MVC Html.DropDownListFor 返回具有空值的复杂类型

Question

我的控制器中有以下控制器创建操作。请注意选择列表中的显示名称将是“StoreName - StoreAddress”。 Store complexType 存储在 Store 中。

        // GET: Purchases/Create
        public ActionResult Create()
        {
            ViewBag.Stores = db.Stores.Select(s => new { DisplayName = s.StoreName.ToString() + " - " + s.Address.ToString(), Store = s});

            return View();
        }

在创建视图中，以下代码会确保正确显示。

    <div class="form-group">
        @Html.LabelFor(model => model.Store.StoreName, htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.Store.StoreName, new SelectList(ViewBag.Stores, "Store", "DisplayName"), new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.Store.StoreName, "", new { @class = "text-danger" })
        </div>
    </div>

它将转到控制器的 post 方法（如果我是正确的）。

        // POST: Purchases/Create
        // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
        // more details see https://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create([Bind(Include = "Id,Store,Price,Date")] Purchase purchase)
        {
            if (ModelState.IsValid)
            {
                Store store = purchase.Store;

                db.Purchases.Add(purchase);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            return View(purchase);
        }

不过，Store store = purchase.Store 现在将给出一个复杂的 Store 类型，其中除 StoreName 之外的任何值都设置为 null。 StoreName 将是一个字符串。

如何获得与所选 Store 对象相等的复杂类型返回？

---

编辑1：

public class Purchase
   {
       public int Id { get; set; }

       public Store Store { get; set; }

       public string Type { get; set; }

       [DataType(DataType.Currency)]
       [Column(TypeName = "money")]
       public decimal Price { get; set; }

       [DataType(DataType.Date)]
       [DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}", ApplyFormatInEditMode = true)]
       public DateTime Date { get; set; }
   }

public class PurchaseDBContext : DbContext
   {
       public DbSet<Purchase> Purchases { get; set; }
       public DbSet<Store> Stores { get; set; }

       protected override void OnModelCreating(DbModelBuilder modelBuilder)
       {

       }
   }

public class Store
    {
        public int StoreId { get; set; }

        public string StoreName { get; set; }

        public string Address { get; set; }

        public string City { get; set; }

        [DataType(DataType.PhoneNumber)]
        [RegularExpression(@"^((\+|00(\s|\s?\-\s?)?)31(\s|\s?\-\s?)?(\(0\)[\-\s]?)?|0)[1-9]((\s|\s?\-\s?)?[0-9])((\s|\s?-\s?)?[0-9])((\s|\s?-\s?)?[0-9])\s?[0-9]\s?[0-9]\s?[0-9]\s?[0-9]\s?[0-9]$", ErrorMessage = "This is not a valid phonenumber")]
        public string PhoneNumber { get; set; }

    }

是否需要使用额外的注解来设置导航属性？

Answer 1

您的示例中有很多内容，但如果您使用导航属性并且您的模型以某种方式设置，则无需传递复杂的对象。如果您为 Store/StoreId 设置导航属性，Entity Framework 应该为您推断事物，因此它将简化您的视图。

public class Purchase 
{
    public int StoreId { get; set; }
    [ForeignKey("StoreId")]
    public Store Store { get; set;}
}

我会将模型传递给类似于下面的视图。 IMO，它比使用 ViewBag 更干净。

public class CreatePurchaseModel
{
    //To populate a list
    public List<Store> AvailableStores { get; set; }
    //The actual object to be created
    public Purchase Purchase { get; set; }
}

控制器方法：

// GET: Purchases/Create
public ActionResult Create()
{
    var vm = new CreatePurchaseModel() 
    {
        AvailableStores = db.Stores.ToList(),
        Purchase = new Purchase()
    };

    return View(vm);     
}

使用 AvailableStores 属性填充下拉列表以设置 Purchase.StoreId

@Html.DropDownListFor(m => m.Purchase.StoreId, Model.AvailableStores.Select(x => new SelectListItem { Text = x.StoreName.ToString(), Value = x.StoreId.ToString() }))

如果设置正确，post方法参数中只需要购买

[ValidateAntiForgeryToken, HttpPost]
public ActionResult Create(Purchase purchase) 
{
    //purchase.StoreId should have a non zero value
    db.Purchases.Add(purchase);
    db.SaveChanges();
}