lodash .groupBy 사용.

lodash .groupBy 사용. 그룹화 된 출력을 위해 자신의 키를 추가하는 방법은 무엇입니까?

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API에서 반환 된이 샘플 데이터가 있습니다.

Lodash를 사용 _.groupBy하여 데이터를 더 잘 사용할 수있는 개체로 변환하고 있습니다. 반환 된 원시 데이터는 다음과 같습니다.

[
    {
        "name": "jim",
        "color": "blue",
        "age": "22"
    },
    {
        "name": "Sam",
        "color": "blue",
        "age": "33"
    },
    {
        "name": "eddie",
        "color": "green",
        "age": "77"
    }
]

_.groupBy함수가 다음과 같은 객체를 반환하기를 원합니다 .

[
    {
        color: "blue",
        users: [
            {
                "name": "jim",
                "color": "blue",
                "age": "22"
            },
            {
                "name": "Sam",
                "color": "blue",
                "age": "33"
            }
        ]
    },
    {
        color: "green",
        users: [
            {
                "name": "eddie",
                "color": "green",
                "age": "77"
            }
        ]
    }
]

현재 나는

_.groupBy(a, function(b) { return b.color})

이것은 이것을 반환하고 있습니다.

{blue: [{..}], green: [{...}]}

그룹화는 정확하지만 원하는 키 ( color, users) 를 추가하고 싶습니다 . 이것이 가능 _.groupBy합니까? 또는 다른 LoDash유틸리티?

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Lodash 4.x에서 이렇게 할 수 있습니다.

var data = [{
  "name": "jim",
  "color": "blue",
  "age": "22"
}, {
  "name": "Sam",
  "color": "blue",
  "age": "33"
}, {
  "name": "eddie",
  "color": "green",
  "age": "77"
}];

console.log(
  _.chain(data)
    // Group the elements of Array based on `color` property
    .groupBy("color")
    // `key` is group's name (color), `value` is the array of objects
    .map((value, key) => ({ color: key, users: value }))
    .value()
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

---

원래 답변

var result = _.chain(data)
    .groupBy("color")
    .pairs()
    .map(function(currentItem) {
        return _.object(_.zip(["color", "users"], currentItem));
    })
    .value();
console.log(result);

온라인 데모

참고 : Lodash 4.0 이상에서는 .pairs기능의 이름이_.toPairs()

---

이렇게 간단하지 않나요?

var result = _(data)
            .groupBy(x => x.color)
            .map((value, key) => ({color: key, users: value}))
            .value();

---

또 다른 방법

_.chain(data)
    .groupBy('color')
    .map((users, color) => ({ users, color }))
    .value();

---

Highest voted answer uses Lodash _.chain function which is considered a bad practice now "Why using _.chain is a mistake."

Here is a fewliner that approaches the problem from functional programming perspective:

import tap from "lodash/fp/tap";
import flow from "lodash/fp/flow";
import groupBy from "lodash/fp/groupBy";

const map = require('lodash/fp/map').convert({ 'cap': false });

const result = flow(
      groupBy('color'),
      map((users, color) => ({color, users})),
      tap(console.log)
    )(input)

Where input is an array that you want to convert.

---

Thanks @thefourtheye, your code greatly helped. I created a generic function from your solution using the version 4.5.0 of Lodash.

function groupBy(dataToGroupOn, fieldNameToGroupOn, fieldNameForGroupName, fieldNameForChildren) {
            var result = _.chain(dataToGroupOn)
             .groupBy(fieldNameToGroupOn)
             .toPairs()
             .map(function (currentItem) {
                 return _.zipObject([fieldNameForGroupName, fieldNameForChildren], currentItem);
             })
             .value();
            return result;
        }

To use it:

var result = groupBy(data, 'color', 'colorId', 'users');

Here is the updated fiddler;

https://jsfiddle.net/sc2L9dby/

---

Here is an updated version using lodash 4 and ES6

const result = _.chain(data)
    .groupBy("color")
    .toPairs()
    .map(pair => _.zipObject(['color', 'users'], pair))
    .value();

---

I would suggest a different approach, using my own library you could do this in a few lines:

var groupMe = sequence(
  groupBy(pluck('color')),
  forOwn(function(acc, k, v) {
    acc.push({colors: k, users: v});
    return acc;
  },[])
);

var result = groupMe(collection);

This would a be a bit difficult with lodash or Underscore because the arguments are in the opposite order order, so you'd have to use _.partial a lot.

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Example groupBy and sum of a column using Lodash 4.17.4

   var data = [{
                "name": "jim",
                "color": "blue",
                "amount": 22
                }, {
                "name": "Sam",
                "color": "blue",
                "amount": 33
                }, {
               "name": "eddie",
               "color": "green",
               "amount": 77
              }];

      var result = _(data)
                   .groupBy(x => x.color)
                   .map((value, key) => 
                   ({color: key,
                    totalamount: _.sumBy(value,'amount'),
                    users: value})).value();

                    console.log(result);

---

In 2017 do so

_.chain(data)
  .groupBy("color")
  .toPairs()
  .map(item => _.zipObject(["color", "users"], item))
  .value();

참고URL : https://stackoverflow.com/questions/23600897/using-lodash-groupby-how-to-add-your-own-keys-for-grouped-output