Authorize attribute and jquery AJAX in asp.net MVC

I have used jquery ajax function to submit a form. The users have to be logged in else they must redirect to a login page.I have used Authorize() attribute for it.

[Authorize]
public ActionResult Creat()
{
....
}

If the user is not login the action return login page to jquery's ajax functions and it is displayed on the same page but I want to redirect the user to login page. Is there any solution?

Working example: https://github.com/ronnieoverby/mvc-ajax-auth

Important parts:

AjaxAuthorizeAttribute:

using System.Web.Mvc;

namespace MvcApplication1
{
    public class AjaxAuthorizeAttribute : AuthorizeAttribute
    {
        protected override void HandleUnauthorizedRequest(AuthorizationContext context)
        {
            if (context.HttpContext.Request.IsAjaxRequest())
            {
                var urlHelper = new UrlHelper(context.RequestContext);
                context.HttpContext.Response.StatusCode = 403;
                context.Result = new JsonResult
                {
                    Data = new
                    {
                        Error = "NotAuthorized",
                        LogOnUrl = urlHelper.Action("LogOn", "Account")
                    },
                    JsonRequestBehavior = JsonRequestBehavior.AllowGet
                };
            }
            else
            {
                base.HandleUnauthorizedRequest(context);
            }
        }
    }
}

Javascript:

    $(function () {
        $(document).ajaxError(function (e, xhr) {
            if (xhr.status == 403) {
                var response = $.parseJSON(xhr.responseText);
                window.location = response.LogOnUrl;
            }
        });
    });

Use the attribute in a controller:

    [AjaxAuthorize]
    public ActionResult Secret()
    {
        return PartialView();
    }

Do some ajax:

@Ajax.ActionLink("Get Secret", "Secret", new AjaxOptions { UpdateTargetId = "secretArea", })

<div id="secretArea"></div>

Just a handy addition to #Ronnie's answer

if you want to keep the page url on redirect.

 var pathname = window.location.pathname;
        if (xhr.status == 403) {
                var response = $.parseJSON(xhr.responseText);
                window.location = response.LogOnUrl + '?ReturnUrl=' + pathname;
            }