C# 获取 DropDownList 的选定值。ASP.NET MVC
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Get the selected value of a DropDownList. Asp.NET MVC
提问by Azzedine Hassaini
I'm trying to populate a DropDownList and to get the selected value when I submit the form:
我正在尝试填充 DropDownList 并在提交表单时获取所选值：
Here is my model :
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; }
}
My Controllers :
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();
}
My Form :
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>
}
When I click, the parameter 'book' in the Action is always null. What am I doing wrong?
当我单击时，Action 中的参数“book”始终为空。我究竟做错了什么？
采纳答案by Darin Dimitrov
In HTML a dropdown box sends only simple scalar values. In your case that would be the id of the selected book:
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：
@Html.DropDownList("selectedBookId", (SelectList)ViewBag.Books)
and then adapt your controller action so that you will retrieve the book from the id that gets passed to your controller action:
然后调整您的控制器操作，以便您从传递给控制器操作的 id 中检索书：
[Authorize]
[HttpPost]
public ActionResult Action(string selectedBookId)
{
if (ValidateFields()
{
Book book = FetchYourBookFromTheId(selectedBookId);
var data = GetDatasAboutBookSelected(book);
ViewBag.Data = data;
return View();
}
return View();
}
回答by mesut
You can use DropDownListFor as below, It so simpler
你可以使用 DropDownListFor 如下，它更简单
@Html.DropDownListFor(m => m.Id, new SelectList(Model.Books,"Id","Name","1"))
(You need a strongly typed view for this -- View bag is not suitable for large lists)
（为此您需要一个强类型视图——视图包不适合大列表）
public ActionResult Action(Book model)
{
if (ValidateFields()
{
var Id = model.Id;
...
I think this is simpler to use.
我认为这更易于使用。
