transform object to array with lodash

Question

How can I transform a big object to array with lodash?

var obj = {
  22: {name:\"John\", id:22, friends:[5,31,55], works:{books:[],         


        

Answer 1

If you want the key (id in this case) to be a preserved as a property of each array item you can do

const arr = _(obj) //wrap object so that you can chain lodash methods
            .mapValues((value, id)=>_.merge({}, value, {id})) //attach id to object
            .values() //get the values of the result
            .value() //unwrap array of objects

Answer 2

Transforming object to array with plain JavaScript's(ECMAScript-2016) Object.values:

var obj = {
    22: {name:"John", id:22, friends:[5,31,55], works:{books:[], films:[]}},
    12: {name:"Ivan", id:12, friends:[2,44,12], works:{books:[], films:[]}}
}

var values = Object.values(obj)

console.log(values);

If you also want to keep the keys use Object.entries and Array#map like this:

var obj = {
    22: {name:"John", id:22, friends:[5,31,55], works:{books:[], films:[]}},
    12: {name:"Ivan", id:12, friends:[2,44,12], works:{books:[], films:[]}}
}

var values = Object.entries(obj).map(([k, v]) => ({[k]: v}))

console.log(values);

Answer 3

_.toArray(obj);

Outputs as:

[
  {
    "name": "Ivan",
    "id": 12,
    "friends": [
      2,
      44,
      12
    ],
    "works": {
      "books": [],
      "films": []
    }
  },
  {
    "name": "John",
    "id": 22,
    "friends": [
      5,
      31,
      55
    ],
    "works": {
      "books": [],
      "films": []
    }
  }
]"

Answer 4

For me, this worked:

_.map(_.toPairs(data), d => _.fromPairs([d]));

It turns

{"a":"b", "c":"d", "e":"f"} 

into

[{"a":"b"}, {"c":"d"}, {"e":"f"}]

Answer 5

There are quite a few ways to get the result you are after. Lets break them in categories:

ES6 Values only:

Main method for this is Object.values. But using Object.keys and Array.map you could as well get to the expected result:

Object.values(obj)
Object.keys(obj).map(k => obj[k])

var obj = {
  A: {
    name: "John"
  },
  B: {
    name: "Ivan"
  }
}

console.log('Object.values:', Object.values(obj))
console.log('Object.keys:', Object.keys(obj).map(k => obj[k]))

ES6 Key & Value:

Using map and ES6 dynamic/computed properties and destructuring you can retain the key and return an object from the map.

Object.keys(obj).map(k => ({[k]: obj[k]}))
Object.entries(obj).map(([k,v]) => ({[k]:v}))

var obj = {
  A: {
    name: "John"
  },
  B: {
    name: "Ivan"
  }
}

console.log('Object.keys:', Object.keys(obj).map(k => ({
  [k]: obj[k]
})))
console.log('Object.entries:', Object.entries(obj).map(([k, v]) => ({
  [k]: v
})))

Lodash Values only:

The method designed for this is _.values however there are "shortcuts" like _.map and the utility method _.toArray which would also return an array containing only the values from the object. You could also _.map though the _.keys and get the values from the object by using the obj[key] notation.

Note: _.map when passed an object would use its baseMap handler which is basically forEach on the object properties.

_.values(obj)
_.map(obj)
_.toArray(obj)
_.map(_.keys(obj), k => obj[k])

var obj = {
  A: {
    name: "John"
  },
  B: {
    name: "Ivan"
  }
}

console.log('values:', _.values(obj))
console.log('map:', _.map(obj))
console.log('toArray:', _.toArray(obj))
console.log('keys:', _.map(_.keys(obj), k => obj[k]))

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script>

Lodash Key & Value:

// Outputs an array with [[KEY, VALUE]]
_.entries(obj)
_.toPairs(obj)

// Outputs array with objects containing the keys and values
_.map(_.entries(obj), ([k,v]) => ({[k]:v}))
_.map(_.keys(obj), k => ({[k]: obj[k]}))
_.transform(obj, (r,c,k) => r.push({[k]:c}), [])
_.reduce(obj, (r,c,k) => (r.push({[k]:c}), r), [])

var obj = {
  A: {
    name: "John"
  },
  B: {
    name: "Ivan"
  }
}

// Outputs an array with [KEY, VALUE]
console.log('entries:', _.entries(obj))
console.log('toPairs:', _.toPairs(obj))

// Outputs array with objects containing the keys and values
console.log('entries:', _.map(_.entries(obj), ([k, v]) => ({
  [k]: v
})))
console.log('keys:', _.map(_.keys(obj), k => ({
  [k]: obj[k]
})))
console.log('transform:', _.transform(obj, (r, c, k) => r.push({
  [k]: c
}), []))
console.log('reduce:', _.reduce(obj, (r, c, k) => (r.push({
  [k]: c
}), r), []))

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script>

Note that in the above examples ES6 is used (arrow functions and dynamic properties). You can use lodash _.fromPairs and other methods to compose an object if ES6 is an issue.