combine values to an array with same id For JSON object

Question

after join operation, I get JSON object with duplicate id values how it is possible to map them with their association property to an array with javascript

{
    "id": 1,
    "name": "doc 1",
    "appointmentTime": "2018-12-28T00:00:43"
},

{
    "id": 2,
    "name": "doc 2",
    "appointmentTime": "2018-12-25T23:00:53"
},
{
    "id": 2,
    "name": "doc 2",
    "appointmentTime": "2018-12-26T23:00:02"
},
{
    "id": 3,
    "name": "doc3",
    "appointmentTime": null
},

I want something like that

{
    "id": 1,
    "name": "doc1",
    "appointmentTime": ["2018-12-28T00:00:43"]
},
{
        "id": 2,
        "name": "doc 2",
        "appointmentTime": ["2018-12-26T23:00:02","2018-12-26T23:00:02"]
    },
    {
        "id": 3,
        "name": "doc3",
        "appointmentTime": null
    },

Duplicate of stackoverflow.com/questions/24302630/…

Barmar
– Barmar

2018-12-21 23:32:11 +00:00
Commented Dec 21, 2018 at 23:32 — Barmar
– Barmar, Commented Dec 21, 2018 at 23:32

Nurbol Alpysbayev · Accepted Answer · 2018-12-21 23:38:27Z

4

You will need reduce function for that:

const src = [{
    "id": 1,
    "name": "doc 1",
    "appointmentTime": "2018-12-28T00:00:43"
},

{
    "id": 2,
    "name": "doc 2",
    "appointmentTime": "2018-12-25T23:00:53"
},
{
    "id": 2,
    "name": "doc 2",
    "appointmentTime": "2018-12-26T23:00:02"
},
{
    "id": 3,
    "name": "doc3",
    "appointmentTime": null
}]

const result = src.reduce((acc, {id, name, appointmentTime}) => {
  const existing = acc.find(i => i.id === id)
  if (existing) { existing.appointmentTime.push(appointmentTime) } 
  else {acc.push({id, name, appointmentTime: [appointmentTime]})}
  
  return acc
}, [])

console.log(result)

I also used destructuring assignment

answered Dec 21, 2018 at 23:38

Nurbol Alpysbayev

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1 Comment

Arenas V. Over a year ago

Thanks, is util. I create some changes for other array call 'formData2'...

var result = formData2.reduce((acc, {name, value}) => {                 var existing = acc.find(i => i.name === name);                 if(existing){                     existing.value = (existing.value + ';' + value);                 }else{                     acc.push({name, value});                 }return acc; }, [])

Mustehssun Iqbal · Accepted Answer · 2018-12-22 01:25:19Z

1

> let mergeDuplicates = (arr, uniqueKey, mergeKey) => {
> let hashMap = {}; arr.forEach(item => {
> 
>     if(hashMap[item[uniqueKey]] == null) { item[mergeKey] = [item[mergeKey]]; hashMap[item[uniqueKey]] = item;  }
>     else { hashMap[item[uniqueKey]][mergeKey].push(item[mergeKey]); }

>     let ansArr = [];
>     for(var key in hashMap){
>        ansArr.push(hashMap[key]);
>     }
>     return ansArr;
> 
> })
>
> }
> myarray = mergeDuplicates(myarray, "id", "appointmentTime");

edited Dec 22, 2018 at 1:25

answered Dec 22, 2018 at 1:20

Mustehssun Iqbal

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1 Comment

Mustehssun Iqbal Over a year ago

This will have O(n) complexity.

Stani B. · Accepted Answer · 2018-12-21 23:57:58Z

i would do it like this:

    //lets say you got your jsonObj already in an Array like:
var myarray = [{
    "id": 1,
    "name": "doc 1",
    "appointmentTime": "2018-12-28T00:00:43"
  },
  {
    "id": 2,
    "name": "doc 2",
    "appointmentTime": "2018-12-25T23:00:53"
  },
  {
    "id": 2,
    "name": "doc 2",
    "appointmentTime": "2018-12-26T23:00:02"
  },
  {
    "id": 3,
    "name": "doc3",
    "appointmentTime": null
  }
];

//just loop through your data and combine it
for (var i = 0; i < myarray.length; i++) {
  //And loop again for duplicate data
  for (var j = i + 1; j < myarray.length; j++) {
    if (myarray[i].id == myarray[j].id) {
      var tmp = myarray[j].appointmentTime;
      myarray[j].appointmentTime = [];
      myarray[j].appointmentTime.push(tmp);
      myarray[j].appointmentTime.push(myarray[i].appointmentTime);

      myarray[i] = {};
    }
  }
}
console.log(myarray);

remove afterwards all empty jsonobj

https://jsfiddle.net/m073qwr6/1/

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