Only POSTs with both ActionLink and submit button; redirects otherwise

Question

I'm trying to setup a simple form submission in MVC5, but I'm finding that my method doesn't get fired unless I have both an ActionLink and submit button.

I have a simple model:

public class LoginModel
{
    public string username { get; set; }
}

Then I have two methods in my controller, one for when a form submission is available and one when not:

[HttpGet]
public ActionResult Login()
{
    return View();
}

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Login(LoginModel myModel)
{ 
    var username = myModel.username;

    // do something with username

    return View();
}

Finally, my View creates a POSTing form:

@using (Html.BeginForm("Login", "Home", FormMethod.Post))
{
    @Html.AntiForgeryToken()
    @Html.TextBox("username", string.Empty)

    @Html.ActionLink("Enter", "Login")
    <input type="submit" name="submit" value="Enter" />
}

I don't really care whether I use an ActionLink or whether I have a submit button (MSDN implies it should be the latter), but if I have only one of them, my [HttpPost] method is not called, and my page is redirected with the username in the query string:

/Home/Login?ReturnUrl=%2F%3Fusername%3DmyUsernameHere

If I have both on the page, I can click the ActionLink and I see that the appropriate method is called with myModel.username containing the value I provided. The submit button, however, will still redirect.

I want this form method to be POST, not GET (which it is in the generated HTML), and for failures to not contain the key as a GET param. What's the problem with having only one of these form submission mechanisms? Why do they not trigger the POST as expected? Is there something more I need to do to 'register' my model with the view, even though it is submitted properly in my workaround scenario?

Edit -- My configured routes are typically as follows:

routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
    name: "Default",
    url: "{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
routes.RouteExistingFiles = true;

So normally, I'm going to /Login instead of /Home/Login.

Also, I do have some authentication setup, with my HomeController decorated with [Authorize] and my Login methods both with [AllowAnonymous]. When I remove all annotations, I still find that my [HttpPost] is not called, and username shows up as a GET parameter instead of being POSTed.

Answer 1

I believe that the application doesn't understand that you're trying to make a model with just username. So, you are sending a string username and attempting to place it into a model. I'm not entirely sure about that. Could you try binding your form to your model? Here's an example:

View:

@model YourApplication.Models.LoginModel

@using (Html.BeginForm("Login", "Home"))
{
    @Html.AntiForgeryToken()
    @Html.TextBoxFor(model => model.username, string.Empty)

    <input type="submit" value="Enter" />
}

Controller:

[HttpGet]
public ActionResult Login()
{
    return View();
}

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Login([Bind(Include="username")] LoginModel myModel)
{ 
    var username = myModel.username;

    // do something with username

    return View("Congrats");
}

Here's an alternate option. If you wanted to do something else, maybe try accepting the string "username" and creating your model after? Example:

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Login(string username)
{ 
    LoginModel myModel = new LoginModel();
    myModel.username = username;

    // do something with username

    return View("Congrats");
}

Either way, you should be using the submit button.