视图模型未保存在为会话绑定的“编辑HttpPost”中

Question

出于某些原因，在Controller Edit中，当我保存购物车数量时，它不保存任何内容，并在HttpPost Edit中为viewmodel返回null。我该如何解决这个问题？它适用于我所有其他具有不同模型的控制器，但是我认为Sessions不能正常工作。我的AddtoCart和RemoveFromCart函数正常工作。

shoppingCartViewModel在“编辑帖子”中为空

型号：

namespace ElectronicsStore.Models
{
    public class ShoppingCart : List<CartLine>
    {
        public ShoppingCart() { }
        public ShoppingCart(IEnumerable<CartLine> collection) : base(collection) { }
        public ShoppingCart(int capacity) : base(capacity) { }
    }
}

public class CartLine
{
    public int CartLineId { get; set; }
    public Product Product { get; set; }
    public int Quantity { get; set; }
    public float TotalDollar { get => Quantity * Product.getUnitPrice();}
}

存储库：

public class ShoppingCartRepository : IShoppingCartRepository<ShoppingCart>
{

    private ShoppingCart shoppingCart = new ShoppingCart();
    //private List<CartLine> lineCollection = new List<CartLine>();

    public ShoppingCart GetAll()
    {
        return shoppingCart;
    }

    public virtual void AddItem(Product product, int quantity)
    {
        shoppingCart.Find(p => p.Product == product);

        CartLine cartline = shoppingCart.Where(p => p.Product.ProductId == product.ProductId).FirstOrDefault();

        if (cartline == null)
        {
            shoppingCart.Add(new CartLine
            {
                Product = product,
                Quantity = quantity
            });
        }
        else
        {
            cartline.Quantity += quantity;
        }

    }

    public virtual void RemoveItem(int cartlineid)
    {
        shoppingCart.RemoveAll(l => l.CartLineId == cartlineid);
    }

    public virtual void UpdateItem(ShoppingCartViewModel shoppingcartviewmodel)
    {
        shoppingCart = shoppingcartviewmodel.ShoppingCart;
    }

    public virtual IEnumerable<CartLine> Lines => shoppingCart;
}

}

控制器：

public class ShoppingCartController : Controller
{
    private IProductRepository<Product> _productRepository;
    private ShoppingCartRepository _shoppingCartRepository;


    public ShoppingCartController(IProductRepository<Product> productRepository, ShoppingCartRepository shoppingCartRepository)
    {
        _productRepository = productRepository;
        _shoppingCartRepository = shoppingCartRepository;
    }

    public async Task<IActionResult> Edit(string returnUrl)
    {

        ShoppingCartViewModel shoppingCartViewModel = new ShoppingCartViewModel();

        shoppingCartViewModel.ShoppingCart = _shoppingCartRepository.GetAll();
        shoppingCartViewModel.ReturnUrl = returnUrl;

        return View(shoppingCartViewModel);
    }

    // POST: Products1/Edit/5
    // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
    // more details see http://go.microsoft.com/fwlink/?LinkId=317598.
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Edit(ShoppingCartViewModel shoppingCartViewModel, string returnUrl)
    {
        _shoppingCartRepository.UpdateItem(shoppingCartViewModel);
        return RedirectToAction("Edit", new { returnUrl });
    }

    public RedirectToActionResult AddToCart(int productid, string returnUrl)
    {
        Product product = _productRepository.GetById(productid);
        _shoppingCartRepository.AddItem(product, 1);

        return RedirectToAction("Edit", new { returnUrl });
    }

    public RedirectToActionResult RemoveFromCart(int cartlineid, string returnUrl)
    {
        _shoppingCartRepository.RemoveItem(cartlineid);

        return RedirectToAction("Index", new { returnUrl });
    }
}

}

查看：

@model ShoppingCartViewModel
@{
    ViewData["Title"] = "Index";
}

<h2>Shopping Cart</h2>

<h2>Edit</h2>

<h4>Product</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        @foreach (var item in Model.ShoppingCart)
        {
            <form asp-action="Edit" class="row">
                <div asp-validation-summary="ModelOnly" class="text-danger"></div>
                <input type="hidden" asp-for="@item.CartLineId" />
                <div class="form-group col-md-4">
                    <label asp-for="@item.Product.ProductName" class="control-label"></label>
                    <input asp-for="@item.Product.ProductName" class="form-control" />
                    <span asp-validation-for="@item.Product.ProductName" class="text-danger"></span>
                </div>
                <div class="form-group col-md-4">
                    <label asp-for="@item.Quantity" class="control-label"></label>
                    <input asp-for="@item.Quantity" class="form-control" />
                    <span asp-validation-for="@item.Quantity" class="text-danger"></span>
                </div>
                <div class="form-group col-md-4">
                    <input type="submit" value="Save" class="btn btn-default" />
                </div>
            </form>
        }
        </div>
</div>

<div>
    <a asp-action="Index">Back to List</a>
</div>

@section Scripts {
    @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

启动：

        services.AddTransient<ISupplyRepository<Supply>, SupplyRepository>();
        services.AddTransient<ShoppingCartRepository>(sp => ShoppingCartSession.GetCart(sp));
        services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

会话：

  public class ShoppingCartSession : ShoppingCartRepository
    {
    public static ShoppingCartRepository GetCart(IServiceProvider services)
    {
        ISession session = services.GetRequiredService<IHttpContextAccessor>()?.HttpContext.Session;
        ShoppingCartSession shoppingcartsession = session?.GetJson<ShoppingCartSession>("ShoppingCartRepository") ?? new ShoppingCartSession();
        shoppingcartsession.Session = session;
        return shoppingcartsession;
    }

    [JsonIgnore]
    public ISession Session { get; set; }

    public override void AddItem(Product product, int quantity)
    {
        base.AddItem(product, quantity);
        Session.SetJson("ShoppingCartRepository", this);
    }

    public override void RemoveItem(int cartlineid)
    {
        base.RemoveItem(cartlineid);
        Session.SetJson("ShoppingCartRepository", this);
    }

    public override void UpdateItem(ShoppingCartViewModel shoppingcartviewmodel)
    {
        base.UpdateItem(shoppingcartviewmodel);
        Session.SetJson("ShoppingCartRepository", this);
    }
}

会话扩展：

    public static void SetJson(this ISession session, string key, object value)
    {
        session.SetString(key, JsonConvert.SerializeObject(value));
    }

    public static T GetJson<T>(this ISession session, string key)
    {
        var sessionData = session.GetString(key);
        return sessionData == null
            ? default(T) : JsonConvert.DeserializeObject<T>(sessionData);
    }