why model posted to action Display in view? - asp.net-mvc

Question

have 2 action with same name.(AddNewUser) one of them work with HttpGet and another with HttpPost.
[HTTPGet]
public ActionResult AddNewUser()
{
User user = Utilities.SessionProvider.GetCurrentUser();
if (user.ID_User == 0)
return Redirect("Apps.kosarfci.ir");
RoleType role = (RoleType)RoleDeterminer.RoleDeterminate();
if (role != RoleType.Center)
{
return RedirectToAction("Restriction");
}
return View("VNewUser");
}
[HttpPost]
public ActionResult AddNewUser(VMNewUser InModel)
{
User user = Utilities.SessionProvider.GetCurrentUser();
if (user.ID_User == 0)
return Redirect("Apps.kosarfci.ir");
RoleType role = (RoleType)RoleDeterminer.RoleDeterminate();
if (role != RoleType.Center)
{
return RedirectToAction("Restriction");
}
IUserBL centerUserBL = new CenterUserBL();
InModel.User.UserName = InModell.User.NationalCode;
InModel.User.Password = InModell.User.PersonalCode;
bool confirmedBL = centerUserBL.AddUser(InModel.User);
_msgList.Add(new Message() { MsgType = MessageType.Success, MsgContent = MessageProvider.GetMessage(MessageContent.Submit_Success_NewUser) });
ViewBag.Message = _msgList;
return View("VNewUser");
}
AddNewUser() ,return a form with input entry and then form submited to AddNewUser(VMNewUser InModel). but after that a form with filled entry with posted model is displayed. i expect that a form with blank input entry display because i dont send pre-filled model(VMNewUser) in to the view.
why?
--VMNewUser--
#model PersonManagement.Views.User.VMNewUser
<style>
table{
font-family:Tahoma;
}
</style>
#using (Html.BeginForm("AddNewUser", "User", FormMethod.Post))
{
<table>
<tr>
<td>name</td>
<td>#Html.TextBoxFor(f=>f.User.FirstName)</td>
</tr>
<tr>
<td>family</td>
<td>#Html.TextBoxFor(f=>f.User.LastName)</td>
</tr>
<tr>
<td>personalcode</td>
<td>#Html.TextBoxFor(f=>f.User.PersonalCode)</td>
</tr>
<tr>
<td>nationalcode</td>
<td>#Html.TextBoxFor(f=>f.User.NationalCode)</td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="create" style="font-family:Tahoma;float:left" /></td>
</tr>
</table>
}

Answer 1

The main reason for sending back the populated model is to prevent the user from having to re-populate the form if there is an error processing the request server-side. It also provides the client with information about what fields failed and if there are any particular error messages that should be displayed.
It's recommended you use the PRG pattern therefore if the request is successful, you would redirect the user to a new page. In your case, you could redirect the user back to AddNewUser action which would present the user with the empty form again e.g.
return RedirectToAction("AddNewUser");

Answer 2

Way 1:
In your HttpPost method return to Action instead of returning view like this:
return RedirectToAction("AddNewUser");
Way 2:
or simply return View() without passing Model object which means null model and the fields will not be populated obviously:
return View();
Way 3 :
you can also do like this, if Model is valid save data and return View with empty fields, otherwise return view with populated data to user.
Like this :
[HttpPost]
public ActionResult AddNewUser(VMNewUser InModel)
{
if(ModelState.IsValid)
{
User user = Utilities.SessionProvider.GetCurrentUser();
if (user.ID_User == 0)
return Redirect("Apps.kosarfci.ir");
RoleType role = (RoleType)RoleDeterminer.RoleDeterminate();
if (role != RoleType.Center)
{
return RedirectToAction("Restriction");
}
IUserBL centerUserBL = new CenterUserBL();
InModel.User.UserName = InModell.User.NationalCode;
InModel.User.Password = InModell.User.PersonalCode;
bool confirmedBL = centerUserBL.AddUser(InModel.User);
_msgList.Add(new Message() { MsgType = MessageType.Success, MsgContent = MessageProvider.GetMessage(MessageContent.Submit_Success_NewUser) });
ViewBag.Message = _msgList;
return View();
}
else
{
return View(InModel);
}
}