Null object from view in ASP.NET MVC Form - asp.net-mvc

Question

I'm building a simple inventory application where the user create an order by selecting the items he wants to be delivered, fill a form with the name of the recipient and then the order get processed.
First of all I have an OrdineScarico class that stores a collection of InventoryItems to be processed (like a cart), a DeliverDetails class that stores the recipient name
public class OrdineScarico
{
private List<SingoloOrdine> ordineCollection = new List<SingoloOrdine>();
// collection methods
}
public class SingoloOrdine
{
public InventoryItem InventoryItem { get; set; }
public int Qty { get; set; }
}
public class DeliverDetails
{
[Required(ErrorMessage = "Inserire il nome del ricevente")]
public string Nome { get; set; }
}
and then a ConfermaScaricoViewModel class -in a different namespace- for wrapping them up
public class ConfermaScaricoViewModel
{
public OrdineScarico OrdineScarico { get; set; }
public DeliverDetails DeliverDetails { get; set; }
}
I have these action methods in the ScaricoController
public ViewResult Conferma()
{
return View(
new ConfermaScaricoViewModel
{
OrdineScarico = GetScarico(),
DeliverDetails = new DeliverDetails()
});
}
[HttpPost]
public ViewResult Conferma(ConfermaScaricoViewModel viewModel)
{
if (ModelState.IsValid)
{
repositoryProcessor.ScaricaItem(viewModel.OrdineScarico, viewModel.DeliverDetails);
viewModel.OrdineScarico.Clear();
return View("Confermato");
}
else
{
return View(
new ConfermaScaricoViewModel
{
OrdineScarico = GetScarico(),
DeliverDetails = new DeliverDetails()
});
}
}
where GetScarico() reads the OrdineScarico instance from the active session
private OrdineScarico GetScarico()
{
OrdineScarico scarico = (OrdineScarico)Session["Scarico"];
if (scarico == null)
{
scarico = new OrdineScarico();
Session["Scarico"] = scarico;
}
return scarico;
}
This is the view code:
#model GestioneMagazzino.WebUI.Models.ConfermaScaricoViewModel
#{
ViewBag.Title = "Conferma";
}
<h2>Conferma scarico</h2>
#using (Html.BeginForm())
{
#Html.ValidationSummary()
<div class="form-group col-md-12">
<div class="row">
<label class="text-left">Ricevente:</label>
</div>
<div class="row">
#Html.TextBoxFor(model => model.DeliverDetails.Nome, new { #class="col-md-7" })
</div>
</div>
<div>
<input class="btn btn-primary" type="submit" value="Conferma" />
</div>
}
The problem is that when the POST action method is called, I get a null value for the OrdineScarico argument, and the ModelState is always false. I also tried adding an hidden field
#Html.HiddenFor(model => model.OrdineScarico)
but the OrdineScarico argument is always null when the POST method is called, while it's not when the controller renders the view.
Thanks,
Davide.

Answer 1

you must use #Html.HiddenFor(model => model.OrdineScarico)
also may be DeliverDetails has other field that you must set value for it.
you can use break point on line :
if (ModelState.IsValid)
in method post of Conferma.
run code and when code arrived to break point,
move cursor to the ModelState and wait to see data in it.
on values check all entities and find which property has error and you can see the message of error.
edit: cause you have not send any data for OrdineScarico. so it will be null in post action.
the OrdineScarico has a list member so
you should add this.
<input hidden name="OrdineScarico.ordineCollection[]" value="#value">