如何在对象数组中“展开”子数组

好吧,这是个挑战!我有一个工作解决方案,涵盖所有我能想到的情况,但请让我知道,如果有我错过的情况。

我的基本方法从最后开始,我知道我会用 _.zipObject 创建结果对象。从那里开始,这只是一个让其他物业与必要的 key3 键3 有自己的副本。接下来,我将它们链接起来并创建对象。最后,我过滤掉所有不必要的对象副本。

undefined 元素 . 我认为这是一个不太可能的情况,因此没有试图解决。

可理解的版本:

const objects = [{
    "key1": "value1",
    "key2": "value2",
    "key3": ["value3", "value4"]
},
{
    "key1": "value5",
    "key2": "value6",
    "key3": ["value7"]
}];

// Get other key names
const otherKeys = _.without(_.keys(objects[0]), "key3");
// Get values without key3
const otherValues = _.map(_.map(objects, _.partialRight(_.omit, "key3")), _.values);
// Get just key3 values
const onlyKey3 = _.map(objects, "key3");

// Generate dummy range of needed length
const maxLengthKey3 = _.max(_.map(onlyKey3, "length"));
const dummyRange = _.range(maxLengthKey3);

// Grow all arrays to needed length
const newOtherValues = _.flatten(_.map(dummyRange, _.partial(_.identity, otherValues)), true);
const newKey3 = _.flatten(_.map(dummyRange, _.partial(_.map, onlyKey3)));

const pairedValues = _.map(_.zip(newOtherValues, newKey3), _.flatten);
const resultObjects = _.map(pairedValues, _.partial(_.zipObject, _.union(otherKeys, ["key3"])));

// Filter out unnecessary objects
const result = _.filter(resultObjects, "key3");

一字排开:

const objects = [{
    "key1": "value1",
    "key2": "value2",
    "key3": ["value3", "value4"]
},
{
    "key1": "value5",
    "key2": "value6",
    "key3": ["value7"]
}];
// One line
const result = _.filter(_.map(_.map(_.zip(_.flatten(_.map(_.range(_.max(_.map(_.map(objects, "key3"), "length"))), _.partial(_.identity, _.map(_.map(objects, _.partialRight(_.omit, "key3")), _.values))), true), _.flatten(_.map(_.range(_.max(_.map(_.map(objects, "key3"), "length"))), _.partial(_.map, _.map(objects, "key3"))))), _.flatten), _.partial(_.zipObject, _.union(_.without(_.keys(objects[0]), "key3"), ["key3"]))), "key3");

性能:

我认为对于一个大的初始数组或者一个大的长度 键3 . 对于单行版本我特别不寒而栗。如果有人抱怨,我会指出这是由于执行环境的限制造成的。

在浏览器中通过 https://npm.runkit.com/lodash ,使用 var _ = require('lodash@2.4.2');

let array = [{
    "key1": "value1",
    "key2": "value2",
    "key3": ["value3", "value4"]
}, {
    "key1": "value5",
    "key2": "value6",
    "key3": ["value7", "value8"]
}, ]

const result = array.reduce((final, item) => {
    for (let i = 0; i < item.key3.length; i++) {
        final.push(Object.assign({}, item, {
            "key3": item.key3[i]
        }))
    }
    return final;
}, []);

console.log(result);

如果你用洛达斯,我想相当于:

const _ = require('lodash')
const result = _.reduce(array, (final, item) => {
    _.forEach(item.key3, (key3Val) => {
        final.push(Object.assign({}, item, {
            "key3": key3Val
        }))
    })
    return final;
}, []);