Question

CONTROLLER

我正在为表添加分页和排序。用户变量已成功填充记录列表。我的问题是这段代码给出了“在App_Web_aa2wbzst.dll中发生了类型'System.NullReferenceException'的异常，但未在用户代码中处理”。这是视图的前两行。

private UserBs objBs;
        public ListUserController()
        {
            objBs = new UserBs();
        }
        // GET: Admin/ListUser
        public ActionResult Index(String SortOrder, String SortBy, String Page)
        {
            ViewBag.SortOrder = SortOrder;
            ViewBag.SortBy = SortBy;
            var users = objBs.GetALL();
            switch (SortBy)
            {
                case "UserEmail":
                    switch (SortOrder)
                    {
                        case "Asc":
                            users = users.OrderBy(x => x.UserEmail).ToList();
                            break;
                        case "Desc":
                            users = users.OrderByDescending(x => x.UserEmail).ToList();
                            break;
                        default:
                            break;
                    }
                    break;
                case "Role":
                    switch (SortOrder)
                    {
                        case "Asc":
                            users = users.OrderBy(x => x.Role).ToList();
                            break;
                        case "Desc":
                            users = users.OrderByDescending(x => x.Role).ToList();
                            break;
                        default:
                            break;
                    }
                    break;
                default:
                    users = users.OrderBy(x => x.UserEmail).ToList();
                        break;
            }
                    return View();
        }
    }

查看

<table class="table">
    <tr>
        <th>
            @Html.ActionLink("UserEmail", "Index", new { SortOrder = (ViewBag.SortOrder == null ? "Asc" : (ViewBag.SortOrder == "Asc" ? "Desc" : "Asc")), SortBy = "UserEmail", page = (ViewBag.Page == null ? "1" : ViewBag.Page) })
        </th>
        <th>
            @Html.ActionLink("Role", "Index", new { SortOrder = (ViewBag.SortOrder == null ? "Asc" : (ViewBag.SortOrder == "Asc" ? "Desc" : "Asc")), SortBy = "Role", page = (ViewBag.Page == null ? "1" : ViewBag.Page) })
        </th>

        <th></th>
    </tr>

@foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.UserEmail)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.Role)
        </td>
    </tr>
}

有人可以帮我解决这个问题吗？

Answer 1

您的视图需要模型

 @foreach (var item in Model) {

但是你没有从控制器传递模型：

 return View();

请改为尝试：

 return View(users);

在ASP.net MVC中分页空错误为什么？

1 个答案: