C# 在实体框架中排序子集合，同时生成动态语句

我花了很长时间来完成这项工作——所有在线工作的样本都不符合我的需要

我试图在构建实体框架语句时对子集合进行排序

问题在于：

TradesFilter = SortDirection.Equals(SortDirection.Ascending) ? TradesFilter.OrderBy(s => s.TradeLineItems.OrderBy(t => t.TradeDateTime).Select(t => t.TradeDateTime).FirstOrDefault()) : TradesFilter.OrderByDescending(s => s.TradeLineItems.OrderByDescending(t => t.TradeDateTime).Select(t => t.TradeDateTime).FirstOrDefault());

我收到的错误是： System.NotSupportedException:不支持指定的方法。

以下是我的一些示例代码：

using (myentities db = new myentities())
    {
        var TradesFilter = db.Trades.Include("TradeLineItems").AsQueryable();

        totalRecords = TradesFilter.Count();

        #region SORTING
        if (SortColumn == "ID")
        {
            TradesFilter = SortDirection.Equals(SortDirection.Ascending) ? TradesFilter.OrderBy(s => s.TradeId) : TradesFilter.OrderByDescending(s => s.TradeId);
        }
        else if (SortColumn == "Title")
        {
            TradesFilter = SortDirection.Equals(SortDirection.Ascending) ? TradesFilter.OrderBy(s => s.Title) : TradesFilter.OrderByDescending(s => s.Title);
        }
        else if (SortColumn == "StockCode")
        {
            TradesFilter = SortDirection.Equals(SortDirection.Ascending) ? TradesFilter.OrderBy(s => s.StockCode) : TradesFilter.OrderByDescending(s => s.StockCode);
        }
        else if (SortColumn == "Company")
        {
            TradesFilter = SortDirection.Equals(SortDirection.Ascending) ? TradesFilter.OrderBy(s => s.Company) : TradesFilter.OrderByDescending(s => s.Company);
        }
        else if (SortColumn == "TradeDate")
        {
            TradesFilter = SortDirection.Equals(SortDirection.Ascending) ? TradesFilter.OrderBy(s => s.TradeLineItems.OrderBy(t => t.TradeDateTime).Select(t => t.TradeDateTime).FirstOrDefault()) : TradesFilter.OrderByDescending(s => s.TradeLineItems.OrderByDescending(t => t.TradeDateTime).Select(t => t.TradeDateTime).FirstOrDefault());
        }
        else if (SortColumn == "Result")
        {
            TradesFilter = SortDirection.Equals(SortDirection.Ascending) ? TradesFilter.OrderBy(s => s.Result) : TradesFilter.OrderByDescending(s => s.Result);
        }
        else
        {
            TradesFilter = TradesFilter.OrderByDescending(s => s.TradeId);
        }
#endregion
/* DO A WHOLE BUNCH MORE STUFF - SORTING, PAGING, LIMITING,FILTERING - ALL CUT OUT AS UNNECESSARY TO THE QUESTION */
Trades = TradesFilter.ToList();

我完全不知所措，无法在网上找到任何解决方案如何解决这个问题-我需要以这种方式进行排序，因为我也在进行分页和限制-如果之后进行排序，它将只排序特定的“页面”或“结果集”-而不是在分页发生之前排序整个结果集（我希望这是有意义的..哈哈）

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提前感谢！！！

我认为这样更改应该会有所帮助。如果没有，请发布完整的错误消息

TradesFilter =
  SortDirection.Equals(SortDirection.Ascending) ?
  TradesFilter.OrderBy(s => s.TradeLineItems.Min(t => TradeDateTime)) :
  TradesFilter.OrderBy(s => s.TradeLineItems.Max(t => TradeDateTime));

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天哪，非常感谢你！！！！！！！！！！！！！！！！！老兄…我一整天都在为这个问题头痛…你太棒了…@Loren-我很高兴我能帮上忙