Redirect 'myapp.com' to 'www.myapp.com' in rails without using htaccess?

class ApplicationController < ActionController::Base
  before_filter :check_uri

  def check_uri
    redirect_to request.protocol + "www." + request.host_with_port + request.request_uri if !/^www/.match(request.host)
  end
end

before_filter :check_uri

def check_uri
  if /^www/.match(request.host)
    redirect_to request.protocol + request.host_with_port[4..-1] + request.request_uri
  end
end

head :moved_permanently, :location => ‘http://www.newdomain.com’

def rails_301
headers["Status"] = "301 Moved Permanently"
redirect_to "http://www.newdomain.com"
end

def check_uri
  redirect_to request.protocol + "www." + request.host_with_port + request.request_uri if !/^www/.match(request.host) if Rails.env == 'production'
end