public async Task <IActionResult> All()
        {
            var data  = (await _classService.All());
            var data2 = data
                        .Select(@class => new ClassViewModel
            {
                Id          = @class.Id,
                ClassCode   = @class.ClassCode,
                ClassName   = @class.ClassName,
                CareerNames = @class.CareerNames,
                Careers     = @class.Careers
            });

            return(Ok(data2));
        }