public async void UpdateTeacher(int classId, int teacherId, CreateTeacherDto teacherDto)
        {
            var teacher = await GetTeacherById(classId, teacherId);

            teacher.FirstName   = teacherDto.FirstName;
            teacher.LastName    = teacherDto.LastName;
            teacher.DateOfBirth = teacherDto.DateOfBirth;
            teacher.Pesel       = teacherDto.Pesel;
            teacher.IsFormTutor = teacherDto.IsFormTutor;
            teacher.Subject     = teacherDto.Subject;

            await _context.SaveChangesAsync();
        }
        public async Task <int> CreateTeacher(int classId, CreateTeacherDto teacherDto)
        {
            var @class = await GetClassById(classId);

            var teacher = _mapper.Map <Teacher>(teacherDto);

            teacher.ClassId = classId;

            @class.Teachers.Add(teacher);
            await _context.SaveChangesAsync();

            return(teacher.Id);
        }