Passing null values to the parameter in controller after submit? - asp.net-mvc-3

Question

The below code is sample I typed
After I submit passing null values to controller, In Controller I have used the Class name then value passing correctly but when i used the parameter it passing NULL values to the controller. Please give me a solution..
Controller:
[HttpGet]
public ActionResult Index()
{
return View();
}
[HttpPost]
public ActionResult Index(string firstname)
{
LogonViewModel lv = new LogonViewModel();
var ob = s.Newcustomer(firstname)
return View(ob );
}
View:
#model IList<clientval.Models.LogonViewModel>
#{
ViewBag.Title = "Index";
}
#using (Html.BeginForm())
{
for (int i = 0; i < 1; i++)
{
#Html.LabelFor(m => m[i].UserName)
#Html.TextBoxFor(m => m[i].UserName)
#Html.ValidationMessageFor(per => per[i].UserName)
<input type="submit" value="submit" />
}
}
Model:
public class LogonViewModel
{
[Required(ErrorMessage = "User Name is Required")]
public string UserName { get; set; }
}
public List<ShoppingClass> Newcustomer(string firstname1)
{
List<ShoppingClass> list = new List<ShoppingClass>();
..
}

Answer 1

This:
[HttpGet]
public ActionResult Index() {
return View();
}
Does not give you this in your view:
#model IList<clientval.Models.LogonViewModel>
And this:
for (int i = 0; i < 1; i++) {
#Html.LabelFor(m => m[i].UserName)
#Html.TextBoxFor(m => m[i].UserName)
#Html.ValidationMessageFor(per => per[i].UserName)
<input type="submit" value="submit" />
}
Will not work with this:
[HttpPost]
public ActionResult Index(string firstname) {
LogonViewModel lv = new LogonViewModel();
var ob = s.Newcustomer(firstname)
return View(ob );
}
You're not sending a model to your view, and you're using a list in your view, but expecting a single string value in you controller. Something is very strange/wrong with your example, or your code.
Why do you have a IList as your model? If all you need is to render a form with a single input field. You should have code like this:
[HttpGet]
public ActionResult Index() {
return View(new LogonViewModel());
}
And the view:
#model clientval.Models.LogonViewModel
#using (Html.BeginForm())
{
#Html.LabelFor(m => m.UserName)
#Html.TextBoxFor(m => m.UserName)
#Html.ValidationMessageFor(m => m.UserName)
<input type="submit" value="submit" />
}
And the second action on the controller:
[HttpPost]
public ActionResult Index(LogonViewModel model) {
if (ModelState.IsValid) {
// TODO: Whatever logic is needed here!
}
return View(model);
}

Answer 2

Its working.. I have changed my controller as written below
Controller:
[HttpGet]
public ActionResult Index()
{
return View();
}
[HttpPost]
public ActionResult Index(IList<LogonViewModel> obj)
{
LogonViewModel lv = new LogonViewModel();
var ob = lv.Newcustomer(obj[0].FirstName)
return View(ob );
}