Question

我想在实体模型中编辑ASP MVC中的数据。但是，在发送表单时，我的控制器会收到空值（控制器中的错误）。我不知道为什么会这样。我是MVC的新手。

System.NullReferenceException: 'Object reference not set to an instance of an 
object.'
getmenu was null.

我不明白为什么它有空值。谁能详细说明？

模型

namespace Shop
{
    using System;
    using System.Collections.Generic;

    public partial class menu
    {
        public int id { get; set; }
        public string name { get; set; }
        public string type { get; set; }
        public Nullable<double> price { get; set; }
    }
    }

查看

@model Shop.menu

@{
    ViewBag.Title = "edit";
}

<h2>edit</h2>


@using (Html.BeginForm())
{
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>menu</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        @Html.HiddenFor(model => model.id)

        <div class="form-group">
            @Html.LabelFor(model => model.name, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.name, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.name, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.type, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.type, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.type, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.price, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.price, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.price, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </div>
    </div>
}

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

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

控制器

namespace Shop.Controllers
{
    public class HomeController : Controller
    {
        shopcontext db = new shopcontext();

 public ActionResult edit()
        {

            return View();
        }

        [HttpPost]
        public ActionResult edit(menu menu)
        {

            var getmenu = db.menus.Where(p => p.id == menu.id).FirstOrDefault();
            getmenu.name = menu.name;
            getmenu.type = menu.type;
            getmenu.price = menu.price;
            db.SaveChanges();
            return RedirectToAction("Index");

        }
}
}

这些都是代码。请让我知道你的想法！

Answer 1

替换

@using (Html.BeginForm())

通过

@using (Html.BeginForm("edit", "Home", FormMethod.Post))

2

[HttpGet]
public ActionResult edit()
{
   var model= new Shop.menu();
    return View(model);
}

3

[HttpPost]
 [ValidateAntiForgeryToken]
public ActionResult edit(menu menu)
{
    //........
}

编辑ASP MVC空值

1 个答案: