ASP.NET MVC 页面验证失败(值无效。)

Question

我正在尝试使用具有一对多关系的 Entity Framework 创建 ASP.NET MVC 应用程序。为此，我已成功地将适当的项目列表加载到下拉控件(在创建 View 中)，但是当我单击创建按钮(在创建 View 中)页面验证失败时，验证错误消息为 The value '1' is invalid. .

错误



型号

public class Post
{
    public int Id { get; set; }
    ...
    public virtual Person Author { get; set; }
}

数据库上下文

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
    modelBuilder.Entity<Post>()
                .HasOptional(p => p.Author);
}

Controller

public ActionResult Create()
    {
        PopulateAuthorDropDownList();
        return View();
    }

    [HttpPost]
    public ActionResult Create(Post post)
    {
        if (ModelState.IsValid)
        {
            db.Posts.Add(post);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        PopulateAuthorDropDownList(post.Author);
        return View(post);
    }

    private void PopulateAuthorDropDownList(object selectedPerson = null)
    {
        var personQuery = from d in db.People
                          orderby d.Name
                          select d;
        ViewBag.Author = new SelectList(personQuery, "Id", "Name", selectedPerson);
    }

查看

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

当我检查数据库中的作者表时，有 ID 为 1 的记录，所以我猜 1 是一个有效值。我在这里想念什么？

提前致谢...

Answer 1

你没有展示 Author对象看起来像，

假设如果是这样，

public class Author
{ 
   public int Id{get;set;}
   public string Name{get;set;}
}

尝试这个，

<div class="editor-label">
    @Html.LabelFor(model => model.Author)
</div>
<div class="editor-field">
    @Html.DropDownListFor(model => model.Author.Id, ViewBag.Author, "Select an Author")
    @Html.ValidationMessageFor(model => model.Author)
</div>