public void Write(string fileName, CalculatorSave model)
        {
            string targetFolder = HttpContext.Current.Server.MapPath("~/Save");
            string targetPath   = Path.Combine(targetFolder, fileName);

            File.WriteAllText(targetPath, JsonConvert.SerializeObject(model));
        }
        // POST: api/Calculator
        public string Post([FromBody] CalculatorSave calculator)
        {
            try
            {
                if (string.IsNullOrEmpty(calculator.User))
                {
                    calculator.User = "******";
                }
                var data = db.t_save
                           .Where(w => w.id == calculator.User).FirstOrDefault();

                if (data != null)
                {
                    data.inputA      = calculator.InputA;
                    data.inputB      = calculator.InputB;
                    data.@operator   = calculator.SelectedOperator;
                    data.data_result = calculator.Result;
                }
                else
                {
                    t_save save = new t_save()
                    {
                        id          = calculator.User,
                        inputA      = calculator.InputA,
                        inputB      = calculator.InputB,
                        @operator   = calculator.SelectedOperator,
                        data_result = calculator.Result
                    };

                    db.t_save.Add(save);
                }

                db.SaveChanges();

                return("Success");
            }
            catch (Exception ex)
            {
                return(ex.Message);
            }
        }
        // GET: api/Calculator/5
        public CalculatorSave Get(string id)
        {
            var data = db.t_save
                       .Where(w => w.id == id).FirstOrDefault();

            if (data != null)
            {
                CalculatorSave calculator = new CalculatorSave()
                {
                    InputA           = data.inputA,
                    InputB           = data.inputB,
                    SelectedOperator = data.@operator,
                    Result           = data.data_result
                };

                return(calculator);
            }
            else
            {
                return(null);
            }
        }