Localized routes in Rails: tips and tricks

  scope "/:locale", locale: /#{I18n.available_locales.join("|")}/ do
    resources :posts
    root to: redirect("/%{locale}/posts", status: 302)
  end
  root to: redirect("/#{I18n.default_locale}", status: 302), as: :redirected_root
  get "/*path", to: redirect("/#{I18n.default_locale}/%{path}", status: 302), constraints: {path: /(?!(#{I18n.available_locales.join("|")})/).*/}, format: false

Let's take a look at the above code sample from config/routes.rb and will study what it does line by line.