Lodash / Javascript - how to find unique keys nested inside objects

Question

I'm trying to go through a large object of data, say of the form:

{
 data1: {
     keyA: 'AValue',
     keyB: 'BValue',
     id: 'UniqueID1'
   },
 data2: {
     keyA: 'AValue',
     keyB: 'BValue',
     id: 'UniqueID2'
   },
 data3: {
     keyA: 'AValue',
     keyB: 'BValue',
     id: 'UniqueID1'
   },
 data4: {
     keyA: 'AValue',
     keyB: 'BValue',
     id: 'UniqueID2'
   }
}

Is there a method to go through this object and return to me the unique values for 'id'? E.g I would like to end up with the values

UniqueID1, UniqueID2,

either in an array or an object, it wouldn't matter. Any help on this would be very much appreciated. Thanks.

Nenad Vracar · Accepted Answer · 2017-05-21T17:51:10.047

You can do this with plain js using map() on Object.keys() and Set to return array of unique keys.

var data = {"data1":{"keyA":"AValue","keyB":"BValue","id":"UniqueID1"},"data2":{"keyA":"AValue","keyB":"BValue","id":"UniqueID2"},"data3":{"keyA":"AValue","keyB":"BValue","id":"UniqueID1"},"data4":{"keyA":"AValue","keyB":"BValue","id":"UniqueID2"}}

var uniq = [...new Set(Object.keys(data).map(e => data[e].id))]
console.log(uniq)

Or with Lodash you can use map and then use uniq.

var data = {"data1":{"keyA":"AValue","keyB":"BValue","id":"UniqueID1"},"data2":{"keyA":"AValue","keyB":"BValue","id":"UniqueID2"},"data3":{"keyA":"AValue","keyB":"BValue","id":"UniqueID1"},"data4":{"keyA":"AValue","keyB":"BValue","id":"UniqueID2"}}

var uniq = _.uniq(_.map(data, 'id'))
console.log(uniq)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.15.0/lodash.min.js"></script>

@NenadVracar you can remove `_.values()`, and it would still work — ryeballar, May 21 '17 at 17:49

score 2 · Answer 2 · answered May 21 '17 at 16:17

2

You can do this without lodash using Array.reduce and Set

const uniques = Object.keys(data).reduce((acc,key) => acc.add(data[key].id), new Set())
console.log(uniques)

answered May 21 '17 at 16:17

dashton

2,684
1
18
15

score 1 · Answer 3 · answered May 21 '17 at 16:08

1

since you tagged lodash you can do it like this as array:

var myArray = [
 {
     keyA: 'AValue',
     keyB: 'BValue',
     id: 'UniqueID1'
 },
 {
     keyA: 'AValue',
     keyB: 'BValue',
     id: 'UniqueID2'
 },
 {
     keyA: 'AValue',
     keyB: 'BValue',
     id: 'UniqueID1'
 },
 {
     keyA: 'AValue',
     keyB: 'BValue',
     id: 'UniqueID2'
   }
];

_.map(myArray, 'id');

here is the documentation

answered May 21 '17 at 16:08

ShukiB

76
1
7

yes thanks, and could chain "_.values(data)" to create the array. – Sam Matthews May 21 '17 at 16:17

Lodash / Javascript - how to find unique keys nested inside objects

3 Answers3