asp .net核心mvc下拉列表的选定值

<!-- 视图文件 -->
<form method="post" asp-action="SubmitForm">
    <select name="Gender">
        <option value="Male">Male</option>
        <option value="Female">Female</option>
        <option value="Other">Other</option>
    </select>
    <button type="submit">Submit</button>
</form>

public class UserViewModel
{
    public string Gender { get; set; }
    public List<SelectListItem> Genders { get; set; }
}

public class HomeController : Controller
{
    public IActionResult Index()
    {
        var model = new UserViewModel
        {
            Genders = new List<SelectListItem>
            {
                new SelectListItem { Value = "Male", Text = "Male" },
                new SelectListItem { Value = "Female", Text = "Female" },
                new SelectListItem { Value = "Other", Text = "Other" }
            }
        };
        return View(model);
    }

    [HttpPost]
    public IActionResult SubmitForm(UserViewModel model)
    {
        // 处理表单提交
        return RedirectToAction("Index");
    }
}

<!-- 视图文件 -->
<form method="post" asp-action="SubmitForm">
    <select asp-for="Gender" asp-items="Model.Genders">
    </select>
    <button type="submit">Submit</button>
</form>

<select asp-for="Gender" asp-items="Model.Genders">
</select>

public IActionResult Index()
{
    var model = new UserViewModel
    {
        Genders = new List<SelectListItem>
        {
            new SelectListItem { Value = "Male", Text = "Male" },
            new SelectListItem { Value = "Female", Text = "Female" },
            new SelectListItem { Value = "Other", Text = "Other" }
        }
    };
    return View(model);
}