public IActionResult Post([FromBody] PatientModel obj)
        {
            var context = new ValidationContext(obj, null, null);
            var result  = new List <ValidationResult>();
            var isValid = Validator.TryValidateObject(obj, context, result, true);

            if (result.Count == 0)
            {
                PatientData dal = new PatientData();
                dal.Database.EnsureCreated();
                dal.Add(obj);      //add in memory
                dal.SaveChanges(); //physical memory
                List <PatientModel> recs = dal.PatientModels.ToList <PatientModel>();
                return(StatusCode(200, recs));
            }
            else
            {
                return(StatusCode(500, (result)));
            }
        }