how to make multiple api calls node.js promises

Question

I'm new to promises and async programming in javascript, and I'm trying to make multiple API calls to google maps places API in node.js then send data to the client once all the data is received. However, I'm getting some kind of a syntax error saying missing ) after argument list. Sorry if I'm asking a stupid question, I just can't seem to figure the issue out. Thanks for the help!

const fetch = require('node-fetch');

module.exports = (app) => {

    app.post('/search-champ', (req, res) => {


        console.log(req);
        let lat = req.body.param.lat; //before: req.query.lat it's wrong

        let long = req.body.param.long;
        console.log(lat);

        const apiId = 'AIzaSyAeEPop5mofzDJhytOEMtxXaGWFqGB4Q3M';
        const urls = [

            'https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=' + lat + ',' + long + '&rankby=distance&type=department_store&key=AIzaSyAeEPop5mofzDJhytOEMtxXaGWFqGB4Q3M',

            'https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=' + lat + ',' + long + '&rankby=distance&type=food&key=AIzaSyAeEPop5mofzDJhytOEMtxXaGWFqGB4Q3M'
        ];


        Promise.all(urls.map(url =>


            fetch(url)
            .then(checkStatus)


            .then(data => {

                console.log(data)
                res.send({
                    data

                });
            })

        }).catch(err => {
            res.redirect('/error');
        });

        function checkStatus(response) {
            if (response.ok) {
                return Promise.resolve(response);
            } else {
                return Promise.reject(new Error(response.statusText));
            }
        }




    })
}

I think you're missing a curly brace on this line (at the end): Promise.all(urls.map(url => — Jordan Kasper
– Jordan Kasper, Commented Oct 23, 2018 at 17:05
You have }).catch(err => { but you need )).catch(err => { - - Also, instead of res.send(data) you need return data;, then actually finish your Promise.all() by putting a .then( ... ) before .catch( ... ). — user5734311
– user5734311, Commented Oct 23, 2018 at 17:07
You also need to insert .then(r => r.json()) after the fetch() btw. — user5734311
– user5734311, Commented Oct 23, 2018 at 17:19
@ronald shirman i'll suggest you to make your code as much cleaner as much you can, it will help you in identification of any unwanted syntax error — Alok Deshwal
– Alok Deshwal, Commented Oct 23, 2018 at 17:26

front_end_dev · Accepted Answer · 2018-10-23 17:19:32Z

1

Fetch in javascript return an response promise object you have to call the json method on it. Change your checkStatus method to this.

function checkStatus(response) {
            if (response.ok) {
                return Promise.resolve(response.json());
            } else {
                return Promise.reject(new Error(response.statusText));
            }
        }

answered Oct 23, 2018 at 17:19

front_end_dev

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3 Comments

user5734311 Over a year ago

1. you have to do this before checking response.ok I assume 2. OP is using node-fetch, an npm package, but it happens to work the same way

front_end_dev Over a year ago

@ChrisG Why there is a need to check before response.ok. Instead of returning the promise object (Promise.resolve and Promise.reject ) we can directly return the values

function checkStatus(response) {             if (response.ok) {                 return response.json();             } else {                 return new Error(response.statusText);             }         }

user5734311 Over a year ago

You're right, .ok is part of the Response returned by fetch. I thought it's a custom field by the OP that's only available in the actual response data.

Bob Fanger · Accepted Answer · 2018-10-23 17:08:53Z

0

The res.send({ data }); is called for every url in the array, this is probably not what you want, to wait for all api calls to complete, place the res.send() in the then() of the Promise.all()

Promise.all(urls.map(url =>
  fetch(url)
  .then(checkStatus)
).then(data => {
  console.log(data)
  res.send({ data });
}).catch(...)

answered Oct 23, 2018 at 17:08

Bob Fanger

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Comments

Alok Deshwal · Accepted Answer · 2018-10-23 18:17:03Z

Working solution:

const fetch = require('node-fetch');
module.exports = (app) => {
    app.post('/search-champ', (req, res) => {
        let lat = req.body.param.lat; //before: req.query.lat it's wrong
        let long = req.body.param.long;
        const apiId = 'AIzaSyAeEPop5mofzDJhytOEMtxXaGWFqGB4Q3M';
        const urls = [
            'https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=' + lat + ',' + long + '&rankby=distance&type=department_store&key=AIzaSyAeEPop5mofzDJhytOEMtxXaGWFqGB4Q3M',
            'https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=' + lat + ',' + long + '&rankby=distance&type=food&key=AIzaSyAeEPop5mofzDJhytOEMtxXaGWFqGB4Q3M'
        ];
        var apiData = urls.map( (url) => {
            return fetch(url).then(checkStatus);
        });
        Promise.all(apiData)
            .then( (data) => {
            res.send({
                data: data
            });
        });

        function checkStatus(response) {
            if (response.ok) {
                return Promise.resolve(response);
            } else {
                return Promise.reject(new Error(response.statusText));
            }
        }
    });
}

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