选择EF Core中的性能问题

Question

        _context.Homestays   
                .Include(x => x.CreatedUser)
                .Include(x => x.UpdatedUser)
                .Include(x => x.HomestayEvaluations)
                .Include(x => x.HomestayContracts)
                .Include(x => x.HomestayPoliceChecks)
                .Include(x => x.HomestayHouseHolds)
                .AsNoTracking()
                .Select(x => new Homestay()
                {
                    HomestayId = x.HomestayId,
                    HomestayFamily = ConstValue.GetHomestayFamilyName(x),
                    Address = x.Address,
                    Score = x.HomestayEvaluations.Any(x1 => x1.IsEvaluationActive) ? x.HomestayEvaluations.LastOrDefault(x1 => x1.IsEvaluationActive).GetScore() : 0,
                    Contract = x.HomestayContracts.Any(x1 => x1.IsContractActive) ? x.HomestayContracts.LastOrDefault(x1 => x1.IsContractActive).ContractDate : null,
                    Students = x.Students,
                    HouseHolders = x.HomestayHouseHolds.Count(x1 => x1.IsHouseHoldActive),
                    PoliceCheck = x.HomestayPoliceChecks.Any(x1 => x1.IsPoliceCheckActive) ? x.HomestayPoliceChecks.LastOrDefault(x1 => x1.IsPoliceCheckActive).PoliceCheckDate : null,
                    Language = x.Language,
                    Room = x.Room,
                    IsActive = x.IsActive,
                    CreatedDate = x.CreatedDate,
                    CreatedUserName = ConstValue.GetUserName(x.CreatedUser),
                    UpdatedDate = x.UpdatedDate,
                    UpdatedUserName = ConstValue.GetUserName(x.UpdatedUser)
                })
                .OrderByDescending(x => x.HomestayId);

Hello, Im wonder that how do I change my select query better ?

This code as below that it looks messy. first excute any and if it is true, get last one. but is there any more short code ??

Contract = x.HomestayContracts.Any(x1 => x1.IsContractActive) ? x.HomestayContracts.LastOrDefault(x1 => x1.IsContractActive).ContractDate : null

I tried without any(), it occred error as null object if there is no data.

Please help me.

Thanks :)

Answer 1

Use this

Contract = x.HomestayContracts.LastOrDefault(x1 => x1.IsContractActive)?.ContractDate ?? null

Also you can disable lazy loading for this query in context's configuration

context.Configuration.LazyLoadingEnabled = false; 

This way you can eliminate Include methods, cause shorter statement but not better performance. Use stored procedure for performance. Stored Procedure in Entity Framework