I've been struggling with this error for a few days now for an assignment and I can't get it fixed, I've shown it to another person and we are bewildered as to what could be the issue? "InvalidOperationException: The model item passed into the ViewDataDictionary is of type 'FYP_RSVP_MGMT.Models.GuestList', but this ViewDataDictionary instance requires a model item of type 'FYP_RSVP_MGMT.ViewModels.GuestListViewModel'."

GuestListController:

public class GuestListController : Controller
{
    public IActionResult Index()
    {
        GuestListViewModel guest = new GuestListViewModel();

        return View("Index", guest);
    }

    public IActionResult CreateUpdate(GuestListViewModel guest)
    {
        if(ModelState.IsValid)
        {
            using (var db = DbHelpers.GetConnection()) {

                if(guest.EditableGuest.GuestID == null)
                {
                    /* Count the existing IDs and adds the next ID */
                    guest.EditableGuest.GuestID = guest.Guests.Count;

                    db.Insert<GuestList>(guest.EditableGuest);
                }

                /* If the guest already exists, we are updating the details*/
                else
                {
                    GuestList dbItem = db.Get<GuestList>(guest.EditableGuest.GuestID);

                    TryUpdateModelAsync<GuestList>(dbItem, "EditableGuest");

                    db.Update<GuestList>(dbItem);
                }
            }

            return RedirectToAction("ViewGuestList");
        }

        else
        {
            return View("Index", new GuestList());
        }
       
    }

GuestListViewModel

public class GuestListViewModel
{
    public GuestListViewModel()
    {
        using (var db = DbHelpers.GetConnection())
        {
            this.EditableGuest = new GuestList();

            this.Guests = db.Query<GuestList>("Select * From GuestList").ToList();
        }
    }

    public List <GuestList> Guests { get; set; }

    /* Holds any instance of an object that is being added/edited/deleted etc */
    public GuestList EditableGuest { get; set; }


}

GuestList Model

 public class GuestList
{
    public int? GuestID { get; set; }

    [Required]
    public string GuestName { get; set; }

    [Required]
    public string GuestType { get; set; }

    [Required]
    public string ContactDetails { get; set; }

    public bool PlusOne { get; set; }

    public string PlusOneName { get; set; }

    [Required]
    public string Response { get; set; }
}

Index.cshtml - where form is being displayed

@model FYP_RSVP_MGMT.ViewModels.GuestListViewModel

@{
ViewData["Title"] = "Guest RSVP";
 }

    @using (var form = Html.BeginForm("CreateUpdate", "GuestList", FormMethod.Post))
    {
<div class="container" id="GuestRSVP">

    <br/>
    <br/>
    <br/>

    <h3> Welcome to [Bride] and [Groom]s Wedding</h3>
    <h4>[Church Location]</h4>
    <h4>[Wedding Date and Time]</h4>

    <div class="container"  id="RSVPTable" style="align-content:center">

        <table>

            

            <tr>
                <td>Guest Name: </td>
                <td>@Html.TextBoxFor(m => m.EditableGuest.GuestName)</td>
                <td>@Html.HiddenFor(m => m.EditableGuest.GuestID)</td>
            </tr>

            <tr>
                <td>Guest Type: </td>
                <td>@Html.DropDownListFor(m => m.EditableGuest.GuestType, new List<SelectListItem> { new SelectListItem { Value = "Guest", Text = "Guest" }, new SelectListItem { Value = "Wedding Party", Text = "Wedding Party" } })</td>
            </tr>

            <tr>
                <td>Contact Details: </td>
                <td>@Html.TextBoxFor(m => m.EditableGuest.ContactDetails)</td>
            </tr>

            <tr>
                <td>Plus One: </td>
                <td>@Html.CheckBoxFor(m => m.EditableGuest.PlusOne)</td>
            </tr>

            <tr>
                <td>Plus One Name: </td>
                <td>@Html.TextBoxFor(m => m.EditableGuest.PlusOneName)</td>
            </tr>

            <tr>
                <td>RSVP Response:</td>
                <td>@Html.DropDownListFor(m => m.EditableGuest.Response, new List<SelectListItem> { new SelectListItem { Value = "Accept with Pleasure", Text = "Accept with Pleasure" }, new SelectListItem { Value = "Decline with Regret", Text = "Decline with Regret" } })</td>
            </tr>


            <tr>
                <td><button class="btnSubmitRSVP" type="submit"> @(Model.EditableGuest.GuestID > 0? "Update": "Add") </button></td>
                <td></td>
            </tr>

        </table>


    </div>


</div>

}

We cannot figure out why the model is being passed and not the viewmodel? My code doesn't refer to the model? Any help would be much appreciated!

CodePudding user response：

I'd say it's coming from here:

You're sending a GuestList in the else despite promising you'd send a GuestListViewModel at the top of the page: