没有类型为'IEnumerable <SelectListItem>'的ViewData项具有键"key"

Question

我的代码是这样的

 namespace DiagnosisApp.Models
{
    public class ProcedurePrice
    {
        public int ID { get; set; }


        public int DepartmentID { get; set; }
        public int ProcedureID { get; set; }
        public int InsuranceProviderID { get; set; }
        public int ProcedureCategoryID { get; set; }
        public int ProcedureSubCategoryID { get; set; }



        [ForeignKey("ID")]
        public virtual Department Department { get; set; }

        [ForeignKey("ID")]
        public virtual InsuranceProvider InsuranceProvider { get; set; }

        [ForeignKey("ID")]
        public virtual ProcedureCategory ProcedureCategory { get; set; }
        [ForeignKey("ID")]
        public virtual ProcedureSubCategory ProcedureSubCategory { get; set; }
    }
}

调节器

  public ActionResult Create()
        {
            ViewBag.DepartmentID = new SelectList(db.Departments, "ID", "Name");
            ViewBag.ProcedureSubCategoryID = new SelectList(db.ProcedureSubCategories, "ID", "Name");
            return View();
        }

在我看来

 @Html.DropDownList("ProcedureID", null, new { @class = "form-control" })
  @Html.ValidationMessageFor(model => model.ProcedureID)

一切看起来都没问题,但它会引发错误

There is no ViewData item of type 'IEnumerable<SelectListItem>' that has the key 'ProcedureID'.

谁能指出我在这里做错了什么？

Answer 1

错误是你在ViewBag.ProcedureSubCategoryID传递ProcedureIDint 时将它放入,Html.DropDownList()并且你传递SelectList参数null.快速解决方法是 在第一个参数中替换ProcedureSubCategoryID为ProcedureIDin Html.DropDownList()作为键:

你有三种方法来解决这个问题.

方式1:

而不是传递null接受类型的第二个参数,SelectList你可以这样做:

@Html.DropDownList("ProcedureID", ViewBag.ProcedureSubCategoryID as SelectList, new  { @class="form-data" })

Way2:

public ActionResult Create()
{
  ViewBag.DepartmentID = new SelectList(db.Departments, "ID", "Name");
  ViewBag.ProcedureSubCategoryID = new SelectList(db.ProcedureSubCategories, "ID", "Name");
  return View();
}


@Html.DropDownList("ProcedureSubCategoryID", null, new { @class = "form-control" })

方式3:

或者替代方法是将其存储ProcedureID在您的操作中:

public ActionResult Create()
{
       ViewBag.DepartmentID = new SelectList(db.Departments, "ID", "Name");
       ViewBag.ProcedureID = new SelectList(db.ProcedureSubCategories, "ID", "Name");
       return View();
}

在视图中:

@Html.DropDownList("ProcedureID", null, new { @class = "form-control" })