c# - 获取 DropDownList 的选定值。 ASP.NET MVC

Question

我正在尝试填充 DropDownList 并在提交表单时获取选定的值:

这是我的模型:

public class Book
{
    public Book()
    {
        this.Clients = new List<Client>();
    }

    public int Id { get; set; }
    public string JId { get; set; }
    public string Name { get; set; }
    public string CompanyId { get; set; }
    public virtual Company Company { get; set; }
    public virtual ICollection<Client> Clients { get; set; }
}

我的 Controller :

    [Authorize]
    public ActionResult Action()
    {
        var books = GetBooks();
        ViewBag.Books = new SelectList(books);
        return View();
    }

    [Authorize]
    [HttpPost]
    public ActionResult Action(Book book)
    {
        if (ValidateFields()
        {
            var data = GetDatasAboutBookSelected(book);
            ViewBag.Data = data;
            return View();
        }
        return View();
    }

我的表格:

@using (Html.BeginForm("Journaux","Company"))
{
<table>
    <tr>
        <td>
            @Html.DropDownList("book", (SelectList)ViewBag.Books)
        </td>
    </tr>
    <tr>
        <td>
            <input type="submit" value="Search">
        </td>
    </tr>
</table>
}

当我点击时，Action 中的参数“book”始终为空。 我做错了什么？

Answer 1

在 HTML 中，下拉框仅发送简单的标量值。在您的情况下，这将是所选图书的 ID:

@Html.DropDownList("selectedBookId", (SelectList)ViewBag.Books)

然后调整您的 Controller 操作，以便您可以从传递给您的 Controller 操作的 id 中检索图书:

[Authorize]
[HttpPost]
public ActionResult Action(string selectedBookId)
{
    if (ValidateFields()
    {
        Book book = FetchYourBookFromTheId(selectedBookId);
        var data = GetDatasAboutBookSelected(book);
        ViewBag.Data = data;
        return View();
    }
    return View();
}