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 · 2017-05-21 17:51:10Z

4

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>

edited May 21, 2017 at 17:51

answered May 21, 2017 at 16:06

Nenad Vracar

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2 Comments

ryeballar Over a year ago

@NenadVracar you can remove _.values(), and it would still work

Nenad Vracar Over a year ago

@ryeballar Thanks.

dashton · Accepted Answer · 2017-05-21 16:17:37Z

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, 2017 at 16:17

dashton

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Comments

ShukiB · Accepted Answer · 2017-05-21 16:08:52Z

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, 2017 at 16:08

ShukiB

761 silver badge7 bronze badges

1 Comment

Sam Matthews Over a year ago

yes thanks, and could chain "_.values(data)" to create the array.

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