Question

“Object reference not set to an instance of an object” Exception occurs with the following code

VIEW Code

<%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Hello_World_MVC.Models.ModelProperty>" %>
<asp:Content ID="aboutContent" ContentPlaceHolderID="MainContent" runat="server">.
    <%using (Html.BeginForm())
  { %>
            <%foreach (var cbName in Model.Obj)//Exception throws here NullreferenceException
              {%>
            <input id="cbID" type="checkbox" name="SelectedObject" value="<%=cbName.OptionID%>"/>   
            <%} %>
<%} %>
</asp:Content>

Control page

 public ActionResult About()
        {
            AboutModels ObjAM = new AboutModels();//model class name
            ModelProperty ObjMP = new ModelProperty();
            ObjMP.Obj = ObjAM.dbValue();
            return View();
        }

Model Page
#region ModelsDTO

  public class ModelProperty
    {
        private List<double> cbvalues = new List<double>();
            public List<double> cbValues { get; set; }
        private List<Option> obj = new List<Option>();
         public List<Option> Obj { get; set; }
    }
    #endregion

    public class AboutModels
    {
        DataClasses1DataContext dbObj = new DataClasses1DataContext();

        public List<PollOption> dbValue()
        {
            List<Option> opValue = new List<Option>();
            opValue = (from Value in dbObj.Options
                         select Value).ToList<Option>();
            return opValue;
        }
}

Please help..Thanks in advance

Answer 1

Change return View(); in AboutAction with return View(ObjMP);. Your mistake is that you forget to pass generated model to view, and it is null.