仅 LINQ to Entities 中的排序输入支持“跳过”方法。必须在方法“Skip”之前调用方法“OrderBy”。答案

【问题标题】：The method 'Skip' is only supported for sorted input in LINQ to Entities. The method 'OrderBy' must be called before the method 'Skip'.仅 LINQ to Entities 中的排序输入支持“跳过”方法。必须在方法“Skip”之前调用方法“OrderBy”。
【发布时间】：2014-09-24 14:20:00
【问题描述】：

我有上述错误，而且很奇怪，因为我没有使用任何“跳过”方法。

我还注意到，我在 switch 语句中的 sortOrder 为空。

您能帮我找出导致此错误的原因吗？

下面是我的代码：

public ActionResult Index(string sortOrder, string currentFilter, string searchString, int? page)
        {
 ViewBag.CurrentSort = sortOrder;
            ViewBag.BookingIdSortParm = String.IsNullOrEmpty(sortOrder) ? "RecordId" : "";
            ViewBag.ItemSortParm = String.IsNullOrEmpty(sortOrder) ? "Cart" : "";
            ViewBag.UserFullNameSortParm = String.IsNullOrEmpty(sortOrder) ? "UserFullName" : "";
            ViewBag.StatusCodeSortParm = String.IsNullOrEmpty(sortOrder) ? "StatusCode" : "";
            ViewBag.RequestDateSortParm = String.IsNullOrEmpty(sortOrder) ? "RequestDate" : "";
            ViewBag.StartDateSortParm = String.IsNullOrEmpty(sortOrder) ? "StartDate" : "";
            ViewBag.EndDateSortParm = String.IsNullOrEmpty(sortOrder) ? "EndDate" : "";

            if (searchString != null)
            {
                page = 1;
            }
            else
            {
                searchString = currentFilter;
            }

            ViewBag.CurrentFilter = searchString;

            var myBookingList = (from s in SystemDB.Users                              
                                where s.UserLogin == strLoginName
                                join b in SystemDB.Carts on s.DepartmentId equals b.Booking.Item.DepartmentId 
                                where b.Stage != 1 && b.Stage != 5                              
                                orderby b.RecordId descending
                                select b).GroupBy(b => b.CartId).Select(y => y.FirstOrDefault());



            if (!String.IsNullOrEmpty(searchString))
            {


                myBookingList = myBookingList.Where(s => s.RecordId.ToString().Contains(searchString.ToUpper())
                                       || s.CartId.ToUpper().Contains(searchString.ToUpper())
                                       || s.Booking.UserFullName.ToUpper().Contains(searchString.ToUpper())
                                       || s.StatusCode.StatusCodeName.ToUpper().Contains(searchString.ToUpper())
                                       || s.Booking.RequestDate.ToString().Contains(searchString.ToUpper())
                                       || s.Booking.StartDate.ToString().Contains(searchString.ToUpper())
                                       || s.Booking.EndDate.ToString().Contains(searchString.ToUpper()));
            }

            switch (sortOrder)
            {
                case "BookingId":
                    myBookingList = myBookingList.OrderByDescending(s => s.RecordId);
                    break;

                case "Cart":
                    myBookingList = myBookingList.OrderBy(s => s.CartId);
                    break;

                case "UserFullName":
                    myBookingList = myBookingList.OrderBy(s => s.Booking.UserFullName);
                    break;

                case "StatusCode":
                    myBookingList = myBookingList.OrderBy(s => s.StatusCode.StatusCodeName);
                    break;

                case "RequestDate":
                    myBookingList = myBookingList.OrderByDescending(s => s.Booking.RequestDate);
                    break;

                case "StartDate":
                    myBookingList = myBookingList.OrderByDescending(s => s.Booking.StartDate);
                    break;

                case "EndDate":
                    myBookingList = myBookingList.OrderByDescending(s => s.Booking.EndDate);
                    break;

                //default:
                //    throw new ArgumentException("Bad sort order specified", "sortOrder");

            }

            int pageSize = 5;
            int pageNumber = (page ?? 1);


            return View(myBookingList.ToPagedList(pageNumber, pageSize));
}

【问题讨论】：

如果您在排序中添加了默认排序，它应该可以工作。

标签： c# asp.net asp.net-mvc linq entity-framework

【解决方案1】：

ToPagedList 的实现将使用Skip 和Take 来获取查询的每一页。

【讨论】：

【解决方案2】：

设置默认排序顺序而不是评论它会起作用。
而不是这个

//default:
//    throw new ArgumentException("Bad sort order specified", "sortOrder");

试试这个或设置一些默认顺序

default:
myBookingList = myBookingList.OrderByDescending(s => s.RecordId);
break;

希望对你有帮助

【讨论】：