console.log returning pending promise, not actual data

Question

So I have this file:

 'use strict'
import * as moment from "moment";
import { Report} from "./Report";
import { Timeframe} from "./Timeframe";
import { ReportComparison } from "./ReportComparison";

function test(firstFrom: string, firstTo: string, secondFrom: string, secondTo: string) {


    var pastReport = new Report(new Timeframe(moment(firstFrom), moment(firstTo)));
    var laterReport = new Report(new Timeframe(moment(secondFrom), moment(secondTo)));

    var reportComparison

    function getData(pastReport: Report, laterReport: Report) {

        var later = function() {
            return new Promise((resolve, reject) => {
                laterReport.fetchData(data => resolve(data));
            });
        };

        var past = function() {
            return new Promise((resolve, reject) => {
                pastReport.fetchData(data => resolve(data));
            });
        };

        return Promise.all([later(), past()]).then(() => {
            laterReport.sort();
            reportComparison = new ReportComparison(pastReport, laterReport);

            return {
                pastReport: {
                    projects: reportComparison.pastReport.projects,
                    timeFrame: reportComparison.pastReport.timeframe,
                    totalAutomatedRuns: reportComparison.pastReport.totalAutomatedRuns,
                    totalManualRuns: reportComparison.pastReport.totalManualRuns

                },
                laterReport: {
                    projects: reportComparison.laterReport.projects,
                    timeFrame: reportComparison.laterReport.timeframe,
                    totalAutomatedRuns: reportComparison.laterReport.totalAutomatedRuns,
                    totalManualRuns: reportComparison.laterReport.totalManualRuns
                },
                trends: reportComparison.trends
            }

        });

    }

    return getData(pastReport, laterReport).then((res) => {
        return res;
    });

}



console.log(test("20170707", "20170707", "20170710", "20170710"))

Right now, the console.log returns Promise { <pending> } and not the actual value I want returned (the JSON object). Am I approaching this asynchronous code correctly? What solution could I use to return the JSON as a value, not a pending promise.

[Drop the pointless `.then(res => res)`](https://stackoverflow.com/q/41089122/1048572) — Bergi, Jul 20 '17 at 12:46
@Bergi FWIW there was an extra `console.log` in there originally - it was edited out for clarity — James Thorpe, Jul 20 '17 at 12:48

Yash Ganatra · Answer 1 · 2017-07-21T03:19:52.153

4

Yes, You will get promise only as you are returning promise from here

return getData(pastReport, laterReport).then((res) => {
    return res; //Do callback here...
});

This is your main return I mean return value of test function and you have returned promise only and note that what you have returned from then it will be returned in that function only so it will not reflect in test's return value. If you don't want to change your code you can use callback

or change it to

return getData(pastReport, laterReport)

and make your test call like this

test(...).then((res)=>{ 
})
Or like this
var a = await test(...)
then test will return data.

edited Jul 21 '17 at 03:19

answered Jul 20 '17 at 12:47

Yash Ganatra

468
2
12

This doesn't actually solve my problem. I want `test` to actually be the json object. Your solution just uses `then` to keep piping the information, never returning it – Adam Siwiec Jul 20 '17 at 12:59
your get data will return it right?? – Yash Ganatra Jul 20 '17 at 13:01
I am returning promise by this call `return getData(pastReport, laterReport)` and then will fetch the json object so your json object will be in res – Yash Ganatra Jul 20 '17 at 13:02
@adamSiwiec yes it does, you need to learn how to work with promises. The data you want to return isn't available until the promise is fulfilled. – Jul 20 '17 at 13:13
Yes, I understand @YashGanatra, but is there a way that test can hold that value and not res? That is my question. – Adam Siwiec Jul 20 '17 at 13:17
use callback as I said – Yash Ganatra Jul 20 '17 at 13:20
Or if you dont want to use then you can use await. I have edited my answer @adamSiwiec – Yash Ganatra Jul 21 '17 at 03:17

JSON Derulo · Answer 2 · 2017-07-20T13:02:28.820

3

The method test indeed returns a promise. To access the data, call the .then() function.

test("20170707", "20170707", "20170710", "20170710")
    .then((response) => {
         console.log(response);
    });

edited Jul 20 '17 at 13:02

answered Jul 20 '17 at 12:42

JSON Derulo

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console.log returning pending promise, not actual data

2 Answers2