How to push a new element to all objects in an array?

Question

Hello guys I am trying to push a new element to all the objects in an array but seem to not update.

Any idea what am I doing wrong in here?

So this is my object which contain the instalments array.

{ _id: 5cf7d4fcc9c5846a69b48d41,
  offer: 5cf7d4fcc9c5846a69b48d40,
  instalments:
   [ { paid: false,
       _id: 5cf7d4fcc9c5846a69b48d44,
       description: 'Some deacription about yhis instalment',
       instalmentAmount: 100000,
       dueTo: 2019-06-06T23:00:00.000Z },
     { paid: false,
       _id: 5cf7d4fcc9c5846a69b48d43,
       description: 'Some deacription about yhis instalment',
       instalmentAmount: 100000,
       dueTo: 2019-06-13T23:00:00.000Z },
     { paid: false,
       _id: 5cf7d4fcc9c5846a69b48d42,
       description: 'Some deacription about yhis instalment',
       instalmentAmount: 91152,
       dueTo: 2019-06-20T23:00:00.000Z } ],
  user: 5cf53a1a8481923f72939940,
  createdAt: 2019-06-05T14:43:08.706Z,
  updatedAt: 2019-06-05T14:43:08.706Z,
  __v: 0 }

What I want to do is to add offer to all instalments objects

The way I am trying to do this is as follow.

instalmentsGroup is the object above then I access instalments and map

const instalments = await instalmentsGroup.instalments.map(
  instalment =>
    Object.assign({}, instalment, { offer: instalmentsGroup.offer })
);

loop through and then for each you add this ?-

axel axel
– axel axel

2019-06-05 15:03:18 +00:00
Commented Jun 5, 2019 at 15:03 — axel axel
– axel axel, Commented Jun 5, 2019 at 15:03
Why you use await? Without await it works as you expected.

Mykola Prymak
– Mykola Prymak

2019-06-05 15:06:11 +00:00
Commented Jun 5, 2019 at 15:06 — Mykola Prymak
– Mykola Prymak, Commented Jun 5, 2019 at 15:06

Nick Parsons · Accepted Answer · 2019-06-05 15:18:11Z

Your issue is with await. There is no need for await as .map does not return a Promise, and so it is not asynchronous.

If you want to edit your object in-place you can use .forEach which would loop through each object in your instalments array and add the order property to it.

See example below:

const obj = {
  _id: "5cf7d4fcc9c5846a69b48d41",
  offer: "5cf7d4fcc9c5846a69b48d40",
  instalments: [{
      paid: false,
      _id: "5cf7d4fcc9c5846a69b48d44",
      description: 'Some deacription about yhis instalment',
      instalmentAmount: 100000,
      dueTo: "2019 - 06 - 06 T23: 00: 00.000 Z"
    },
    {
      paid: false,
      _id: "5cf7d4fcc9c5846a69b48d43",
      description: 'Some deacription about yhis instalment',
      instalmentAmount: 100000,
      dueTo: "2019 - 06 - 13 T23: 00: 00.000 Z"
    },
    {
      paid: false,
      _id: "5cf7d4fcc9c5846a69b48d42",
      description: 'Some deacription about yhis instalment',
      instalmentAmount: 91152,
      dueTo: "2019 - 06 - 20 T23: 00: 00.000 Z"
    }
  ],
  user: "5cf53a1a8481923f72939940",
  createdAt: "2019 - 06 - 05 T14: 43: 08.706 Z",
  updatedAt: "2019 - 06 - 05 T14: 43: 08.706 Z",
  __v: 0
}

const offer = obj.offer;
obj.instalments.forEach(instalment => {
  instalment.offer = offer;
});

console.log(obj.instalments);

Alternatively, you could use .map() like you have to map each object to itself, with an additional offer property which you can get from the original object. Just make sure to remove await. This approach will create a new altered array (and won't modify the original object)

See example below:

const obj = {
  _id: "5cf7d4fcc9c5846a69b48d41",
  offer: "5cf7d4fcc9c5846a69b48d40",
  instalments: [{
      paid: false,
      _id: "5cf7d4fcc9c5846a69b48d44",
      description: 'Some deacription about yhis instalment',
      instalmentAmount: 100000,
      dueTo: "2019 - 06 - 06 T23: 00: 00.000 Z"
    },
    {
      paid: false,
      _id: "5cf7d4fcc9c5846a69b48d43",
      description: 'Some deacription about yhis instalment',
      instalmentAmount: 100000,
      dueTo: "2019 - 06 - 13 T23: 00: 00.000 Z"
    },
    {
      paid: false,
      _id: "5cf7d4fcc9c5846a69b48d42",
      description: 'Some deacription about yhis instalment',
      instalmentAmount: 91152,
      dueTo: "2019 - 06 - 20 T23: 00: 00.000 Z"
    }
  ],
  user: "5cf53a1a8481923f72939940",
  createdAt: "2019 - 06 - 05 T14: 43: 08.706 Z",
  updatedAt: "2019 - 06 - 05 T14: 43: 08.706 Z",
  __v: 0
}

const offer = obj.offer;
const instalments = obj.instalments.map(instalment => ({...instalment, offer}));

console.log(obj.instalments);

Antonio Pangallo · Accepted Answer · 2019-06-05 15:12:49Z

1

Another solution without mutating the object might be:

function addOfferToInstalments(obj) {
  let output = { ...obj };
  const offer = output.offer;
  output.instalments = obj.instalments.map(instalment => ({ ...instalment, offer }));
  return output;
}

answered Jun 5, 2019 at 15:12

Antonio Pangallo

2302 silver badges5 bronze badges

Comments

Meet Zaveri · Accepted Answer · 2019-06-05 15:10:31Z

0

If you want updated array of instalments only, then assign an extra property through map method

const updatedInstallments = instalmentsGroup.instalments.map(obj => {
    obj.offer = instalmentsGroup.offer;
    return obj;
})

Also there is no need of async/await as map does not return a promise.

edited Jun 5, 2019 at 15:10

answered Jun 5, 2019 at 15:05

Meet Zaveri

3,0671 gold badge27 silver badges36 bronze badges

2 Comments

Mykola Prymak Over a year ago

Markus had error in his code with await. The rest of code is good.

Meet Zaveri Over a year ago

Yes, it's of no use there.

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