ASP.Net MVC partial views keeping their model state?

Question

This is probably again a newbie question.

When I create an ASP.NET MVC2 application, an Account Controller with an Action LogIn is created like this:

[HttpPost]
public ActionResult LogOn(LogOnModel model, string returnUrl)
{
   if (ModelState.IsValid)
   {
      if (MembershipService.ValidateUser(model.UserName, model.Password))
      {
         FormsService.SignIn(model.UserName, model.RememberMe);
         if (!String.IsNullOrEmpty(returnUrl))
         {
            return Redirect(returnUrl);
         }
         else
         {
           return RedirectToAction("Index", "Home");
         }
       }
       else
       {
          ModelState.AddModelError("", "The user name or password provided is incorrect.");
       }
     }

        // If we got this far, something failed, redisplay form
        return View(model);
    }

Now, I don't want to have a login page, I want to have login controls as part of a bigger page. So, I changed Login.aspx to Login.ascx and I am integrating it in my main view either with Html.RenderPartial or Html.RenderAction.

Both works like a charm if the login is successfull. If it is not, the

return View(model)

is killing me. What I want is to go back to my main page (call it Home/Index) but with the error information of the partial view.

return RedirectToAction("Index", "Home")

Obviously doesn't work.

Hints?

Answer 1

Yeah redirecttoaction but provide an error message with it in the tempdata so you should do something like this

TempData["errorMsg"] = "incorrect values provided";
return RedirectToAction("Index", "Home")

Of course in the main index you should have a div that displays the message

<%= html.Encode(TempData["errorMsg"]) %>

EDIT I see you want to maintain the modelstate that might be a problem but what you could do is pass the modelstate in the index action or pass the modelstate object in the tempdata. What you can do then is check if a there are modelstate errors in the object and if there are check the field and add the error to the right field.

Answer 2

You could explicitly specify the view to return:

return View("~/Views/Home/Index.aspx", model);

This way error information will be preserved and correct view rendered.

Answer 3

Take a look at practice #13 on this blog. This method works well to pass modelstate information when you're coding in the PRG (Post-Redirect-Get) style. You'll just need to create a couple of action filters and apply them to your get and post actions as appropriate.