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

问题

My code is like this

 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; }
    }
}

Controller

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

And in my view

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

Everything looks okay to me, But it throws an error

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

Can anyone point out what I am doing wrong here?

回答1:

The mistake is you are putting it in ViewBag.ProcedureSubCategoryID while you are passing ProcedureID int Html.DropDownList() and also you are passing SelectList parameter null. A quick fix is to just replace ProcedureSubCategoryID with ProcedureID in Html.DropDownList() as key in first parameter:

you have three ways to resolve this.

Way 1:

Instead of passing null in second parameter which accepts of type SelectListyou can do something like this:

@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" })

Way 3:

or alternative is to store it in ProcedureID in your action:

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

and in View:

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

回答2:

I suppose you're missing something like

ViewBag.ProcedureID = new SelectList(db.ProcedureCategory, "ID", "Name");

I think you have to inizialize ViewBag.ProcedureId

来源：https://stackoverflow.com/questions/27916642/there-is-no-viewdata-item-of-type-ienumerableselectlistitem-that-has-the-key