Combine single array of objects by unique attribute

Question

I have an array of object, which has be combined based on a unique attribute. For example:

[
  { "macId": "123", "input": 30},
  { "macId": "567", "input": 40},
  { "macId": "123", "power": 100},
  { "macId": "567", "power": 250}
]

I want the resultant array of object as the following:

[
  { "macId": "123", "input": 30, "power": 100},
  { "macId": "567", "input": 40 "power": 250}
]

Is this possible with lodash? If not, how can I write a short code for this to do so?

I'm almost sure you can do something with Array.reduce and some algorithm — Nolyurn
– Nolyurn, Commented Aug 24, 2017 at 9:57
Just a reminder @chetanraj. There are multiple answers here which answer your question. I suggest you pick one as the accepted answer so we can mark this as solved. (Or if you don't think this question is solved, maybe you could clarify how the answers misunderstand your question, so that others can try to answer your question with this new information in mind). — jonahe
– jonahe, Commented Aug 24, 2017 at 23:20

jonahe · Accepted Answer · 2017-08-24 10:30:43Z

2

Using lodash I would try groupBy using macId, then using merge to "combine" the objects in the resulting array.

const after = 
  _(before)
    .groupBy('macId')
    .map(group => _.merge(...group))
    .value();

answered Aug 24, 2017 at 10:30

jonahe

5,0101 gold badge17 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

trincot · Accepted Answer · 2017-08-24 10:22:27Z

1

I would suggest using an ES6 Map in combination with Object.assign:

const arr = [
    { "macId": "123", "input": 30},
    { "macId": "567", "input": 40},
    { "macId": "123", "power": 100},
    { "macId": "567", "power": 250}
]

const result = [...arr.reduce((acc, obj) =>
    acc.set(obj.macId, Object.assign(acc.get(obj.macId) || {}, obj)), new Map).values()];

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Aug 24, 2017 at 10:22

trincot

357k38 gold badges282 silver badges338 bronze badges

Comments

boehm_s · Accepted Answer · 2017-08-24 10:11:45Z

You can do the following, with Object#assign and Array#find :

var myMergedArray = arr.reduce((acc = [], val) => {
  if (acc.filter(obj => obj.macId === val.macId).length !== 0) {
    Object.assign(acc.find((el) => el.macId === val.macId), val)
  } else {
    acc.push(val);
  }
  return acc;
}, [])

Snippet :

var arr = [
  { "macId": "123", "input": 30},
  { "macId": "567", "input": 40},
  { "macId": "123", "power": 100},
  { "macId": "567", "power": 250}
]

var myMergedArray = arr.reduce((acc = [], val) => {
  if (acc.filter(obj => obj.macId === val.macId).length !== 0) {
    Object.assign(acc.find((el) => el.macId === val.macId), val)
  } else {
    acc.push(val);
  }
  return acc;
}, [])

console.log(myMergedArray);

Koushik Chatterjee · Accepted Answer · 2017-08-24 10:36:48Z

0

Since you have tagged lodash you can easily group it and map it back (merge using reduce or _.merge) easily.

var arr = [
  { "macId": "123", "input": 30},
  { "macId": "567", "input": 40},
  { "macId": "123", "power": 100},
  { "macId": "567", "power": 250}
]

var unique = _.chain(arr).groupBy('macId').map(v => _.merge(...v)).value();

console.log(unique)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

edited Aug 24, 2017 at 10:36

answered Aug 24, 2017 at 10:28

Koushik Chatterjee

4,1933 gold badges20 silver badges32 bronze badges

Collectives™ on Stack Overflow

Combine single array of objects by unique attribute

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related