title: MVC3 Razor - How to pass data from controller to view - and back to controller
body: <p>I have a view where everything will be populated by the user - but relates to a parent entity.  I pass that Id to my view using ViewBag, but I don't know how to get it back to the post action in the controller.  I have tried hidden form fields, but it isn't showing in the post, or I do not know how to grab it...
  Controller:</p>
  
  <pre><code>public ActionResult AddCar(int id)
  {
  ViewBag.Id = id;
  return View();
  }
  </code></pre>
  
  <p>View (tried):</p>
  
  <pre><code>    @using (Html.BeginForm("AddReturn", "DealerAdmin", new { id = carId }))
      {
  View (tried):
       @Html.Hidden(carId.ToString())
  </code></pre>
  
  <p>HOw do I retrieve the value in my post action in my controller?  Or is there a better/different way to approach it?
  THanks</p>