Rails 3.1 Routes: How to add a locale to beginning of URI when missing?

I'm trying to insert a locale at the beginning of a request URI in a Rails 3.1 app if it is missing. I created a Ruby script that does what I want:

uri = "/products"
re  = /\A\/((?:[a-z]{2,2})(?:[-|_](?:[A-Z]{2,2}))?)(\/.*)\Z/

unless uri =~ re
  uri = "/en#{uri}"
end

puts uri

So, if the request URI is /en-GB/products (the locale is already present), it doesn't do anything. If it is /products (like the example above), it spits out /en/products.

Now I'm trying to get it to work in my routes file. Here's what I'v开发者_JS百科e attempted:

match "(*all)", :to => redirect do |params, request|
  uri = request.path_info
  re  = /\A\/((?:[a-z]{2,2})(?:[-|_](?:[A-Z]{2,2}))?)(\/.*)\Z/

  unless uri =~ re
    uri = "/en#{uri}"
  end

  "#{request.scheme}://#{request.host_with_port}#{uri}"
end

My problem is that I can't even get inside the match block. I keep getting an ArgumentError: redirection argument not supported.

I've tried changing it to match "(*all)" => redirect do |params, request| to no avail.

I'm looking at the Rails 3.1 API documentation for these examples.

Is the routes file the place to try and do this? It makes the most sense to me.

---

Introducing logic in routes smells for me. Controllers are meant for that, and I would use optional scope in routes and before_filter in controller with redirect_to

routes.rb - keep it simple:

scope '(:locale)', :constraints => {:locale=> /[a-z]{2}(-[A-Z]{2})?/ } do
  match 'url1' ...
  match 'other' ...
end

controller:

before_filter :check_locale

protected

def check_locale
  redirect_to "/en#{request.path_info}" if params[:locale].blank?
end

(the above is written from memory)

---

I find these lines in a before_filter in the ActionController quite usefull. These lines extracts a locale an redirects e.g. foo.com/fie to foo.com/en/fie (or wahtever locale the current locale is). If the user has a not supported locale, he gets a hint, that he can gon on with english...

def set_locale
  params_locale = params[:locale]
  if params_locale
    if (!Supportedlocale::SUPPORTED.include?(params_locale))
      redirect_to "/en/localenotsupported/"
    end
  end
  language_locale = locale_from_accept_language
  default_locale = I18n.default_locale
  I18n.locale = params_locale || language_locale || default_locale

  if params_locale.blank?
    redirect_to "/#{I18n.locale}#{request.path_info}"
  end
end


def locale_from_accept_language
  accepted_lang = request.env['HTTP_ACCEPT_LANGUAGE']
  if (!accepted_lang.nil?)
    accepted_lang.scan(/^[a-z]{2}/).first
  else
    "en" #en is default!
  end
end

---

In order to keep parameter like pagination do something like :

def check_locale
  if params[:locale].blank?
    I18n.locale = :en 
    redirect_to params.merge!(:locale => I18n.locale)
  end
end

So

/controler/action?page=10&search=dada => /en/controler/action?page=10&search=dada