Linq查询空例外或无结果

Question

I'm working on the below Linq query that I can't quite get to work. My issue is that I get a null reference or no results (if I keep the "if" statement in the for loop I have). The query is supposed to provide the top 20 result times by event_number.

var queryByEventNumber = EventNumbers
.GroupJoin(EntryEvents, e => e.Id, ee => ee.EventNumberId, (e, g) => new
{
    EventNumber = e,
    EntryEvents = g
})
.OrderBy(e => e.EventNumber.Event_Number);

foreach (var group in queryByEventNumber)
{
    Console.WriteLine($"EventNumber: { group.EventNumber.Event_Number}");

//If statement apparently always returns false at this point
//If I remove if statement, I get a null reference on group.EntryEvents.OrderBy(r => r.Result.AdjustTime)...

    if(Results.Any(r => r.EntryEvents.Any(g => g.EventNumberId == group.EventNumber.Id)))
    {
        foreach (var result in group.EntryEvents.OrderBy(r => r.Result.AdjustedTime).Take(20))
        {
            Console.WriteLine($"\t\t{result.Result.AdjustedTime} : {result.Result.DateCreated.Year}");
        }
    }
}

The issue is that I don't have results for every eventnumber (eventually I will but I believe I need to be able to handle it either way). I've tried a few variations to the if statement but no luck. Any help is appreciated. Thanks!

Answer 1

Ok, so after a bunch of trial and error, I went with this solution. Not sure it is optimal, but it works...

var eventNumbers = EventNumbers.Where(e => e.Active).OrderBy(e => e.Event_Number).ToList();

foreach (var en in EventNumbers)
{
    Console.WriteLine($"EventNumber: {en.Event_Number}");

    var results = Results
    .Where(r => r.EntryEvent.EventNumberId == en.Id && !r.Disqualified && r.Active && !r.EntryEvent.Scratched)
    .OrderBy(r => r.AdjustedTime)
    .Take(20);
    if (results != null)
    {
        foreach (var result in results)
        {
            Console.WriteLine($"Time: {result.AdjustedTime}");
        }
    }
}