MVC复选框列表始终返回null

Question

我是MVC新手并构建一个包含一些表单字段的页面，然后是一个数据列表，其中列表中的每个项目都有一个复选框。

用户填写表单并检查所需的复选框，然后提交表单。问题是复选框列表总是返回null。

查看模型 - 有关客户端和用户的信息，然后是要显示复选框的列表。

public class ClientUserViewModel
{
    public Client ClientDetail { get; set; }
    public ClientUser ClientUserDetail { get; set; }
    public List<ClientSite> ClientSitesList { get; set; }
}

客户端网站模型 - 网站列表的数据和SelectedSites保持复选框状态

public class ClientSite
{
        public int SiteId { get; set; }
        public int ClientId { get; set; }
        public string SiteName { get; set; }
        public string Address1 { get; set; }
        public string Address2 { get; set; }
        public string Town { get; set; }
        public string County { get; set; }
        public string Postcode { get; set; }
        public string Tel { get; set; }
        public string Email { get; set; }
        public bool Enabled { get; set; }
        public bool SelectedSites { get; set; }
}

列出视图的一部分

@foreach (var item in Model.ClientSitesList)
        {
                <tr>
                    <td>@item.SiteName</td>
                    <td>
                        @{
                            string fullAddress = "";

                            fullAddress += (String.IsNullOrEmpty(@item.Address1) ? "" : @item.Address1);
                            fullAddress += (String.IsNullOrEmpty(@item.Address2) ? "" : ", " + @item.Address2);
                            fullAddress += (String.IsNullOrEmpty(@item.Town) ? "" : ", " + @item.Town);
                            fullAddress += (String.IsNullOrEmpty(@item.Postcode) ? "" : ", " + @item.Postcode);
                        }
                        @fullAddress
                    </td>
                    <td>@item.Tel</td>
                    <td><a href="mailto:@(item.Email)">@item.Email</a></td>
                    <td style="text-align:right;">
                        @Html.CheckBoxFor(model => item.SelectedSites, new { @class = "form-control chk"})
                    </td>
                </tr>
        }

控制器

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(ApplicationDbContext DbContext, ClientUserViewModel model, List<ClientSite> ClientSitesList)
    {

               // create new user under selected client
                try
                {
                    if (ModelState.IsValid)
                    {
                        IdentityResult ir;
                        var rm = new RoleManager<IdentityRole>(new RoleStore<IdentityRole>(DbContext));
                        //ir = rm.Create(new IdentityRole("pxpuser"));

                        var um = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(DbContext));
                        um.UserValidator = new UserValidator<ApplicationUser>(UserManager)
                        {
                            AllowOnlyAlphanumericUserNames = false
                        };

                        var user = new ApplicationUser()
                        {
                            UserName = model.ClientUserDetail.Email,
                            Email = model.ClientUserDetail.Email,
                            FirstName = model.ClientUserDetail.Firstname,
                            LastName = model.ClientUserDetail.Surname,
                            UserGroup = "Client"
                        };

                        ir = um.Create(user, model.ClientUserDetail.Password);

                        if (ir.Succeeded == false)
                        {
                            Response.Write(ir.Errors);
                            return View(model);
                        }
                        else
                        {
                            // add new user to pxpclient role
                            ir = um.AddToRole(user.Id, "pxpclient");



                            // insert sites user has access to
                            foreach (var site in model.ClientSitesList)
                            {
                                if (site.SelectedSites == true)
                                {
                                    var userSites = new PgsUsersSite()
                                    {
                                        UserId = user.Id,
                                        SiteId = site.SiteId
                                    };
                                    context.PgsUsersSites.InsertOnSubmit(userSites);
                                    context.SubmitChanges();
                                }
                            }


                            // insert new client user details
                            var clientUser = new PgsUser()
                            {
                                UserId = user.Id,
                                ClientId = model.ClientDetail.ClientId,
                                Email = model.ClientUserDetail.Email,
                                Firstname = model.ClientUserDetail.Firstname,
                                Surname = model.ClientUserDetail.Surname,
                                AppointmentBooked = model.ClientUserDetail.AppointmentBooked,
                                PostVisit = model.ClientUserDetail.PostVisit,
                                PxOffer = model.ClientUserDetail.PxOffer,
                                SurveyInstruction = model.ClientUserDetail.SurveyInstruction,
                                EstateAgentInstruction = model.ClientUserDetail.EstateAgentInstruction,
                                BuyinExchange = model.ClientUserDetail.BuyinExchange,
                                BuyinNotes = model.ClientUserDetail.BuyinNotes,
                                SolicitorInstruction = model.ClientUserDetail.SolicitorInstruction,
                                AccessCaseDetails = model.ClientUserDetail.AccessCaseDetails,
                                AccessFeedback = model.ClientUserDetail.AccessFeedback,
                                AccessImages = model.ClientUserDetail.AccessImages,
                                AccessValuations = model.ClientUserDetail.AccessValuations,
                                AccessPxOffer = model.ClientUserDetail.AccessPxOffer,
                                AccessLegal = model.ClientUserDetail.AccessLegal,
                                AccessReports = model.ClientUserDetail.AccessReports
                            };
                            context.PgsUsers.InsertOnSubmit(clientUser);
                            context.SubmitChanges();





                        }

                        return RedirectToAction("Edit", "Clients", new { id = model.ClientUserDetail.ClientId });

                    }
                }
            catch (Exception ex)
            {

                ModelState.AddModelError(string.Empty, ex.Message);
            }



            return View(model);
}

因此，无论选择了多少个复选框，model.ClientSitesList始终都会返回null。