获取 DropDownList 的选定值.ASP.NET MVC [英] Get the selected value of a DropDownList. Asp.NET MVC

问题描述

我正在尝试填充 DropDownList 并在提交表单时获取所选值:

I'm trying to populate a DropDownList and to get the selected value when I submit the form:

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; }
}

我的控制器:

    [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>
}

单击时，Action 中的参数book"始终为空.我做错了什么?

When I click, the parameter 'book' in the Action is always null. What am I doing wrong?

推荐答案

在 HTML 中，下拉框仅发送简单的标量值.在您的情况下，这将是所选书籍的 ID:

In HTML a dropdown box sends only simple scalar values. In your case that would be the id of the selected book:

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

然后调整您的控制器操作，以便您从传递给您的控制器操作的 id 中检索图书:

and then adapt your controller action so that you will retrieve the book from the id that gets passed to your controller action:

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

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