c# - Asp MVC 下拉列表选定值未选定

Question

我有以下下拉列表，但所选值似乎不起作用。它默认为列表中的第一项。

    private List<string> GetTransmissions()
    {
        List<string> Transmission = new List<string>();
        Transmission.Add("Automatic");
        Transmission.Add("Manual");


        return Transmission;
    }

     Car car = _repository.GetCarDetails(id);

     ViewBag.Transmission = new SelectList(GetTransmissions(), car.Transmission);

在我看来我有:

    @Html.DropDownList("Transmission", (IEnumerable<SelectListItem>)ViewBag.Transmission, "Please Select", new { @class = "form-control" })

Answer 1

您需要区分保存列表的属性和保存所选值的属性。

我建议像这样为 View 使用 View 模型:

public class CarViewModel
{

    public SelectList Transmissions
    {
        get
        {
            return new SelectList(new List<SelectListItem>{
                new SelectListItem {  Value = "Manual"},
                new SelectListItem {  Value = "Automatic"}
            });                
        }
    }

    public string Transmission { get; set; }

}

并使用this DropDownListFor 版本

 @Html.DropDownListFor(model => model.Transmission,
    @Model.Transmissions, "Please Select", new { @class = "form-control" })