c# - 未获取下拉列表数据

Question

这是我得到的错误，“System.Data.SqlClient.SqlException：'参数化查询'（@name nvarchar（5），@course nvarchar（3），@emailAddr nvarchar（12），@'需要参数' @mentorID'，未提供。' "

I suspect the reason for the error was due to my drop down list data not getting stored as if i have just simply used a textbox , it had work out just fine.

如果你们能提供帮助，不胜感激，非常感谢你们！！

达尔

        public int Create(Student student)
        {
            //Instantiate a SqlCommand object,supply it with an INSERT SQL statement
            //which will return the auto-generated StudentID after insertion,
            //and the connection object for connecting to the database.

            SqlCommand cmd = new SqlCommand
            ("INSERT INTO Student (Name, Course," +
            " EmailAddr,MentorID)" +
             "OUTPUT INSERTED.StudentID "
            + "VALUES(@name, @course,"
            + "@emailAddr,@mentorID)", conn);

            //Define the parameters used in SQL statement, value for each parameter
            //is retrieved from respective class's property.
            cmd.Parameters.AddWithValue("@name", student.Name);
            cmd.Parameters.AddWithValue("@course", student.Course);
            cmd.Parameters.AddWithValue("@emailAddr", student.EmailAddr);
            cmd.Parameters.AddWithValue("@mentorID", student.MentorID);

            //A connection to database must be opened before any operations made.
            conn.Open();
            //ExecuteScalar is used to retrieve the auto-generated
            //StaffID after executing the INSERT SQL statement
            student.StudentID = (int)cmd.ExecuteScalar();
            //A connection should be closed after operations.
            conn.Close();
            //Return id when no error occurs.
            return student.StudentID;
        }

控制器 // GET: Student/Create public ActionResult CreateProfile() { ViewData["StudentList"] = studentContext.GetAllStudent(); 列出导师列表=讲师上下文.GetAllLecturer(); List selectedMentorList = new List(); foreach（导师列表中的讲师 m）{ selectedMentorList.Add（新 SelectListItem { Value = m.LecturerID.ToString(), Text = m.LecturerID.ToString() }); }

            ViewData["MentorList"] = selectedMentorList;
            return View("CreateProfile");
        }

        // POST: Student/Create
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult CreateProfile(Student student)
        {
            ViewData["StudentList"] = studentContext.GetAllStudent();
            student.Password = "p@55Student";
            if (ModelState.IsValid)
            {

                student.StudentID = studentContext.Create(student);
                return RedirectToAction("CreateSuccess"); 
            }
            else
            {
                //Input validation fails, return to the Create view
                return View(student);
            }

        }

看法

  <div>
                    <label asp-for="MentorID"></label>
                    <input type="hidden" asp-for="MentorID" />
                    <select asp-for="MentorID"asp-items="@ViewData["MentorList"]
                                        as List<SelectListItem>"></select>
                </div>

标签： c#asp.netmodel-view-controller