如何从 linq-to-sql 查询实现自定义返回类型的排序？

Question

我正在使用带有 linq-to-sql 的存储库类作为（Web）GridView 的对象数据源。 GridView 必须允许对所有列进行排序。我有一个使用 这种方法，但我显然更愿意在没有预定义的排序表达式列表的情况下执行此操作。

public class TrailerMovementRepository
{
    private TrailerMovementDataContext db = new TrailerMovementDataContext();

    public IOrderedEnumerable<TrailerMovementHistory> GetTrailerMovementHistoryByDepotAndDate(string depot, DateTime searchDate, string sortExpression)
    {
        var unorderedQuery = (from tm in db.TrailerMovements
               where tm.Depot == depot && tm.Date_In == searchDate && tm.Time_Out != null               
               select new TrailerMovementHistory
               {
                   Depot = tm.Depot,
                   TrailerNumber = tm.Trailer,
                   TimeIn = tm.Time_In,
                   TimeOut = tm.Time_Out,
                   VOR = tm.VOR.Value,
                   Contents = tm.Contents,
                   Supplier = tm.Supplier,
                   TurnaroundTime = FormatDuration(tm.Time_Out - tm.Time_In),
                   VORTime = FormatDuration(tm.VOnR_Date - tm.VOffR_Date),
                   LoadedTime = tm.LoadedTime,
                   Destination = tm.Destination
               }).ToList<TrailerMovementHistory>();

        //need to find a way to dynamically do this from the passed in expression
        IOrderedEnumerable<TrailerMovementHistory> orderedQuery = unorderedQuery.OrderBy(t => t.TrailerNumber);

        switch (sortExpression)
        {
            case "TrailerNumber DESC":
                orderedQuery = unorderedQuery.OrderByDescending(t => t.TrailerNumber);
                break;
            case "TimeIn":
                orderedQuery = unorderedQuery.OrderBy(t => t.TimeIn);
                break;
            case "TimeIn DESC":
                orderedQuery = unorderedQuery.OrderByDescending(t => t.TimeIn);
                break;

            ...etc...

            default:
                break;
        }
        return orderedQuery;
    }

    public class TrailerMovementHistory
    {
        public TrailerMovementHistory()
        { }
        public String Depot { get; set; }
        public String TrailerNumber { get; set; }
        public DateTime? TimeIn { get; set; }
        public DateTime? TimeOut { get; set; }
        public Boolean VOR { get; set; }
        public String Contents { get; set; }
        public String Supplier { get; set; }
        public String TurnaroundTime { get; set; }
        public String VORTime { get; set; }
        public DateTime? LoadedTime { get; set; }
        public String Destination { get; set; }

    }
}

Answer 1

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