Route values disappeare in View .Net MVC3 - asp.net-mvc-3

Question

I have simple controller:
public class TestController : Controller
{
public ActionResult Test(string r)
{
return View();
}
}
I have simple View Test.cshtml:
<h2>#ViewContext.RouteData.Values["r"]</h2>
#using (Html.BeginForm("Test", "Test"))
{
<input type="text" name="r" />
<button>Submit</button>
}
I have route rule in Global.asax:
routes.MapRoute(
null,
"Test/{r}",
new { action = "Test", controller = "Test",
r = UrlParameter.Optional }
);
I want to make such thing: user types route value in input, press submit and controller redirects him to page Test/value. But controller show just page with name Test everytime. ViewContext.RouteData.Values["r"] is empty too. I check in debug, Test action recieves user value of r correctly.
How can I realize my idea?
Thanks.

Answer 1

I'm super late to the party, but just wanted to post a solution for reference. Let's assume that this form has more than just a strong as it's input. Assuming there are other inputs, we can wrap up the inputs of the form into a class in our model, called TestModel whose properties maps to the id's of the form's inputs.
In our post, we redirect to the get, passing in the route values we need in the URL. Any other data can then be shuttled to the get using a TempData.
public class TestController : Controller
{
[HttpGet]
public ActionResult Test(string r)
{
TestModel model = TempData["TestModel"] as TestModel;
return View(model);
}
[HttpPost]
public ActionResult Test(string r,TestModel model) //some strongly typed class to contain form inputs
{
TempData["TestModel"] = model; //pass any other form inputs to the other action
return RedirectToAction("Test", new{r = r}); //preserve route value
}
}

Answer 2

You cannot do this without javascript. There are two types of methods that exist when submitting a <form>: GET and POST. When you use POST (which is the default), the form is POSTed to the url but all data entered in input fields is part of the POST body, so it is not part of the url. When you use GET, the input fields data is part of the query string but of the form /Test?r=somevalue.
I wouldn't recommend you trying to send user input as part of the path but if you decide to go that route you could subscribe to the submit event of the form and rewrite the url:
$('form').submit(function() {
var data = $('input[name="r"]', this).val();
window.location.href = this.action + '/' + encodeURIComponent(data);
return false;
});

Answer 3

As far as you are saying to post the form to Html.BeginForm("Test", "Test") you will be always posted back to the same page.
A solution could be to use an explicit Redirect to the action using 'RedirectToAction' (in view) or you can use javascript to change the form's action:
<input type="text" name="r" onchange="this.parent.action = '\/Test\/'+this.value"/>