没有类型为'IEnumerable <selectlistitem>'的ViewData项

Question

我和其他人有同样的问题我已经尝试过他们的解决方案，但没有一个能解决我的问题。 错误显示：

  

没有类型为'IEnumerable'的ViewData项   有关键'doctorroleID

在“提交”之后，错误显示但数据完全存储在数据库中。

这是我的观点：

<div class="form-group">
            @Html.LabelFor(model => model.doctorroleID, "doctorroleID", htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownList("doctorroleID", null, htmlAttributes: new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.doctorroleID, "", new { @class = "text-danger" })
            </div>
</div>

这是我的控制者：

public ActionResult Create()
        {  ViewBag.doctorroleID = new SelectList(db.DoctorRoles, "doctorroleID", "doctorrole1");

            return View();
        }

        // POST: Doctor/Create
        [HttpPost]
        public ActionResult Create(DoctorProfile doctor, AdminProfile admin)
        {
            if (ModelState.IsValid)
            {
                using (var db = new eoperadbEntities())
                {
                    var crypto = new SimpleCrypto.PBKDF2();
                    var encrpPass = crypto.Compute(doctor.password);
                    var sysUser = db.DoctorProfiles.Create();

                    sysUser.doctorlastname = doctor.doctorlastname;
                    sysUser.doctorfirstname = doctor.doctorfirstname;
                    sysUser.doctormiddlename = doctor.doctormiddlename;
                    sysUser.doctorcontactnumber1 = doctor.doctorcontactnumber1;
                    sysUser.doctorcontactnumber2 = doctor.doctorcontactnumber2;
                    sysUser.doctoremail = doctor.doctoremail;

                    sysUser.doctorroleID = doctor.doctorroleID;
                    sysUser.doctorimage = doctor.doctorimage;

                    sysUser.username = doctor.username;
                    sysUser.password = encrpPass;
                    sysUser.passwordSalt = crypto.Salt;
                    sysUser.status = "Active";

                    db.DoctorProfiles.Add(sysUser);
                    db.SaveChanges();

                    var log = db.AccountsLogs.Create();
                    var doctorID = db.DoctorProfiles.Where(a => a.username == doctor.username).FirstOrDefault();
                    log.accountaffectedid = doctor.doctorID;
                    log.accountslogID = admin.adminID;
                    log.date = DateTime.Now;
                    log.operation = "Create";
                    db.AccountsLogs.Add(log);
                    db.SaveChanges();
                }
                ModelState.Clear();
                ViewBag.Message = doctor.username + "Successfully registered!";
            }
            return View();
        }