模型 ID 在传递给 HttpPost 方法时发生变化

Question

我正在重构 MvcMusicStore 代码，并且正在更新 StoreManagerController。我已将编辑操作更改为以下内容：

    //
    // GET: /StoreManager/Edit/5

    public ActionResult Edit(int id)
    {
        Toy toy = dbStore.Toys.Find(id);
        ViewBag.CategoryId = new SelectList(dbStore.Categories, "CategoryId", "Name", toy.CategoryId);
        ViewBag.BrandId = new SelectList(dbStore.Brands, "BrandId", "Name", toy.BrandId);
        return View(toy);
    }

    //
    // POST: /StoreManager/Edit/5

    [HttpPost]
    public ActionResult Edit(Toy toy)
    {
        if (ModelState.IsValid)
        {
            dbStore.Entry(toy).State = EntityState.Modified;
            dbStore.SaveChanges();
            return RedirectToAction("Index");
        }
        ViewBag.CategoryId = new SelectList(dbStore.Categories, "CategoryId", "Name", toy.CategoryId);
        ViewBag.BrandId = new SelectList(dbStore.Brands, "BrandId", "Name", toy.BrandId);
        return View(toy);
    }

在测试时，当我单击Edit 操作时，视图显示正常，在Edit(int id) 方法中设置断点显示ToyId 为1。但是，在我进行更改并单击保存后，通过方法ActionResult Edit(Toy toy) 传递的Toy 对象有不正确的ToyId 等于0。

此修改发生在哪里，或者是否有 toy 的副本从视图传回并且它没有正确地复制到 ToyId 中？

更新：添加了编辑视图的帖子

@model Store.Models.Toy

@{
    ViewBag.Title = "Edit";
}

<h2>Edit</h2>

<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript">      </script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")"   type="text/javascript"></script>

@using (Html.BeginForm()) {
@Html.ValidationSummary(true)
<fieldset>
    <legend>Toy</legend>

    @Html.HiddenFor(model => model.ToyId)

    <div class="editor-label">
        @Html.LabelFor(model => model.CategoryId, "Category")
    </div>
    <div class="editor-field">
        @Html.DropDownList("CategoryId", String.Empty)
        @Html.ValidationMessageFor(model => model.CategoryId)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.BrandId, "Brand")
    </div>
    <div class="editor-field">
        @Html.DropDownList("BrandId", String.Empty)
        @Html.ValidationMessageFor(model => model.BrandId)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.Title)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.Title)
        @Html.ValidationMessageFor(model => model.Title)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.Price)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.Price)
        @Html.ValidationMessageFor(model => model.Price)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.PictureUrl)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.PictureUrl)
        @Html.ValidationMessageFor(model => model.PictureUrl)
    </div>

    <p>
        <input type="submit" value="Save" />
    </p>
</fieldset>
}

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

玩具课

[Bind(Exclude = "ToyId")]
public class Toy
{
    [ScaffoldColumn(false)]
    public int ToyId { get; set; }

    // ... other stuff here
}

Answer 1

因为

[Bind(Exclude = "ToyId")] 

所以 ToyID 属性在绑定操作中实际上被忽略了，隐藏的值没有被使用。

您可以简单地从类中删除它，以便ToyId 从 POST 操作中正确绑定；或者，您可以通过将id 路由值复制到Toy 的ToyId 属性，在控制器方法中手动绑定它（或添加一个名为id 的方法参数使其自动绑定）。

但是，允许绑定 ID 属性等存在一些潜在问题，而另一个 SO 提供了一个窗口：ASP.NET MVC - Alternative for [Bind(Exclude = "Id")]