Reference DropDownList selected value from enclosing Form - asp.net-mvc

Question

I'm just getting started with MVC5 (from WebForms), and dropdownlist bindings are giving me some fits.
I'd like to get this working using a GET request back to the page, with a selected value parameter. I'm hopeful that I can specify the route arguments in the form itself, so I'd like to reference the DDL's SelectedValue.
<p>
#using (Html.BeginForm("Index", "Profile", FormMethod.Get, new { id = WHATDOIPUTHERE} )) {
#Html.AntiForgeryToken()
#Html.DropDownList("ApplicationID", new SelectList(ViewBag.ApplicationList, "ApplicationID", "ApplicationName", ViewBag.SelectedApplicationId), new {onchange = "this.form.submit();"})
}
</p>
I can make it work with a POST form, but that requires a second controller method so I end up with
public ActionResult Index(long? id) {
ConfigManager config = new ConfigManager();
//handle application. default to the first application returned if none is supplied.
ViewBag.ApplicationList = config.GetApplications().ToList();
if (id != null) {
ViewBag.SelectedApplicationId = (long)id;
}
else {
ViewBag.SelectedApplicationId = ViewBag.ApplicationList[0].ApplicationID; //just a safe default, if no param provided.
}
//handle profile list.
List<ProfileViewModel> ps = new List<ProfileViewModel>();
ps = (from p in config.GetProfilesByApp((long)ViewBag.SelectedApplicationId) select new ProfileViewModel(p)).ToList();
return View(ps);
}
//POST: Profile
//read the form post result, and recall Index, passing in the ID.
[HttpPost]
public ActionResult index(FormCollection collection) {
return RedirectToAction("Index", "Profile", new {id = collection["ApplicationId"]});
}
It would be really nice to get rid of the POST method, since this View only ever lists child entities.
What do you think?

Answer 1

You can update your GET action method parameter name to be same as your dropdown name.
I also made some small changes to avoid possible null reference exceptions.
public ActionResult Index(long? ApplicationID) {
var config = new ConfigManager();
var applicationList = config.GetApplications().ToList();
ViewBag.ApplicationList = applicationList ;
if (ApplicationID!= null) {
ViewBag.SelectedApplicationId = ApplicationID.Value;
}
else
{
if(applicationList.Any())
{
ViewBag.SelectedApplicationId = applicationList[0].ApplicationID;
}
}
var ps = new List<ProfileViewModel>();
ps = (from p in config.GetProfilesByApp((long)ViewBag.SelectedApplicationId)
select new ProfileViewModel(p)).ToList();
return View(ps);
}