在post方法中初始化新列表时,下拉列表为空

我的控制器中有以下内容:

using System.Collections.Generic;
using System.Configuration;
using System.Data.Entity;
using System.Data.SqlClient;
using System.Linq;
using System.Net;
using System.Web.Mvc;
using ContactReport_MVC.Models;

namespace ContactReport_MVC.Controllers
{
    public class ReportsController : Controller
    {
        private ReportDBContext db = new ReportDBContext();

        // GET: Reports
        public ActionResult Index()
        {
            return View(db.Reports.ToList());
        }

        // GET: Reports/Details/5
        public ActionResult Details(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            Report report = db.Reports.Find(id);
            if (report == null)
            {
                return HttpNotFound();
            }
            return View(report);
        }

        // GET: Reports/Create
        public ActionResult Create()
        {
            var model = new Report();
            model.ContactsList = GetContacts();
            return View(model);
        }

        // POST: Reports/Create
        // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
        // more details see https://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create(Report report)
        {
            if (ModelState.IsValid)
            {
                db.Reports.Add(report);
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            var model = new Report();
            return View(model);
        }

        // GET: Reports/Edit/5
        public ActionResult Edit(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            Report report = db.Reports.Find(id);
            if (report == null)
            {
                return HttpNotFound();
            }
            return View(report);
        }

        // POST: Reports/Edit/5
        // To protect from overposting attacks, please enable the specific properties you want to bind to, for 
        // more details see https://go.microsoft.com/fwlink/?LinkId=317598.
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Edit([Bind(Include = "Id,Contacts,MeetingDate,SubmittedBy,ClientType,Location,ContactName,Purpose,Discussed,Actions")] Report report)
        {
            if (ModelState.IsValid)
            {
                db.Entry(report).State = EntityState.Modified;
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            return View(report);
        }

        // GET: Reports/Delete/5
        public ActionResult Delete(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            Report report = db.Reports.Find(id);
            if (report == null)
            {
                return HttpNotFound();
            }
            return View(report);
        }

        // POST: Reports/Delete/5
        [HttpPost, ActionName("Delete")]
        [ValidateAntiForgeryToken]
        public ActionResult DeleteConfirmed(int id)
        {
            Report report = db.Reports.Find(id);
            db.Reports.Remove(report);
            db.SaveChanges();
            return RedirectToAction("Index");
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                db.Dispose();
            }
            base.Dispose(disposing);
        }

        private static List<SelectListItem> GetContacts()
        {
            List<SelectListItem> items = new List<SelectListItem>();
            string constr = ConfigurationManager.ConnectionStrings["650sContactReportConnectionString"].ConnectionString;
            using (SqlConnection con = new SqlConnection(constr))
            {
                string query = @"SELECT  TOP 1000   e.DisplayEmployeeId as [Id], EmployeeDescNoID as [Name]
                                FROM [Cascade].[dbo].[Employee] e
                                join [Cascade].[dbo].[EmployeeJobs] ej on e.employeeid = ej.EmployeeId
                                Where
                                (e.leftdate is null 
                                and ej.sys_ActiveJob = 1)
                                order by surname asc";
                using (SqlCommand cmd = new SqlCommand(query))
                {
                    cmd.Connection = con;
                    con.Open();
                    using (SqlDataReader sdr = cmd.ExecuteReader())
                    {
                        while (sdr.Read())
                        {
                            items.Add(new SelectListItem
                            {
                                Text = sdr["Name"].ToString(),
                                Value = sdr["Id"].ToString()
                            });
                        }
                    }
                    con.Close();
                }
            }

            return items;
        }
    }
}

如果我尝试使用此(at/reports/create)发布表单,则会得到以下错误:

System.InvalidOperationException:“没有类型为”IEnumerable“且具有键”contacts“的ViewData项。”

我可以把它放进控制器来解决这个问题: report.ContactsList = new List<SelectListItem>(); 但是我的下拉列表显示为空。

我的HTML助手如下所示:

@Html.DropDownListFor(model => model.Contacts, Model.ContactsList, new { @class = "form-control js-data", @multiple = "multiple", @placeholder = "Type here to search, press enter or tab to select" })

我想我在问如何从控制器传递填充列表 Create 方法,进入 Post 方法,以便将其提交到数据库。

另外,如何将列表的值(多选下拉列表)存储到模型中定义的字符串字段中 Contacts ?

型号代码:

 public class Report
 {
        public int Id { get; set; }

        [Required]
        [Display(Name = "Relevant Contacts")]
        public string Contacts { get; set; }

        [Required]
        [Display(Name = "Date of meeting")]
        [DataType(DataType.Date)]
        [DisplayFormat(DataFormatString = "{0:d}", ApplyFormatInEditMode = true)]
        public DateTime MeetingDate { get; set; }

        [Required]
        public string CompanyName { get; set; }
        [Display(Name = "Submitted By")]

        public string SubmittedBy { get; set; }

        [Required]
        [Display(Name = "Client Type")]
        public string ClientType { get; set; }

        [Required]
        [Display(Name = "Location of meeting")]
        public string Location { get; set; }

        [Required]
        [Display(Name = "Client Contact(s)")]
        public string ContactName { get; set; }

        [Required]
        [Display(Name = "Purpose of meeting")]
        public string Purpose { get; set; }

        [AllowHtml]
        [Required]
        [Display(Name = "What was discussed")]
        [Column(TypeName = "varchar(MAX)")]
        public string Discussed { get; set; }

        [AllowHtml]
        [Required]
        [Display(Name = "Actions to take")]
        [Column(TypeName = "varchar(MAX)")]
        public string Actions { get; set; }

        [NotMapped]
        public IEnumerable<SelectListItem> ContactsList { get; set; }

}

public class ReportDBContext : DbContext 
{
        public DbSet<Report> Reports  { get; set; }

}