BeginForm<TController> won't post model first time round - asp.net-mvc

Question

I have an issue using the latest mvc futures BeginForm extension. I have disabled clientsidevalidation as I have read that there may still be a bug with it. Basically the first time it gets posted the model is null, the second time (and any time after that) it will post the model fine.
It works if I switch it back to #using(Html.BeginForm()) or #using(Html.BeginForm("action", "controller" etc but I would rather make use of the strongly typed version. Here is my code:
Controller
[HandleError]
public class HomeController : BaseServiceController<IUserService>
{
public HomeController(IUserService service, IMapper mapper, ICustomPrincipal user)
: base(service, mapper, user)
{}
[AllowAnonymous]
[HttpGet]
public ActionResult Logon(string ReturnUrl)
{
LogonModel model = new LogonModel() { ReturnUrl = ReturnUrl };
return View(model);
}
[AllowAnonymous]
[HttpPost]
public ActionResult Logon(LogonModel model)
{
if (!ModelState.IsValid)
{
return View(model);
}
SfUser sfUser = service.Logon(model.UserName, model.Password);
if (sfUser == null)
{
ModelState.AddModelError("General", "Username or Password incorrect");
return View(model);
}
Response.Cookies.Add(TicketMaster.setAuthCookie(new CustomPrincipalSerializeModel(sfUser)));
return Redirect(model.ReturnUrl);
}
View
#model LogonModel
#{
ViewBag.Title = "Logon";
}
//#using(Html.BeginForm()) //Works
#using(Html.BeginForm<HomeController>(c => c.Logon(Model)))
{
#Html.HiddenFor(m => m.ReturnUrl)
<div class="editor-label">
#Html.LabelFor(m => m.UserName)
</div>
<div class="editor-field">
#Html.TextBoxFor(m => m.UserName)
#Html.ValidationMessageFor(m => m.UserName)
</div>
<div class="editor-label">
#Html.LabelFor(m => m.Password)
</div>
<div class="editor-field">
#Html.PasswordFor(m => m.Password)
#Html.ValidationMessageFor(m => m.Password)
</div>
<br />
<p>
<input type="submit" value="Login" /><br />
#Html.ValidationSummary(true)
</p>
}
I could understand the problem if it always posted a null model, but only on first post? Driving me mad.

Answer 1

I know this is old and probably already solved somehow, but you should pass null instead of Model to the expression. That way, the model will be built using the form values.
It took me a few hours to find this. Go to the Strong Typed Html BeginForm<TController> section. This is the key point:
You want to pass your values within the form’s scope, not the
BeginForm method itself.
In your case, just change
#using(Html.BeginForm<HomeController>(c => c.Logon(Model)))
to
#using(Html.BeginForm<HomeController>(c => c.Logon(null)))