Question

我收到错误提交“对象引用未设置为对象的实例”mvc2

查看页面

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<EventListing.Models.EventInfo>" %>
<%= Html.DropDownListFor(model =>  model.SelectedTimeZone, Model.TimeZones, "Select Timezone") %>

控制器

 [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Create(EventInfo EventInfo)
        {
            try
            {
                if (ModelState.IsValid)
                {
                    EventModel.Create(EventInfo);
                    return RedirectToAction("Index");
                }
                return View(); 
            }
            catch
            {
                return View();
            }
        }

模型

public SelectList TimeZones { get; set; }
private string selectedTimeZone = "";
        public string SelectedTimeZone
        {
            get { return selectedTimeZone; }
            set { selectedTimeZone = value; }
        }

public static IList<KeyValuePair<string, string>> getTIMEZOMES
        {
            get
            {
                Dbhelper DbHelper = new Dbhelper();
                IList<KeyValuePair<String, String>> Timezone = new List<KeyValuePair<String, String>>();
                DbCommand cmd = DbHelper.GetSqlStringCommond("SELECT * FROM TMP_TIMEZONES");
                DbDataReader Datareader = DbHelper.ExecuteReader(cmd);
                while (Datareader.Read())
                {
                    Timezone.Add(new KeyValuePair<String, String>(Datareader["ABBR"].ToString(), Datareader["NAME"].ToString()));
                }

                return Timezone;
            }
        }

Plz给我解决方案。

Answer 1

您需要重新填充Create操作的[HttpPost]部分中的下拉列表数据，就像我猜测您正在执行Create操作的GET版本一样。当您在HttpPost操作中执行return View(Model)时，它会直接返回该HTML视图，并且它也需要所有支持数据，就像在GET中一样！

 [AcceptVerbs(HttpVerbs.Post)]
        public ActionResult Create(EventInfo EventInfo)
        {
            try
            {
                if (ModelState.IsValid)
                {
                    EventModel.Create(EventInfo);
                    return RedirectToAction("Index");
                }
                // MISSING model in below call plus likely viewdata/viewbag for dropdownlist
                // why are you returning same view as returned when error? normally this is a RedirectToAction("DisplayEvent") or similar!
                return View(EventInfo); 
            }
            catch
            {
                // MISSING model in below call plus likely viewdata/viewbag for dropdownlist
                return View(EventInfo);
            }
        }

所以至少有两个错误：

保存成功时，为什么要返回相同的视图，就像保存失败一样？
当保存失败时，需要将EventInfo传递给视图（如果DropDownList需要，则填充viewdata / viewbag）

我有一个错误提交“对象引用未设置为对象的实例”mvc2

1 个答案: