object reference not set in combobox with two model view razor

Question

I tried to create more than one combobox, but model to view combobox is different. then I tried to combine two models in one class, but I get an error "object reference not set to an instance of an object" when I click on the link to go to that page. please help me to fix the matter. thank you, sorry if I mess sentence. This piece from some source code : controller partial combobox ,

 [ValidateInput(false)]
    public ActionResult cbPartialCategoryDetail(string group)
    {
        SalesMonitoringDAC modelSM = new SalesMonitoringDAC();
        MPMPRODUCTGROUPLINE item = new MPMPRODUCTGROUPLINE();
        item.GROUPID = group;
        List<string> mpmDetailCat = modelSM.GetProductGroupDetail(group);

        return PartialView("_cbPartialCategoryDetail", mpmDetailCat);
    }

and this is code combobox partial

    @model  DIS_iDealer.Models.SalesMonitoringModel

@Html.DevExpress().ComboBoxFor(m => m.mpmGroupLine.DESCRIPTION, settings =>
{
    settings.Name = "Desc_ID_CB";
    settings.Properties.IncrementalFilteringMode = IncrementalFilteringMode.Contains;
    settings.Properties.DropDownStyle = DropDownStyle.DropDownList;
    settings.CallbackRouteValues = new { Controller = "Report", Action = "cbPartialCategoryDetail" };
    settings.Properties.CallbackPageSize = 50;
    settings.Properties.ValueField = "DESCRIPTION";
    settings.Properties.TextField = "DESCRIPTION";
    settings.Properties.ValueType = typeof(string);

    settings.Width = 100;
    settings.Properties.DropDownWidth = 100;
    settings.SelectedIndex = 0;

    settings.Properties.ClientSideEvents.BeginCallback = "function(s, e) { e.customArgs['GroupId'] = Category_Id_CB.GetValue(); }";
    settings.Properties.ClientSideEvents.SelectedIndexChanged = "OnInitDetailCategory";
    settings.Properties.ClientSideEvents.Init = "OnInisialDetailCategory";

    settings.Properties.ValidationSettings.ErrorTextPosition = ErrorTextPosition.Right;
    settings.Properties.ValidationSettings.ErrorDisplayMode = ErrorDisplayMode.ImageWithText;
    settings.Properties.ValidationSettings.Display = Display.Dynamic;
    settings.Enabled = true;
    settings.ShowModelErrors = true;    

//}).BindList(ViewBag.DetailCategory).GetHtml()
}).BindList((new DIS_iDealer.DataAccess.SalesMonitoringDAC()).GetProductGroupDetail(Model.mpmGroupLine.GROUPID)).GetHtml()

this is class two combine the two model

    namespace DIS_iDealer.Models
{
    public class SalesMonitoringModel
    {
        public MPMPRODUCTGROUPLINE mpmGroupLine { get; set; }
        public MPMDataDealer mpmDataDealer { get; set; }

        public SalesMonitoringModel(MPMPRODUCTGROUPLINE _mpmGroupLine, MPMDataDealer _mpmDataDealer) {
            mpmGroupLine = _mpmGroupLine;
            mpmDataDealer = _mpmDataDealer;
        }
    }   
}

Rahul Rahul · Accepted Answer · 2016-01-20T03:58:57

Isn't that really strange. In your action method you are returning a List<string> as seen below

List<string> mpmDetailCat = modelSM.GetProductGroupDetail(group);
return PartialView("_cbPartialCategoryDetail", mpmDetailCat);

Whereas in your partial view you are expecting a model of type SalesMonitoringModel and that's the source of this error. I am not sure what you are exactly trying to achieve and so can't help beyond this

@model  DIS_iDealer.Models.SalesMonitoringModel

object reference not set in combobox with two model view razor

1 Answers