如何在.NET MVC3 HTML表单中允许所需的可为空的DateTime中使用null值？

public class MyModel
{
    public DateTime? MyNullableDateTime { get; set; }
}

@model MyModel

@using (Html.BeginForm())
{
    @Html.TextBoxFor(m => m.MyNullableDateTime)
    <input type="submit" value="Submit" />
}

[HttpPost]
public ActionResult MyAction(MyModel model)
{
    DateTime? myNullableDateTime = null;
    if (!string.IsNullOrEmpty(Request.Form["MyNullableDateTime"]))
    {
        DateTime tempDateTime;
        if (DateTime.TryParse(Request.Form["MyNullableDateTime"], out tempDateTime))
        {
            myNullableDateTime = tempDateTime;
        }
        else
        {
            // 处理日期格式不正确的情况
        }
    }

    model.MyNullableDateTime = myNullableDateTime;

    // 其他处理逻辑

    return View(model);
}