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.

The following code sample defines a custom function that extends the AsyncFunction class and creates a timeout to simulate the server-side evaluation.

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)");

The following code sample uses the Refresh formula to recalculate formulas.

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);
}