I have simple view in ASP.NET 4:

```
<form action="GetWeather" method="post">
    <input name="city" type="text" />
    <input type="submit" />
</form>
<h1>@ViewBag.City</h1>

```

And simple controller which was supposed to display input from the form on the same page:

```
public class WeatherController : Controller
{
    string cityName = "TBD";
    public ActionResult Index()
    {
        ViewBag.City = cityName;
        return View();
    }

    [HttpPost]
    public ActionResult GetWeather(string city)
    {
        cityName = city;
        return Redirect("/Weather/Index");
    }
}

```

After submit I keep getting my `"TBD"` string. I couldn't find anything about it, as everything is based on model, which I don't need.