Object reference not set to an instance of an object in MVC - asp.net-mvc

Question

I looked at all of the postings with this error but none helps. I am using MVC with the views in ASPX (C#).
I am updating records in the database after editing the data in simple views. When I process one record at a time (Controller EDIT methods and EDIT view) all works fine.
When I process multiple records (Controller UpdateTest and UPDATETEST view) I get an error in my HTTPPOST method in Controller after clicking the Submit button in a view.
here is an error with the sample codes one which works and one which does not:
Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Source Error: (CONTROLLER – SEE BELOW HttpPost UpdateTest(ICollection<Mysurvey> mysurveys)
enter code here
Line 48: public ActionResult UpdateTest(ICollection<Mysurvey> mysurveys)
Line 49: {
Line 50: foreach (var survey in mysurveys)
Line 51: {
Line 52: db.Entry(survey).State = EntityState.Modified;
Source File: C:\Users\rsc_vok\Documents\Visual Studio 2010 \Projects\MvcMysurvey\MvcMysurvey\Controllers\MysurveyController.cs Line: 50
CONTROLLER
namespace MvcMysurvey.Controllers
{
THE CODE WHICH WORKS – SINGLE EDIT
public ActionResult Edit(int id)
{
Mysurvey mysurvey = db.Mysurveys.Find(id);
return View(mysurvey);
}
// POST: /Mysurvey/Edit/5
[HttpPost]
public ActionResult Edit(Mysurvey mysurvey)
{
System.Diagnostics.Debug.WriteLine("iam in edit post");
if (ModelState.IsValid)
{
db.Entry(mysurvey).State = EntityState.Modified;
db.SaveChanges();
return RedirectToAction("Index");
}
return View(mysurvey);
}
THE CODE WITH THE ERROR IN httppost – MULTIPLE RECORDS SAVE
public ActionResult UpdateTest(int id = 0)
{
List<Mysurvey> mysurveys = db.Mysurveys.ToList();
return View(mysurveys.ToList());
}
[HttpPost]
public ActionResult UpdateTest(ICollection<Mysurvey> mysurveys)
{
foreach (var survey in mysurveys)
{
db.Entry(survey).State = EntityState.Modified;
}
db.SaveChanges();
return View(mysurveys);
}
VIEW
UPDATETEST
THE CODE WHICH WORKS HERE BUT THROWS AN ERROR IN CONTROLLER AFTER THE SAVE BUTTON IS HIT
<%# Page Language="C#" MasterPageFile="~/Views/Shared/Site.master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<MvcMysurvey.Models.Mysurvey>>" %>
<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
Updatetest
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
<script src="<%: Url.Content("~/Scripts/jquery.validate.min.js") %>" type="text/javascript"></script>
<script src="<%: Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js") %>" type="text/javascript"></script>
<% using (Html.BeginForm()) { %>
<%: Html.ValidationSummary(true) %>
<fieldset>
<legend>Mysurvey</legend>
<% foreach (var item in Model) { %>
<%: Html.HiddenFor(model => item.ID) %>
<%: Html.HiddenFor(model => item.SurveyID) %>
<div class="editor-label">
<%: Html.LabelFor(model => item.Comment) %>
</div>
<div class="editor-field">
<%: Html.EditorFor(model => item.Comment) %>
<%: Html.ValidationMessageFor(model => item.Comment) %>
</div>
<%} %>
<p>
<input type="submit" value="Save" />
</p>
</fieldset>
<% } %>
<div>
<%: Html.ActionLink("Back to List", "Index") %>
</div>
</asp:Content>
MODEL
namespace MvcMysurvey.Models
{
public class Mysurvey
{
public int ID { get; set; }
[DisplayFormat(DataFormatString = "{0:c}")]
public int SurveyID { get; set; }
public string Comment { get; set; }
}
public class MysurveyDBContext : DbContext
{
public DbSet<Mysurvey> Mysurveys { get; set; }
}
}