SpreadJS Documentation
Using Asynchronous Functions
SpreadJS Documentation > Developer's Guide > Managing the User Interface > Using Formulas > Using Asynchronous Functions

You can evaluate a function on the server side with the AsyncFunction and AsyncEvaluateContext classes. You can use the AsyncFunctionEvaluateMode class to specify how the functions are evaluated.

Using Code

This example defines a custom function that extends the AsyncFunction class and creates a timeout to simulate the server side evaluate.

JavaScript
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var asum = function () {}
//Define a class "ASUM" that extends AsyncFunction
asum.prototype = new GC.Spread.CalcEngine.Functions.AsyncFunction("ASUM", 1, 255);
//Set default value to "Loading..."
asum.prototype.defaultValue = function () { return "Loading..."; };
//Override the evaluateAsync function
asum.prototype.evaluateAsync = function (context) {
var args = arguments;
//Use a timeout to simulate the server side evaluate or use an ajax post
    setTimeout(function () {
//Evaluation logic
        var result = 0;
        for (var i = 0; i < args.length; i++) {
            result += args[i];
        }
        result *= 2;
//Set the async evaluate result to CalcEngine
        context.setAsyncResult(result);
    }, 2000);
}
//Or use Ajax post
/$.ajax({
    //url: '@Url.Action("ASUM", "Home")',
    //type: "POST",
    //data: JSON.stringify(args),
    //contentType: "application/json,charset=UTF-8",
    //success: function (data) {
    //context.SetAsyncResult(data.result);
    //}
//});
//Add the ASUM function to spread and set the formula
activeSheet.addCustomFunction(new asum());
activeSheet.setValue(0, 0, 5);
activeSheet.setValue(0, 1, 15);
activeSheet.setFormula(1, 1, "ASUM(A1,B1)");

This example uses the Refresh formula to recalculate formulas.

JavaScript
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<!DOCTYPE html>
<html>
<head>
    <title>SpreadJS</title>
<link href="./css/gc.spread.sheets.12.0.0.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" src="./scripts/gc.spread.sheets.all.12.0.0.min.js"></script>
<!--jQuery References-->
<script src="http://code.jquery.com/jquery-2.0.2.js" type="text/javascript"></script>

  <script type="text/javascript">
                                window.onload = function(){
            var spread = new GC.Spread.Sheets.Workbook(document.getElementById("ss"),{sheetCount:3});                                          
            var sheet = spread.getActiveSheet();

            var GetNumberFromServer = function () {
            }
            GetNumberFromServer.prototype = new GC.Spread.CalcEngine.Functions.AsyncFunction("GETNUMBERFROMSERVER", 2, 2);
            GetNumberFromServer.prototype.evaluate = function (context, arg1, arg2) {
                var self = this;
                $.get('http://xa-tools-shdev/asyncfunction/api/values/' + (arg1 || 1), function (value) {
                    context.setAsyncResult(value);
                });
            }

            GC.Spread.CalcEngine.Functions.defineGlobalCustomFunction("GETNUMBERFROMSERVER", new GetNumberFromServer());
            sheet.setValue(0, 0, 'ChangeValue');
            sheet.setValue(0, 1, 'Formula');
            sheet.setValue(0, 2, 'Result');
            sheet.setValue(0, 3, 'Comments');
            sheet.setValue(1, 3, 'On A2 changed');
            sheet.setValue(2, 3, 'On A2 changed');
            sheet.setValue(3, 3, 'Evaluate once');
            sheet.setValue(4, 3, 'Every 2 seconds');
            sheet.setValue(1, 0, 1);
            sheet.setValue(1, 1, '=GetNumberFromServer(A2)');
            sheet.setValue(2, 1, '=Refresh(GetNumberFromServer(A2), 0)');
            sheet.setValue(3, 1, '=Refresh(GetNumberFromServer(A2), 1)');
            sheet.setValue(4, 1, '=Refresh(GetNumberFromServer(A2), 2, 2000)');
            sheet.setFormula(1, 2, '=GetNumberFromServer(A2)');
            sheet.setFormula(2, 2, '=Refresh(GetNumberFromServer(A2), 0)');
            sheet.setFormula(3, 2, '=Refresh(GetNumberFromServer(A2), 1)');
            sheet.setFormula(4, 2, '=Refresh(GetNumberFromServer(A2), 2, 2000)');
            sheet.setColumnWidth(0, 100);
            sheet.setColumnWidth(1, 300);
            sheet.setColumnWidth(2, 200);
            sheet.setColumnWidth(3, 200);
            sheet.setValue(7, 1, "=Refresh(now(), 2, 1000)");
            sheet.setValue(7, 3, "Every 1 seconds");
            sheet.setFormula(7, 2, "=Refresh(now(), 2, 1000)");

            var GetTimeFromServer = function () {
            }
            GetTimeFromServer.prototype = new GC.Spread.CalcEngine.Functions.AsyncFunction("GETTIMEFROMSERVER", 2, 2);
            GetTimeFromServer.prototype.evaluate = function (context) {
                $.get('http://xa-tools-shdev/asyncfunction/api/time/', function (value) {
                    context.setAsyncResult(value);
                });
            }
            GetTimeFromServer.prototype.evaluateMode = function () {
                return 2;
            };
            GetTimeFromServer.prototype.interval = function () {
                return 1000;
            };

            GC.Spread.CalcEngine.Functions.defineGlobalCustomFunction("GETTIMEFROMSERVER", new GetTimeFromServer());
            sheet.setValue(10, 1, "=GetTimeFromServer()");
            sheet.setValue(10, 3, "Every 1 seconds");
            sheet.setFormula(10, 2, "=GetTimeFromServer()");
            sheet.getCell(10, 2).hAlign(GC.Spread.Sheets.HorizontalAlign.right);
}
</script>
</head>
<body>
    <div id="ss" style="width:100%;height:500px;border:1px solid gray"></div>
</body>
</html>
See Also

Formula Reference

REFRESH

 

 

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