创建IEnumerable DropDownList

Question

如何在ASP MVC 5中创建IEnumerable下拉列表？

我使用此功能但它显示错误：

  public ActionResult EditStudent()
    {
        ViewBag.Reshte = new SelectList(_db.Tbl_Reshte, "ReshteID", "ReshteName");
        ViewBag.Paye = new SelectList(_db.Tbl_Paye, "PayeID", "PayeName");
        return View();
    }

查看

<div class="form-group">
    @Html.LabelFor(x => x.Reshte)
    @Html.DropDownListFor(x => x.Reshte, (SelectList) ViewBag.Reshte, "-- رشته دانش آموز ---", htmlAttributes: new {@class = "form-control"})
</div>
<div class="form-group">
    @Html.LabelFor(x => x.Paye)
    @Html.DropDownListFor(x => x.Paye, (SelectList) ViewBag.Paye, "-- پایه تحصیلی دانش آموز --", htmlAttributes: new {@class = "form-control"})
</div>

  

具有键＆＃39; Reshte＆＃39;的ViewData项。属于＆＃39; System.Int32＆＃39;但必须属于＆＃39; IEnumerable＆＃39;。

 public partial class Tbl_Reshte
{
    public Tbl_Reshte()
    {
        Tbl_Pye_Reshte = new HashSet<Tbl_Pye_Reshte>();
    }

    [Key]
    public int ReshteID { get; set; }

    [StringLength(100)]
    public string ReshteName { get; set; }

    public virtual ICollection<Tbl_Pye_Reshte> Tbl_Pye_Reshte { get; set; }
}

 public partial class Tbl_Paye
{
    public Tbl_Paye()
    {
        Tbl_Pye_Reshte = new HashSet<Tbl_Pye_Reshte>();
    }

    [Key]
    public int PayeID { get; set; }

    [StringLength(100)]
    public string PayeName { get; set; }

    public virtual ICollection<Tbl_Pye_Reshte> Tbl_Pye_Reshte { get; set; }
}

Answer 1

您必须定义新的viewModel，如下所示

 public class SampleViewModel
 {
    [Display(Name = "رشته")]
    [Required(ErrorMessage = "لطفا یکی از رشته ها را انتخاب نمایید")]
    public int ReshteId { get; set; }
    public List<SelectListItem> ReshteSelectListItems { get; set; }

    [Display(Name = "پایه تحصیلی")]
    [Required(ErrorMessage = "لطفا یکی از پایه ها را انتخاب نمایید")]
    public int PayeId { get; set; }
    public List<SelectListItem> PayeSelectListItems { get; set; }

    //other field....
 }

和您的控制器

public ActionResult Add()
    {
        var model = new SampleViewModel
        {
            PayeSelectListItems = _db.paye.Select(p=>new SelectListItem {Text =p.PayeName ,Value = PayeID.tostring() }).toList(),
            //ReshteSelectListItems = ...

        };
        return View(model);
    }

最后是查看

@Html.DropDownListFor(p => p.ReshteId, Model.ReshteSelectListItems , new { @class = "form-control" })