Rails routes with optional scope ":locale"

I finally figured out how to do it easily. You just have to set the default_url_options in the app controller as below.

  def default_url_options(options={})
    { :locale => I18n.locale == I18n.default_locale ? nil : I18n.locale  }
  end

This way, you are sure the locale isn't sent to the path helpers.

This SHOULD be a better solution:

In your routes.rb,

scope "(:locale)", locale: /#{I18n.available_locales.join("|")}/, defaults: {locale: "en"} do

As MegaTux said, set defaults: {locale: "en"} in the scope.

The advantage: The jlfenaux solution works in most contexts, but not all. In certain contexts (like basically anything outside of your main controllers and views), the path helpers will get confused and put the object or object.id in the locale parameter, which will cause errors. You'll find yourself putting locale: nil in lots of path helpers to avoid those errors.

The possible problem: It seems that defaults: {locale: "en"} always overrides any other value you pass in for locale. The option is named default, so I'd expect it to assign locale to 'en' only when there's no value already, but that's not what happens. Anyone else experiencing this?