Controller creates new instance of Class after ButtonClick

Question

User-462092770 posted

I Have a simple calculator (in asp.net mvc c#) so far its starting and i can use the buttons but after every click there is a new instance of my Class.

Do i need a Database to store the result and use it for the next interaction or is there a easier way(another way)?????

for example if i want to type 22 it will write 2 an clear textbox and write 2. My Calculator Class works in my WebForms project just fine .

Answer 1

User1686398519 posted

Hi Jonny0024,

1. there is a new instance of my Class
   • Since you did not provide some code, I cannot reproduce your problem.
2. Do i need a Database to store the result
   • You can store the result in the database after calculating the result.
   • I make an example, you can refer to it.

Model

    public class Calculator
    {
        [Key]
        public int Id { get; set; }
        public string CalculatorExpression { get; set; }
        public string CalculatorResult { get; set; }
    }

HomeController

        public CalculatorDemoContext db = new CalculatorDemoContext();
        public ActionResult Index()
        {
            return View(db.Calculators.OrderByDescending(c => c.Id).Take(5).ToList());
        }
        [HttpPost]
        public ActionResult saveToDatabase(string CalculatorExpression, string CalculatorResult)
        {
            var calculator = new Calculator {CalculatorExpression=CalculatorExpression,CalculatorResult=CalculatorResult };
            db.Calculators.Add(calculator);
            db.SaveChanges();
            return PartialView("_CalculatorHistory", db.Calculators.OrderByDescending(c => c.Id).Take(5).ToList());
        }
            

        [HttpPost]
        public ActionResult compute(string input)
        {
            //Regular expression
            string num = @"[\-]?([0-9]{1,}\.?[0-9]*)";  //Match numbers
            string exp1 = @"(?<NUM1>" + num + ")" + @"(?<OP>[\*\/\^])" + @"(?<NUM2>" + num + ")"; //Match multiplication, division, power operation
            string exp2 = @"(?<NUM1>" + num + ")" + @"(?<OP>[\+\-])" + @"(?<NUM2>" + num + ")"; //Matching addition, addition
            //Define declaration regular expression
            Regex isExp1 = new Regex(exp1); //Multiplication, division, power operation
            Regex isExp2 = new Regex(exp2); //Addition, subtraction
            //Create matching objects
            Match mExp1, mExp2;
            //First deal with the multiplication, division, and power operations in the expression
            mExp1 = isExp1.Match(input);
            while (mExp1.Success)
            {
                GroupCollection gc = mExp1.Groups;  //Group match
                decimal num1 = Convert.ToDecimal(gc["NUM1"].Value);   //Take the operand NUM1
                decimal num2 = Convert.ToDecimal(gc["NUM2"].Value);   //Take the operand NUM2
                switch (gc["OP"].Value) //Take the operator OP and judge the operation
                {
                    case "*":
                        num1 *= num2; break;
                    case "/":
                        if (num2 == 0)  //Determine whether the divisor is 0
                        {
                            return Json("DivNumZero", JsonRequestBehavior.AllowGet);//Returns the divisor 0 flag string
                        }
                        else
                        {
                            num1 /= num2;
                            break;
                        }
                }
                input = input.Replace(mExp1.Value, string.Format("{0:f2}", num1)); //Replace the calculation result into the expression
                mExp1 = isExp1.Match(input);    //Re-match multiplication and division
            }
            //Process addition and subtraction
            mExp2 = isExp2.Match(input);
            while (mExp2.Success)
            {
                GroupCollection gc = mExp2.Groups; 
                decimal num1 = Convert.ToDecimal(gc["NUM1"].Value);  
                decimal num2 = Convert.ToDecimal(gc["NUM2"].Value);   
                switch (gc["OP"].Value) 
                {
                    case "+": num1 += num2; break;
                    case "-": num1 -= num2; break;
                }
                input = input.Replace(mExp2.Value, string.Format("{0:f2}", num1));  
                mExp2 = isExp2.Match(input);    //Rematch addition and subtraction
            }
            //Return the result 
            return Json(input,JsonRequestBehavior.AllowGet);
        }

