Error when Search() Action Method returns Index View()

Question

I have a Search Form which goes to my Search() action method within my Home Controller. and returns View("Index")

Search() method:

        public IActionResult Search(SearchQuery FormData)
        {
            List<Flight> flights = new List<Flight>();

            flights = (from flight in _context.Flights
                       where flight.FlightDateTime.Date == FormData.PreferredFlightTime.Date
                       && flight.ArrivalAirportId == FormData.ArrivalAirportId
                       && flight.DepartureAirportId == FormData.DepartureAirportId
                       select flight).ToList();

            ViewBag.FlightSearchResults = flights;

            return View("Index");
        }

Upon the initial load of the homepage it works fine when loading my Index() method and returning the view.

        public IActionResult Index()
        {
            HomeViewModel mymodel = new HomeViewModel();
            mymodel.Airports = GetAirports();
 
            return View(mymodel);
        }

However once the search form is submitted and the Search() action method is called, when the method returns return View("Index"); the page will not load due System.NullReferenceException: 'Object reference not set to an instance of an object.'

The above exception is thrown when it reaches @foreach (Airport airport in Model.Airports)

Search form:

@using FlightBooker;
@model FlightBooker.Models.HomeViewModel;

<form asp-controller="Home" asp-action="Search" method="post">
                <div class="form-group">
                    <label for="fromAirport">Flying from:</label>
                    <select name=" {DepartureAirportId" class="form-control">
                        @foreach (Airport airport in Model.Airports)
                        {
                            <option value="@airport.AirportId">@airport.AirportCode</option>
                        }
                    </select>

                    <div class="form-group">
                        <label for="toAirport">Flying to:</label>
                        <select name="ArrivalAirportId" class="form-control">
                            @foreach (Airport airport in Model.Airports)
                            {
                                <option value="@airport.AirportId">@airport.AirportCode</option>
                            }
                        </select>
                    </div>
                    <label for="fromAirport">Departure Date:</label>
                    <br />
                    <input type="date" / id="date" name="PreferredFlightTime">
                    <br />
                    <label for="fromAirport">No. passengers:</label>
                    <select class="form-control" name="TotalPassengers">
                        <option>1</option>
                        <option>2</option>
                        <option>3</option>
                        <option>4</option>
                    </select>
                    <button type="submit" class="btn btn-primary mt-3">Search Flights</button>
                </div>
            </form>

Does this answer your question? [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — CodeCaster, Nov 16 '21 at 15:25
`return View("Index", modelWithAirports)`... You don't pass a model, yet your view expects one. — CodeCaster, Nov 16 '21 at 15:26
Make sense but when I do this `return View("Index", HomeViewModel)` the error is `HomeViewModel is a type, which is not valid in the given context` — Christian, Nov 16 '21 at 15:31
You need to repeat the code you have in `Index()` to prepare the model. — CodeCaster, Nov 16 '21 at 15:32

score 0 · Answer 1 · answered Nov 16 '21 at 15:39

Comment from Codecaster above solved this. I updated my Search() action method passing the model to the Index view and repeating the code in my index method.

Updated Search() action method:

        public IActionResult Search(SearchQuery FormData)
        {
            List<Flight> flights = new List<Flight>();

            flights = (from flight in _context.Flights
                       where flight.FlightDateTime.Date == FormData.PreferredFlightTime.Date
                       && flight.ArrivalAirportId == FormData.ArrivalAirportId
                       && flight.DepartureAirportId == FormData.DepartureAirportId
                       select flight).ToList();

            ViewBag.FlightSearchResults = flights;

            HomeViewModel mymodel = new HomeViewModel();
            mymodel.Airports = GetAirports();

            return View("Index", mymodel);
        }

Error when Search() Action Method returns Index View()

1 Answers1