Question

I have a Controller action the receives 2 URL parameters, which are foreign keys for the data model:

 public ActionResult Create(SurveyResponseModel surveyresponsemodel, int MemberId, int ProgramId)
        {
            surveyresponsemodel.MemberId = MemberId;
            surveyresponsemodel.ProgramId = ProgramId;
            return View(surveyresponsemodel);
        } 

Here is the data model:

public class SurveyResponseModel
    {
        [Key]
        public int ResponseId { get; set; }

        public int MemberId { get; set; }

        public int ProgramId { get; set; }

        // "If yes, what changes did you make? Mark all that apply."

        [DisplayName("Did you make any changes in your practice, research, or administration activities as a result of participating in this CME activity?")]
        public string CmeChanges { get; set; }

        [DisplayName("Better patient follow-up")]
        public bool PatientFollowUp { get; set; }

        public virtual SurveyProgramModel SurveyProgramModel { get; set; }

        public virtual PersonModel PersonModel { get; set; }

And the Data Model for “SurveyProgramType”

 public class SurveyProgramModel
    {

        [Key]
        public int ProgramId { get; set; }

        public int ProgramYear { get; set; }

        public int ProgramStatusId { get; set; }

        public string ProgramTitle { get; set; }

        public int ProgramTypeId { get; set; }

        public virtual SurveyProgramTypeModel ProgramType { get; set; }

        public virtual ProgramStatusModel ProgramStatusModel { get; set; }


    }

What I want to be able to do in my view, is retrieve the ProgramTitle by the URL parameter that is passed for ProgramId. So the view looks something like:

<div class="editor-label">
            @Model.SurveyProgramModel.ProgramTitle
        </div>

However, @Model.SurveyProgramModel.ProgramTitle is throwing an exception because it is null. I’m thinking I have my navigation property set up incorrectly. Any idea what that is?

Answer 1

Shouldn’t you return your view model to the view?

public ActionResult Create(
    SurveyResponseModel surveyresponsemodel) //, int MemberId, int ProgramId)
{
    // MemberId and ProgramId arguments do not need to be defined
    // They will be picked up my MVC model binder, since there are properties
    // with the same name in SurveyResponseModel class
    //surveyresponsemodel.MemberId = MemberId;
    //surveyresponsemodel.ProgramId = ProgramId;
    surveyresponsemodel.SurveyProgramModel = new SurveyProgramModel(); // new line
    return View(surveyresponsemodel); // <- return your view model here
}