public IQueryable <maintenance_system_device_model> FindAll()
        {
            var result = _context.maintenance_system_devices.ToList().Select(d => new maintenance_system_device_model()
            {
                maintenance_system_name = _context.maintenance_systems
                                          .Where(t => t.id == d.id_maintenance_system)
                                          .Select(d => d.name).SingleOrDefault(),
                createby_name = _context.users
                                .Where(t => t.Id == d.create_by)
                                .Select(d => d.FirstName + " " + d.LastName).SingleOrDefault(),
                db = d,
            }).ToList();

            for (int i = 0; i < result.Count(); i++)
            {
                result[i].list_system_device_detail = _context.maintenance_system_device_list_details.ToList().Where(m => m.id_system_device == result[i].db.id).Select(m =>
                {
                    maintenance_system_device_detail_db dbSystemDeviceDetail = _context.maintenance_system_device_details.Where(d => d.status_del == 1).Where(d => d.id == m.id_system_device_detail).SingleOrDefault();
                    if (dbSystemDeviceDetail == null)
                    {
                        return(null);
                    }
                    return(new maintenance_system_device_list_detail_model
                    {
                        model = dbSystemDeviceDetail.model,
                        db = m,
                        name = dbSystemDeviceDetail.name,
                        specification_name = dbSystemDeviceDetail.specification_name,
                    });
                }).ToList()
                ;
                result[i].list_system_device_detail = result[i].list_system_device_detail.Where(i => i != null).ToList();
            }
            return(result.AsQueryable());
        }
 public maintenance_system_device_detail_model()
 {
     db = new maintenance_system_device_detail_db();
 }