Cannot get promise results with promise.all()

Question

I have mutiple update promises with sequelize and execute them parallely by Promise.all

All I get as Result is this: [[1]]

Here is the Code:

const express = require('express');
const router = express.Router();
const PLZ = require('../models/index').PLZ;
const Zone = require('../models/index').Zone;
const multer = require('multer');
const path = require('path');
const XLSX = require('xlsx');

router.post('/add', function (req, res, next) {
    let zone = {
        name: req.body.name,
        color: req.body.color
    };

    const plzs = req.body.plzs;

    for (let i = 0; i < plzs.length; i++) {
        if (plzs[i].plz.toString() === plzs[i].city && plzs[i].plz.toString() === plzs[i].district) {
            plzs[i].city = null;
            plzs[i].district = null;
        }
        delete plzs[i].checked;
    }

    Zone.create(zone).then((result_zone) => {
        let update_operations = [];
        let zone_plzs = [];

        // associate with plzs and put PLZs to database
        for (let i = 0; i < plzs.length; i++) {
            plzs[i].zone_id = result_zone.dataValues.id;
            zone_plzs.push(plzs[i]);

            update_operations.push(PLZ.update({zone_id: plzs[i].zone_id}, {where: {id: plzs[i].id}}).then((result) => {
                return result
            }));
        }

        Promise.all(update_operations)/*.then((arrayOfArrays) => {
            return [].concat.apply([], arrayOfArrays);
        })*/.then((result) => {
            res.send({status: true, data: {zone: result_zone, plzs: result}})
        }).catch(function (err) {
            return next(err);
        });

    }).catch(function (err) {
        next(err)
    });
});

Does anyone know whats wrong?

Edit: I inserted the whole route to give you more details.

Answer 1

Update function of sequelize returns a number of affected rows (first parameter of result array).

PLZ.update({zone_id: plzs[i].zone_id}, {where: {id: plzs[i].id}}).then((result) => {
    return result
});

So the output of this will be [1] , and then you push this into update_operations , for Promise.All

Promise.All will return the array of results so [[1]] , this is what you will get. So there is nothing wrong in that , you are getting what is right.

---

I think , what you want is returning the result , instead of affected rows , in that case you need to add returning: true , like

PLZ.update(
    {   zone_id: plzs[i].zone_id    }, 
    {   
        where: {id: plzs[i].id} ,
        returning: true, // <--------- HERE
    }
);

NOTE : There is no need of .then((result) => { return result }); in your code . it will work without that also