POST Action Losing Values - asp.net-mvc

Question

I populate my view with model values for UseCaseId and ExtensionPoint - debugging through this seems to work fine.
However, when I add a new bit of information to the ExtensionTitle field on my view and then POST, only the value for ExtensionTitle is retained and the values for UseCaseId and ExtensionPoint are lost. This means that if (ModelState.IsValid) returns false and therefore I can't save the new record to the database.
Can anyone tell me why these values are getting lost when I POST?
VIEWMODEL
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Web;
namespace JustSpecIt.ViewModels
{
public class AddExtensionStepViewModel
{
public int UseCaseId { get; set; }
[DisplayName ("Extends Step #")]
public int ExtensionPoint { get; set; }
[DisplayName ("Extends Step Description")]
public string StepTitle { get; set; }
[DisplayName("Extension Name")]
public string ExtensionTitle { get; set; }
}
}
MODEL
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace JustSpecIt.Models
{
public class Extension
{
public int ID { get; set; }
public int UseCaseID { get; set; }
public string Title { get; set; }
public int ExtensionPoint { get; set; }
}
}
CONTROLLER
// GET: Extensions/Create
public ActionResult Create(int id)
{
ViewBag.UseCaseId = id;
ViewBag.StepTitle = db.Steps.Find(id).Content;
//Create an populate the ViewModel
AddExtensionStepViewModel model = new AddExtensionStepViewModel()
{
ExtensionPoint = id,
UseCaseId = db.Steps.Find(id).UseCaseID,
};
return View();
}
// POST: Extensions/Create
// To protect from overposting attacks, please enable the specific properties you want to bind to, for
// more details see http://go.microsoft.com/fwlink/?LinkId=317598.
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Include = "UseCaseId,ExtensionTitle,ExtensionPoint")] AddExtensionStepViewModel model)
{
if (ModelState.IsValid)
{
Extension e = new Extension ();
e.ExtensionPoint = model.ExtensionPoint;
e.UseCaseID = model.UseCaseId;
e.Title = model.ExtensionTitle;
db.Extensions.Add(e);
db.SaveChanges();
return RedirectToAction("ChooseExtensionStep", new { id = model.UseCaseId });
}
return View(model);
}
VIEW
#model JustSpecIt.ViewModels.AddExtensionStepViewModel
#{
ViewBag.Title = "Create";
Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>Add Extension Step</h2>
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
#Html.HiddenFor(model => model.UseCaseId)
#Html.HiddenFor(model => model.ExtensionPoint)
<div class="form-horizontal">
<h4>Extension</h4>
<hr />
#Html.ValidationSummary(true, "", new { #class = "text-danger" })
<div class="form-group">
#Html.LabelFor(model => model.ExtensionTitle, htmlAttributes: new { #class = "control-label col-md-4" })
<div class="col-md-10">
#Html.EditorFor(model => model.ExtensionTitle, new { htmlAttributes = new { #class = "form-control form-control-no-max-width" } })
#Html.ValidationMessageFor(model => model.ExtensionTitle, "", new { #class = "text-danger" })
</div>
</div>
<div class="form-group">
<div class="col-md-offset-2 col-md-10">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</div>
</div>
}

Answer 1

You have not passed the model to the view in your GET method (so the values of UseCaseID and Title are 0 (the defaults for int)
public ActionResult Create(int id)
{
ViewBag.UseCaseId = id;
ViewBag.StepTitle = db.Steps.Find(id).Content;
AddExtensionStepViewModel model = new AddExtensionStepViewModel()
{
ExtensionPoint = id,
UseCaseId = db.Steps.Find(id).UseCaseID,
};
return View(model); // change this
}