如何在ViewModel中使用foreach循环？

Question

我需要在我的视图中使用ViewModel，但出现错误Null引用异常（foreach（模型中的var项））（item = null）。我该如何克服呢？

控制器：

public async Task<IActionResult> Index(int? page)
        {
            var pagesList = from m in _BSXCertAssignmentsItem.All select m;

            int pageSize = 20;
            int pageNumber = (page ?? 1);
            var pagedPages = pagesList.ToPagedList(pageNumber, pageSize) as PagedList<BSXCertAssignmentsViewModel>;

            var idlist = _BSXCSRServiceItem.All.Where(x => x.SERVICE_ID != 0);

            return View(pagedPages);
        }

ViewModel：

public class BSXCertAssignmentsViewModel
    {
        public BSXCertAssignments certAssignments { get; set; }
        public BSXCSRService service { get; set; }
    }

查看：

@model PagedList<BSXCertAssignmentsViewModel>
.
.
.
 @foreach (var item in Model)
                            {
                                <tr class="clickable-row" data-href="/BSXMCertAssignments/Edit/@item.certAssignments.CERT_ASSIGNMENT_ID">
                                    <td>
                                        @Html.DisplayFor(modelItem => item.certAssignments.CERT_ASSIGNMENT_ID)
                                    </td>
                                    <td>
                                        @Html.DisplayFor(modelItem => item.certAssignments.CERT_ASSIGNMENT_NAME)
                                    </td>
                                    <td>
                                        @Html.DisplayFor(modelItem => item.certAssignments.SERVICE_ID)
                                    </td>
                                    <td>
                                        @Html.DisplayFor(modelItem => item.certAssignments.REG_ID)
                                    </td>
                                    <td style="width:120px">
                                        <a asp-action="Delete" asp-route-id="@item.certAssignments.CERT_ASSIGNMENT_ID">
                                            <div class="bt_cl admin-bt-dl">
                                                <i class="fa fa-trash-o admin-icon pull-left" aria-hidden="true"></i>
                                            </div>
                                        </a>
                                        <a asp-action="Edit" asp-route-id="@item.certAssignments.CERT_ASSIGNMENT_ID">
                                            <div class="bt_cl admin-bt-edit">
                                                <i class="fa fa-pencil-square-o admin-icon pull-left" aria-hidden="true"></i>
                                            </div>
                                        </a>
                                    </td>
                                </tr>
                            }

我知道当我在“模型”中键入“ var item”时，它应该为null，因为ViewModel本身不包含项目，它只是引用某些模型，但是这种理解并不能帮助我解决问题。