private void SortByDrivingSchoolTeacher(ListSortDirection?direction)
 {
     if (direction == ListSortDirection.Ascending)
     {
         TraineesList = TraineesList.OrderBy(trainee => trainee.DrivingSchoolTeacher).ToList();
     }
     else if (direction == ListSortDirection.Descending)
     {
         TraineesList = TraineesList.OrderByDescending(trainee => trainee.DrivingSchoolTeacher).ToList();
     }
     else
     {
         TraineesList = TraineesList.OrderBy(trainee => trainee.DrivingSchoolTeacher).ToList();
     }
 }
 private void SortByGearType(ListSortDirection?direction)
 {
     if (direction == ListSortDirection.Ascending)
     {
         TraineesList = TraineesList.OrderBy(trainee => trainee.GearType).ToList();
     }
     else if (direction == ListSortDirection.Descending)
     {
         TraineesList = TraineesList.OrderByDescending(trainee => trainee.GearType).ToList();
     }
     else
     {
         TraineesList = TraineesList.OrderBy(trainee => trainee.GearType).ToList();
     }
 }
 private void SortByDaysPassed(ListSortDirection?direction)
 {
     if (direction == ListSortDirection.Ascending)
     {
         TraineesList = TraineesList.OrderBy(trainee => trainee.DaysPassedSinceLastTest).ToList();
     }
     else if (direction == ListSortDirection.Descending)
     {
         TraineesList = TraineesList.OrderByDescending(trainee => trainee.DaysPassedSinceLastTest).ToList();
     }
     else
     {
         TraineesList = TraineesList.OrderBy(trainee => trainee.DaysPassedSinceLastTest).ToList();
     }
 }
 private void SortByDateOfBirth(ListSortDirection?direction)
 {
     if (direction == ListSortDirection.Ascending)
     {
         TraineesList = TraineesList.OrderBy(trainee => trainee.DateOfBirth).ToList();
     }
     else if (direction == ListSortDirection.Descending)
     {
         TraineesList = TraineesList.OrderByDescending(trainee => trainee.DateOfBirth).ToList();
     }
     else
     {
         TraineesList = TraineesList.OrderBy(trainee => trainee.DateOfBirth).ToList();
     }
 }