无法将值从视图发送到控制器

Question

我无法从视图向控制器发送值怎么办？

这是我的剃刀页面代码：

    @using (Html.BeginForm())
    {
      @for (int i = 0; i < Model.Reward.Count; i++)
      {
       @Html.EditorFor(model => Model.Reward[i].Price, new { Pric = Model.Reward[i].Price})
       @Html.HiddenFor(model => Model.Reward[i].ProductCode, new { id = Model.Reward[i].ProductCode})
       <br />
      }
    <input type="submit" value="Save" />
    }

这是控制器部分：

    [HttpPost]
    public IActionResult Index(int? id, int? Pric)
    {
        if (ModelState.IsValid)
        {
              var Product = db.Reward.ToList();
              foreach (var i in Product)
                 {
                   var rew = db.Reward.Where(x => x.ProductCode == id).FirstOrDefault();
                   rew.Price = Pric;
                 };
              db.SaveChanges();
        }
        return View();
    }

点击“保存”按钮后出现错误：

 System.NullReferenceException: „Object reference not set to an instance of an object.”