Lodash remove duplicates from nested array

Question

Just getting started looking over lodash and stuck trying to figure out how to remove duplicates from arrays within nested objects.

Working with loop:

const _ = require('lodash');

let data = {
    "deviceA": {
        "serviceA": [
            "Foo",
            "Bar",
            "Foo Bar A",
            "Foo Bar A",
            "Foo Bar A"
        ],
        "serviceB": [
            "Foo",
            "Bar",
            "Foo Bar B",
            "Foo Bar B",
            "Foo Bar B"
        ]
    }
}


for (const key in data) {
    for (const key2 in data[key]) {
        data[key][key2] = _.uniqWith(data[key][key2], _.isEqual)
    }
}

console.log(data)

Is it possible using purely lodash to parse a nested object and update an array to remove duplicates without using a for loop?

Nghi Nguyen · Accepted Answer · 2021-03-11 00:16:24Z

2

You can combine uniq and mapValues to achieve it.

let data = {
    "deviceA": {
        "serviceA": [
            "Foo",
            "Bar",
            "Foo Bar A",
            "Foo Bar A",
            "Foo Bar A"
        ],
        "serviceB": [
            "Foo",
            "Bar",
            "Foo Bar B",
            "Foo Bar B",
            "Foo Bar B"
        ]
    },
    "deviceB": {
        "serviceA": [
            "A",
            "A",
            "Foo Bar A",
        ],
        "serviceB": [
            "B",
            "B",
            "Foo Bar B",
        ]
    }
}

const items = _.mapValues(data, (device) => _.mapValues(device, (service) =>_.uniq(service)))
console.log(items)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.21/lodash.min.js"></script>

answered Mar 11, 2021 at 0:16

Nghi Nguyen

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Comments

Owen Kelvin · Accepted Answer · 2021-03-11 00:10:41Z

1

I think you can consider a solution without lodash, below is an example of how this can be implemented natively using pure js.

let data = {
    "deviceA": {
        "serviceA": [
            "Foo",
            "Bar",
            "Foo Bar A",
            "Foo Bar A",
            "Foo Bar A"
        ],
        "serviceB": [
            "Foo",
            "Bar",
            "Foo Bar B",
            "Foo Bar B",
            "Foo Bar B"
        ]
    }
}

const noDup = Object.entries(data).reduce((p, n) => {
  const a = Object.entries(n[1]).reduce((p1, n1) => 
    ({...p1, [n1[0]]: [...new Set(n1[1])]})
  , {})
  return {...p, [n[0]]: a}
}, {})

console.log(noDup)

answered Mar 11, 2021 at 0:10

Owen Kelvin

15.1k11 gold badges51 silver badges86 bronze badges

3 Comments

tron_jones Over a year ago

Accepted the lodash specific one for the use case, but like this pure implementation as well.

Owen Kelvin Over a year ago

Thats okay, Though consider avoiding lodash, You should aim at making your project as small as possible and if a library can be avoided then avoid it

Nghi Nguyen Over a year ago

Yes I saw a lot of question that solve by native javascript. That's is really awesome. But I think that is a trade off between the stable of the code, readable, support functions of lodash with source code size.

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