Question

I’m having a heck of a time getting this to work – all the working samples online do not fit my need.

I’m trying to sort a child collection while building my entity framework statement..

the problematic line is:

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());

the error i’m receiving is:
System.NotSupportedException: Specified method is not supported.

here is some of my sample code:

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();

i’M at a complete loss and cannot find any solution online how to solve this – I need to do the ordering this way because i’m also doing paging and limiting – if the ordering is done afterwards it will only be ordering that specific "page" or "result set" – instead of ordering the entire result set before the paging takes place (i hope this makes sense.. lol)

thanks in advance!!!

Answer 1

I think changing it like this should help. If not post the full error message

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