public Teacher[] GetAggregatedTeachers() { string[] allTeachers = _teachersRepository.SelectAllTeachers(); Teacher[] teachers = _teachersRepository.SelectAggregatedTeachers(); List <Teacher> result = new List <Teacher>(); foreach (var teacherName in allTeachers) { Teacher teacher = teachers.FirstOrDefault(t => t.Name == teacherName); if (teacher != null) { result.Add(teacher); } else { result.Add(new Teacher(teacherName)); } } return(result.ToArray()); }