c# - MVC 4 Entity Framework 模型为空

Question

每次运行时，我的卡车 Controller 中都有这段代码。

我的模型总是空的。

    [HttpPost]
    public ActionResult AddTruck(TruckDataModel model)
    {
        var newTruck = new truck()
        {
            registration_no = model.reg_no,
            make = model.make,
            model = model.model,
            engine_no = model.engine_no,
            chassis_no = model.chassis_no,
            driver_name = model.driver_name,
            driver_no = model.driver_no,
            current_run = model.current_run,

        };

        if (ModelState.IsValid)
        {
            db.trucks.Add(newTruck);
            db.SaveChanges();
            return RedirectToAction("TruckList","Trucks");
        }

        return View(model);

这是我的模型

public class TruckDataModel
{         
    [Required(ErrorMessage = "Registration No. required", AllowEmptyStrings = false)]
    [Display(Name = "Registration No.")]
    public string reg_no { get; set; }

    [Required(ErrorMessage = "Make required", AllowEmptyStrings = false)]
    [Display(Name = "Make")]
    public string make { get; set; }

    [Required(ErrorMessage = "Model required", AllowEmptyStrings = false)]
    [Display(Name = "Model")]
    public string model { get; set; }

    [Required(ErrorMessage = "Engine No. required", AllowEmptyStrings = false)]
    [Display(Name = "Engine No.")]
    public string engine_no { get; set; }

    [Required(ErrorMessage = "Chassis No. required", AllowEmptyStrings = false)]
    [Display(Name = "Chassis No.")]
    public string chassis_no { get; set; }

    [Required(ErrorMessage = "Driver Name required", AllowEmptyStrings = false)]
    [Display(Name = "Driver Name")]
    public string driver_name { get; set; }

    [Required(ErrorMessage = "Current Run required", AllowEmptyStrings = false)]
    [Display(Name = "Current Run")]
    public int current_run { get; set; }

    [Required(ErrorMessage = "Driver no. required", AllowEmptyStrings = false)]
    [Display(Name = "Driver No.")]
    public int driver_no { get; set; }


}//just for allow to edit

我总是会出现 NullReference 异常，当我设置断点时，所有模型都为空。

我的 CreateUser 操作中有准确的代码，但它工作得很好吗？ 非常需要帮助!

Answer 1

您的 TruckDataModel 模型有一个名为 model 的属性，您的 POST 方法参数也名为 model。你需要改变一个或另一个，比如说

public ActionResult AddTruck(TruckDataModel truck)
{
  ....
}

原因是 DefautModelBinder 首先初始化了一个 TruckDataModel 的实例。然后它读取表单数据，看到 model 的名称/值对，然后尝试将您的参数设置为其值(比如 model="Ford")，但失败了因此模型变为 null