Question

I Got an error While submit “Object reference not set to an instance of an object” mvc2

View page

<%@ 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") %>

Controller

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

Model

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 give me the solution.

Answer 1

You need to repopulate the data for the dropdown in the [HttpPost] parts of the Create action just like I’m guessing you are doing in the GET version of your Create action. When you do a return View(Model) in the HttpPost action it literally returns that HTML view and it needs all the supporting data too just like in the GET!

 [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);
            }
        }

So at least two errors:

1. When save succeeds why are you returning same view as if save fails?
2. When save fails, need to pass in the EventInfo to the view (and populate viewdata/viewbag if needed for DropDownList)