Permanent redirects in routes.rb, while preserving query-string args

routes.rb

# take care of old, legacy routes
redirect_with_query_string = lambda do |path|
  redirect do |params, req|
    path << "?#{req.query_string}" unless req.query_string.blank?
    path
  end
end

# example usage
match 'legacy_root_path'   => redirect_with_query_string.call('/')
match 'studios/props'      => redirect_with_query_string.call('/studios/gear')