Index

<h2>CalculatorDemo</h2>
@model IEnumerable<CalculatorDemo.Models.Calculator>
<input id="show" />
<button id="ShowCalculatorHistory">CalculatorHistory</button>
<input type="hidden" id="hiddenshow" />
<table id="Calculator" class="table table-bordered">
    <tr><td class="active">delete</td><td class="active">*</td><td class="active">/</td><td class="active">=</td></tr>
    <tr><td>7</td><td>8</td><td>9</td><td class="active">C</td></tr>
    <tr><td>4</td><td>5</td><td>6</td><td class="active">-</td></tr>
    <tr><td>1</td><td>2</td><td>3</td><td class="active">+</td></tr>
    <tr><td>+/-</td><td>0</td><td>.</td><td id="result" class="active">=</td></tr>
</table>
<div id="CalculatorHistory" style="display:none">
    <table id="CalculatorHistoryTable" class="table table-bordered">
        <thead><tr><th>History</th></tr></thead>
        <tbody>
            @foreach (var item in Model)
            {
                <tr><td>@item.CalculatorExpression=@item.CalculatorResult</td></tr>
            }
        </tbody>
    </table>
</div>
@section scripts{
    <script>
        $("#Calculator").on('click', 'td', function (event) {
            $('.success').removeClass('success');
            $(this).addClass('success');
            if ($(this).html() == "C") {
                $("#show").val('');
            } else if ($(this).html() == "delete") {
                $("#show").val($("#show").val().substring(0, ($("#show").val().length - 1)));
            }else if ($(this).html() != "=") {
                if ($(this).html() == "+/-") {
                    $("#show").val($("#show").val() + "-");
                } else{
                    $("#show").val($("#show").val() + $(this).html());
                }
            }
        });
        $('#result').click(function () {
            var calculatestring = $("#show").val();
            $("#hiddenshow").val(calculatestring);
            $.ajax({
                url: "@Url.Action("compute")",
                data: { input: calculatestring},
                type: "POST",
                success: function (data) {
                    $("#show").val(data);
                    saveToDatabase($("#hiddenshow").val(), data);
                    $('.success').removeClass('success');
                }
            })

        });
        function saveToDatabase(calculatorExpression, calculatorResult){
            $.ajax({
                url: "@Url.Action("saveToDatabase")",
                data: { CalculatorExpression: calculatorExpression, CalculatorResult: calculatorResult },
                type: "POST",
                success: function (data) {
                    $("#CalculatorHistory").html(data);
                    CalculatorHistory();
                }
            });
        }
        $('#ShowCalculatorHistory').click(function () {
            if ($("#CalculatorHistory").css('display') == 'none') {
                $("#CalculatorHistory").show();
            } else {
                $("#CalculatorHistory").hide();
            }
        });
        $(function () {
            CalculatorHistory();
        });
        function CalculatorHistory() {
            $("#CalculatorHistoryTable").on('click', 'tr', function (event) {
                $('.success').removeClass('success');
                var currenttd = $(this).find("td");
                $("#show").val(currenttd.html().split("=")[0]);
            });
        }
    </script>
}

_CalculatorHistory

@model IEnumerable<CalculatorDemo.Models.Calculator>
<table id="CalculatorHistoryTable" class="table table-bordered">
    <thead><tr><th>History</th></tr></thead>
    <tbody>
        @foreach (var item in Model)
        {
            <tr><td>@item.CalculatorExpression=@item.CalculatorResult</td></tr>
        }
    </tbody>
</table>

Here is the result.

Best Regards,

YihuiSun

Answer 2

User-462092770 posted

Thank you man, that really will help me :) I will try to mix/adapt my code with yours .... that will save mee a lot of time

I colud provide you with my code if you want. But what i just want to know is  ----> would for example: your calculator work without a Database. OOr is Database the only Solution.