Creating another differently formatted js object from an existing js object

Question

I have a function which is returning a js object in this format

{ _id: { day: 21, month: 10, year: 2020 },
  TOTAL: 9,
  A: 4,
  B: 1,
  C: 1,
  D: 2 }

and I have to format the above one into this format:

{ modalities:
   { TOTAL: { '21-09-2020': 2, '20-10-2020': 1, '21-10-2020': 8 },
     A: { '21-09-2020': 1, '21-10-2020': 4 },
     B: { '21-10-2020': 1 },
     C: { '21-09-2020': 1, '21-10-2020': 1 },
     D: { '20-10-2020': 1, '21-10-2020': 2 } } }

as a beginner, I don't have much experience with formatting and right now I'm thinking to implement this with forEach. Is there any better way to do it in javascript?

This is a bit of a tricky "groupBy" operation. Are you certain you want the dates as keys in final output? It doesn't make it any more difficult to create but standardized key names are easier to work with once you have it transformed — charlietfl
– charlietfl, Commented Oct 26, 2020 at 6:13
Yes, I want this to be specified in that format and I'm not entirely sure how to do it. — Ashish Bairwa
– Ashish Bairwa, Commented Oct 26, 2020 at 6:19

Jagdish Idhate · Accepted Answer · 2020-10-26 07:56:07Z

1

You can use .reduce as below, by iterating over objects and merging them into single object.

Below code will add any dynamic keys as well, except _id, (if you want you can hardcode keys if you want strict schema).

const temp = [{"_id":{"day":21,"month":10,"year":2020},"TOTAL":9,"XR":4,"CT":1,"MR":1,"MG":2},{"_id":{"day":20,"month":10,"year":2020},"TOTAL":1,"XR":0,"CT":0,"MR":0,"MG":1},{"_id":{"day":21,"month":9,"year":2020},"TOTAL":2,"XR":1,"CT":0,"MR":1,"MG":0}];

const result = temp.reduce((res, obj) => {
  const id = `${obj._id.day}-${obj._id.month}-${obj._id.year}`;
  for (let key in obj) {
    if (key === '_id') // Skip _id, as we don't want in resulting object
      continue;
    if(obj[key]){  // As OP output skips 0 valued keys
      res.modalities[key] = res.modalities[key] || {};
      res.modalities[key][id] = obj[key];
   }
  }
  return res;
}, {modalities:{}});

console.log(result)

edited Oct 26, 2020 at 7:56

answered Oct 26, 2020 at 7:00

Jagdish Idhate

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5 Comments

Ashish Bairwa Over a year ago

Oh, so that's how we can use reduce in this condition. Thanks, that's a good one.

Ashish Bairwa Over a year ago

Will you please point out some links where I can get more information around the map and reduce things?

Jagdish Idhate Over a year ago

medium.com/poka-techblog/… this may helpful

Ashish Bairwa Over a year ago

One last question, what if we want to sort the dates accordingly?

Jagdish Idhate Over a year ago

modalities and all inside values are Objects with key value pairs, javascript keys will not be sorted. You have to either convert them to array then come up with example how do you wanna sort this. Ref: stackoverflow.com/questions/1069666/…

Simon · Accepted Answer · 2020-10-26 06:25:18Z

1

let data = [
  {
    "_id": {
      "day": 21,
      "month": 10,
      "year": 2020
    },
    "TOTAL": 9,
    "XR": 4,
    "CT": 1,
    "MR": 1,
    "MG": 2
  },
  {
    "_id": {
      "day": 20,
      "month": 10,
      "year": 2020
    },
    "TOTAL": 1,
    "XR": 0,
    "CT": 0,
    "MR": 0,
    "MG": 1
  },
  {
    "_id": {
      "day": 21,
      "month": 9,
      "year": 2020
    },
    "TOTAL": 2,
    "XR": 1,
    "CT": 0,
    "MR": 1,
    "MG": 0
  }
];

let result = {
    modalities: {
        TOTAL: {},
        XR: {},
        CT: {},
        MR: {},
        MG: {}
    }
};

for (let element of data) {
    let date = element._id.day + '-' + element._id.month + '-' + element._id.year;
    result.modalities.TOTAL[date] = element.TOTAL;
    result.modalities.XR[date] = element.XR;
    result.modalities.CT[date] = element.CT;
    result.modalities.MR[date] = element.MR;
    result.modalities.MG[date] = element.MG;
}

console.log('result: ' + JSON.stringify(result));

sample output

result: {
  "modalities": {
    "TOTAL": {
      "21-10-2020": 9,
      "20-10-2020": 1,
      "21-9-2020": 2
    },
    "XR": {
      "21-10-2020": 4,
      "20-10-2020": 0,
      "21-9-2020": 1
    },
    "CT": {
      "21-10-2020": 1,
      "20-10-2020": 0,
      "21-9-2020": 0
    },
    "MR": {
      "21-10-2020": 1,
      "20-10-2020": 0,
      "21-9-2020": 1
    },
    "MG": {
      "21-10-2020": 2,
      "20-10-2020": 1,
      "21-9-2020": 0
    }
  }
}

answered Oct 26, 2020 at 6:25

Simon

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2 Comments

Ashish Bairwa Over a year ago

It's working, but is there any other workaround other than for and foreach?

Simon Over a year ago

i suppose you can use while loop. or did you want to avoid looping? for loops make the most sense in my opinion

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