which behaves as if generate_unlocalized_routes was true. root_path will redirect to /en or /es, depending on the value of I18n.locale	false
hide_locale	Force the locale to be hidden on generated route paths	false
host_locales	Set I18n.locale based on request.host. Useful for apps accepting requests from more than one domain. The key is a host pattern (supports wildcards for domains, subdomains, and TLDs), and the value is the locale symbol or string to use. See below for more details and examples.	{}
locale_param_key	The param key used to set the locale to the newly generated routes	:locale
locale_segment_proc	The locale segment of the url will by default be locale.to_s.downcase. You can supply your own mechanism via a Proc that takes locale as an argument, e.g. ->(locale) { locale.to_s.upcase }	false

Host-based Locale

If you have an application serving requests from more than one domain, you might want to set I18n.locale dynamically based on which domain the request is coming from.

The host_locales option is a hash mapping hosts to locales, with full wildcard support to allow matching multiple domains/subdomains/tlds. Host matching is case insensitive.

When a request hits your app from a domain matching one of the wild-card matchers defined in host_locales, the locale will be set to the specified locale. Unless you specified the force_locale configuration option to true, that locale will be hidden from routes (acting like a dynamic hide_locale option).

Here are a few examples of possible mappings:

RouteTranslator.config.host_locales =
  {                                # Matches:
    '*.es'                 => :es, # TLD:         ['domain.es', 'subdomain.domain.es', 'www.long.string.of.subdomains.es'] etc.
    'ru.wikipedia.*'       => :ru, # Subdomain:   ['ru.wikipedia.org', 'ru.wikipedia.net', 'ru.wikipedia.com'] etc.
    '*.subdomain.domain.*' => :ru, # Mixture:     ['subdomain.domain.org', 'www.subdomain.domain.net'] etc.
    'news.bbc.co.uk'       => :en, # Exact match: ['news.bbc.co.uk'] only
  }

In the case of a host matching more than once, the order in which the matchers are defined will be taken into account, like so:

RouteTranslator.config.host_locales = { 'russia.*' => :ru, '*.com'    => :en } # 'russia.com' will have locale :ru
RouteTranslator.config.host_locales = { '*.com'    => :en, 'russia.*' => :ru } # 'russia.com' will have locale :en

If host_locales option is set, the following options will be forced:

@config.force_locale                        = false
@config.generate_unlocalized_routes         = false
@config.generate_unnamed_unlocalized_routes = false
@config.hide_locale                         = true

This is to avoid odd behaviour brought about by route conflicts and because host_locales forces and hides the host-locale dynamically.

NOTE: locale from parameters has priority over the one from hosts.

Translations for similar routes with different namespaces

If you have routes that (partially) share names in one locale, but must be translated differently in another locale, for example:

get 'people/favourites', to: 'people/products#favourites'
get 'favourites',        to: 'products#favourites'

Then it is possible to provide different translations for common parts of those routes by scoping translations by a controller's namespace:

es:
  routes:
    favourites: favoritos
    controllers:
      people/products:
        favourites: fans

Routes will be translated as in:

people_products_favourites_es GET  /people/products/fans(.:format)       people/products#favourites {:locale=>"es"}
       products_favourites_es GET  /products/favoritos(.:format)         products#favourites {:locale=>"es"}

It is also possible to translated resources scoped into a namespace. Example:

namespace :people do
  resources :products, only: :index
end

es:
  routes:
    controllers:
      people/products:
        products: productos_favoritos

Routes will be translated as in:

people_products_es GET  /people/productos_favoritos(.:format)       people/products#index {:locale=>"es"}

The gem will lookup translations under controllers scope first and then lookup translations under routes scope.

Change locale parameter position in the path

If you need complex routing as /:country/:locale/path/to/some/pages, you can specify the position of your locale parameter in the following way:

scope ':country/:locale' do
  localized do
    root to: 'content#homepage'
  end
end

Using RouteTranslator with Devise

When using RouteTranslator with Devise, you may notice that some authentication-related flash messages (such as errors after failed logins) are shown in the wrong language. This happens because Devise builds some messages in middleware, after your controller’s actions have completed. If you use RouteTranslator’s around_action (or legacy around_filter) to set the locale, the locale is reset after the controller yields, and middleware like Devise will see the default locale.

This only affects you if Devise is mounted inside a localized block (for example, localized { devise_for :users }). If you do not use localized Devise routes, you do not need to change anything.

To ensure Devise’s middleware uses the correct locale, some users suggest replacing RouteTranslator’s around_action with a before_action. However, this is discouraged, as it can leave your application in the wrong locale after the request and may cause subtle bugs.

A better approach is to explicitly set the locale for Devise’s failure responses. Starting from Devise version 4.9.4, you can customize how Devise determines the locale for error messages, thanks to the ability to override the i18n_locale method in the failure app. This allows you to set the locale for Devise’s middleware without changing RouteTranslator’s recommended usage.

Here’s an example:

# config/initializers/devise.rb

Devise.setup do |config|
  # ...

  ActiveSupport.on_load(:devise_failure_app) do
    def i18n_locale
      RouteTranslator.locale_from_request(request)
    end
  end
end

Summary

• You only need this workaround if Devise is mounted in a localized block.
• Do not replace RouteTranslator’s around_action with a before_action.
• Instead, set the locale for Devise failure responses as shown above.
• The solution above requires Devise version 4.9.4 or higher, which allows customizing the i18n_locale method in the failure app.

Testing

Testing your controllers with routes-translator is easy, just add a locale parameter as String for your localized routes. Otherwise, an ActionController::UrlGenerationError will raise.

describe 'GET index' do
  it 'should respond with success' do
    # Remember to pass the locale param as String
    get :index, locale: 'fr'

    expect(response).to be_success
  end
end

Contributing

Please read through our contributing guidelines. Included are directions for opening issues, coding standards, and notes on development.

More over, if your pull request contains patches or features, you must include relevant unit tests.