private async void FreeParkingSpaces_AddNew() { Days day = new Days(); var listFreeDates = await OwnerFreeSpaces(); var listBlackoutDates = await ListBlackout(); var listWorkingDays = day.WorkingDays(_dateFrom, _dateTo).ToList(); var freeDatesToDelete = from free in listFreeDates select Date.Format(free.Date); var blackoutDatesToDelete = from black in listBlackoutDates select Date.Format(black.Date); var dateToInsert = (from work in listWorkingDays where !freeDatesToDelete.Contains(Date.Format(work.Date)) && !blackoutDatesToDelete.Contains(Date.Format(work.Date)) select Date.Format(work.Date)).ToList(); ParkingEntities1 d = new ParkingEntities1(); foreach (var item in dateToInsert) { ParkingSpace p = new ParkingSpace(); p.Date = item; p.ParkingSpaceOwnerID = _ownerId; p.Added = DateTime.Now; pe.ParkingSpaces.Add(p); pe.SaveChanges(); } }