没有类型为“IEnumerable”的 ViewData 项具有键“键”

本文关键字：ViewData SelectListItem 类型 IEnumerable | 更新日期: 2023-09-27 18:37:14

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; }
    }
}

控制器

  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)

一切对我来说看起来都很好，但它抛出了一个错误 

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？

没有类型为“IEnumerable<SelectListItem>”的 ViewData 项具有键“键”

错误在于您在传递 int Html.DropDownList() 时将其放入ViewBag.ProcedureSubCategoryID ProcedureID并且您正在传递SelectList参数null。一个快速解决方法是将ProcedureSubCategoryID替换为Html.DropDownList()中的ProcedureID作为第一个参数中的键：

您有三种方法可以解决此问题。

方式1：

与其在接受类型 SelectList 的第二个参数中传递null，不如执行以下操作：

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

方式2：

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：

或者另一种方法是将其存储在操作中的ProcedureID中：

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

并在视图中：

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

我想你错过了类似的东西 

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

我认为你必须初始化ViewBag.ProcedureId

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