public async Task <IEnumerable <TradeOffer> > GetBuyOffers(DateTime oldestTradeDate, IEnumerable <int> localTradePointIds) { return(await context.Set <TradeOffer>().Where( t => t.OfferType == OfferType.Buy && t.DateTimeOfOffer >= oldestTradeDate && localTradePointIds.Contains(t.TradePointId))?.ToListAsync() ?? Enumerable.Empty <TradeOffer>()); }