Question 336622 in ASP.NET Question posted in
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Asp.net – FirstOrDefault returns foreign key as null always

I’m building a web app using Entity Framework Core.

I have a view model with a property:

Public IEnumerable<AppointmentDTO> Appointments

Appointment has a foreign key DoctorId.

Now in the view where Im using the view model, I have:

@foreach (var doc in Model.Doctors)
{
    var appointment = Model.Appointments?.FirstOrDefault(a => a.DoctorId == doc.Id);
}

The issue is all DoctorId are returned as null, for all appointments, even though it’s not.

Does anybody know what the issue could be?

Appointment model

public int? DoctorId { get; set; }
public Doctor Doctor { get; set; }

Doctor model

public List<Appointment>? Appointments { get; set; }

I thought it could be because doctorId is nullable, so I made it required, but that didn’t work, either.

Tags:

2

Answers


  1. 0

    public class AppointmentDTO {
    public int? DocId { get; set; }

      public Doctor Doctor { get; set; }

    viewModel:

    public class CalendarViewModel
    {
    public IEnumerable? Doctors { get; set; }

        public IEnumerable<AppointmentDTO>? Appointments { get; set; }

    view:

    @model ClinicaApp.ViewModels.CalendarViewModel

    @{
    var selectedSections = ViewData["SelectedSections"] as List; }

    <div class="paging">
    <a href="#" class="previous" onclick="updateDate(-1)" id="arrow">&laquo; Previous</a>
    <input class="date" type="text" value="" id="flexCheckDefault">

    <a href="#" class="next" onclick="updateDate(1)" id="arrow">Next &raquo;</a>
</div>


@if (Model.Doctors != null)
{
    @foreach (var doc in Model.Doctors)
    {
        // var appointment = Model.Appointments?.FirstOrDefault( a => a.DoctorId ==1 );
        var appointment = Model.Appointments?.FirstOrDefault(a => a.DoctorId == 1);
        if (appointment != null)
            Console.WriteLine("true");
    }
}
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  2. 0

    Make sure in the controller you have define the view model , set the list Doctors and Appointments value.

    like:

     public IActionResult Index()
 {
     var doctors= _context.Doctors.ToList();
     var appointments= _context.Appointments.ToList();//you can set the data as your way
     var model = new yourViewModel();
     model.Doctors = doctors;
     model.Appointments = appointments;   
     return View(model);
 }
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