Chciałbym wiedzieć, jak mogę korzystać z mojego ViewModel na Create Action? Wypróbowałem kilka przykładów, które znalazłem tutaj na forum, ale żaden nie rozwiązał mojego problemu. Przez kilka dni dręczyłem mózg, ale nie wiem, co jest nie tak.

Ilekroć klikam przycisk Utwórz, pojawia się następujący błąd: Brak zdefiniowanego konstruktora bez parametrów dla tego obiektu.

@model MvcMusicStore.ViewModels.AlbumViewModel

@{
    ViewBag.Title = "Create";
}

<h2>Create</h2>

<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>

@using (Html.BeginForm()) {
    @Html.ValidationSummary(true)
    <fieldset>
        <legend>Album</legend>

        <div class="editor-label">
            @Html.LabelFor(model => model.AlbumItem.GenreId, "Genre")
        </div>
        <div class="editor-field">
            @Html.DropDownList("Genres", String.Empty)
            @Html.ValidationMessageFor(model => model.AlbumItem.GenreId)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.AlbumItem.ArtistId, "Artist")
        </div>
        <div class="editor-field">
            @Html.DropDownList("Artists", String.Empty)
            @Html.ValidationMessageFor(model => model.AlbumItem.ArtistId)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.AlbumItem.Title)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.AlbumItem.Title)
            @Html.ValidationMessageFor(model => model.AlbumItem.Title)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.AlbumItem.Price)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.AlbumItem.Price)
            @Html.ValidationMessageFor(model => model.AlbumItem.Price)
        </div>

        <div class="editor-label">
            @Html.LabelFor(model => model.AlbumItem.AlbumArtUrl)
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.AlbumItem.AlbumArtUrl)
            @Html.ValidationMessageFor(model => model.AlbumItem.AlbumArtUrl)
        </div>

        <p>
            <input type="submit" value="Create" />
        </p>
    </fieldset>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

Create.cshtml

    public class StoreManagerController : Controller
        {
            private MusicStoreDB db = new MusicStoreDB();

            //
            // GET: /StoreManager/Create

            public ActionResult Create()
            {
                var viewModel = new AlbumViewModel()
                {
                    Genres = new SelectList(db.Genres, "GenreId", "Name"),
                    Artists = new SelectList(db.Artists, "ArtistId", "Name")
                };
                return View(viewModel);
            } 

            //
            // POST: /StoreManager/Create

            [HttpPost]
            public ActionResult Create(AlbumViewModel vm)
            {
                if (ModelState.IsValid)
                {
                    db.Albums.Add(vm.AlbumItem);
                    db.SaveChanges();
                    return RedirectToAction("Index");  
                }

                vm.Genres = new SelectList(db.Genres, "GenreId", "Name", vm.AlbumItem.GenreId);
                vm.Artists = new SelectList(db.Artists, "ArtistId", "Name", vm.AlbumItem.ArtistId);
                return View(vm);
            }
}

StoreManager.cs - Fragment

public class AlbumViewModel
    {
        public AlbumViewModel()
        {
            //  nothing
        }

        public Album AlbumItem { get; set; }
        public SelectList Genres { get; set; }
        public SelectList Artists { get; set; }
    }

public class Album
    {
        public Album()
        {
            //  nothing
        }

        public virtual int AlbumId { get; set; }
        public virtual int GenreId { get; set; }
        public virtual int ArtistId { get; set; }
        public virtual string Title { get; set; }
        public virtual decimal Price { get; set; }
        public virtual string AlbumArtUrl { get; set; }
        public virtual Genre Genre { get; set; }
        public virtual Artist Artist { get; set; }
    }

public class Artist
    {
        public Artist()
        {
            // nothing
        }

        public virtual int ArtistId { get; set; }
        public virtual string Name { get; set; }
    }

public class Genre
    {
        public Genre()
        {
            // nothing
        }

        public virtual int GenreId { get; set; }
        public virtual string Name { get; set; }
        public virtual string Description { get; set; }
        public virtual List<Album> Albums { get; set; }
    }