Question

我知道还有其他类似的问题，但我无法在任何地方找到合适的解决方案。

关键是我希望用户在dropDownList中选择日期，将该日期作为操作方法的参数，并根据所选日期显示数据库的结果。但总是在dropDownList中选择任何项后，它会向控制器返回null。

这是我的控制器的方法：

    public ActionResult Index(DateViewModel dateViewModel)
    {
        dateViewModel.Dates = GetDates();

        return View(dateViewModel);
    }

    private IEnumerable<SelectListItem> GetDates()
    {
        var dbContext = new DbContext();

        var dates = dbContext .TestResults
            .Where(result => result.CompletedOn != null)
            .OrderBy(result => result.CompletedOn)
            .Select(result => result.CompletedOn).ToList();

        var sortedDates = dates
            .GroupBy(date => date.Month)
            .Select(date => date.First())
            .Select(date => new SelectListItem { Text = date.ToString("MMMM yy"), Value = date.Month.ToString() + " " + date.Year.ToString()})
            .ToList();

         return new SelectList(sortedDates, "Value", "Text");
    }

    [HttpPost]
    public ActionResult ShowDepartmentArchive(string date)
    {
        //some logic with date here
        return PartialView(depResults);
    }

我有一个用于dropDownList的ViewModel：

public class DateViewModel
{
    [Display(Name = "Выбранная дата")]
    public string SelectedDate { get; set; }

    [Display(Name = "Выберите дату: ")]
    public IEnumerable<SelectListItem> Dates { get; set; }
}

最后，在我看来：

   @model QA.Web.App.Models.DateViewModel
       @using (Html.BeginForm("ShowDepartmentArchive", "Archive"))
       {
           @Html.Hidden("SelectedDate", Model.SelectedDate)
           @Html.DropDownListFor(m => m.SelectedDate, Model.Dates, "Выберите 
   дату", new {onchange = "this.form.submit();"})}

DropDownListFor将null返回给controller

0 个答案: