没有“IEnumerable<SelectListItem>"类型的 ViewData 项具有密钥“key"的

问题描述

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)

我觉得一切正常，但它抛出了一个错误

Everything looks okay to me, But it throws an error

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?

Can anyone point out what I am doing wrong here?

推荐答案

错误是你把它放在 ViewBag.ProcedureSubCategoryID 中，而你在传递 ProcedureID int Html.DropDownList() 并且您正在传递 SelectList 参数 null.一个快速的解决方法是将 Html.DropDownList() 中的 ProcedureSubCategoryID 替换为 ProcedureID 作为第一个参数的键:

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:

您可以通过三种方法解决此问题.

you have three ways to resolve this.

不是在接受 SelectList 类型的第二个参数中传递 null 你可以做这样的事情:

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" })

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:

或者替代方法是将其存储在您的操作中的 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" })

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