Asp.net mvc 对象引用未设置为MVC中对象的实例

我查看了所有带有此错误的帖子，但没有任何帮助。我正在使用MVC和ASPX C中的视图。 在简单视图中编辑数据后，我正在更新数据库中的记录。当我一次处理一条记录时，控制器的编辑方法和编辑视图都可以正常工作。 当我处理多个记录Controller UpdateTest和UpdateTest视图时，在单击视图中的Submit按钮后，我在Controller中的HTTPPOST方法中得到一个错误

以下是示例代码的一个错误，一个有效，一个无效：

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

控制器

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);
    }

看法

模型

---

您没有编写Html.BeginForm参数。它在没有参数的情况下工作吗？您使用的是强类型视图吗？AliRiza-我是新手，但我相信由于MVC，它会自动返回到重载的[httppost]控制器方法，我可以看到，因为该方法中发生了错误。答案发布在以下链接：

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>

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; }
}
}