对象中的深度收集

Question

我在下面有一个 JSON 对象：{    "JOHN": {        "class": "ABC",        "meta": {            "Math": [                {                    "id": "math_point",                    "name": "Math Point",                    "type": "comparable"                },                {                    "id": "math_switch",                    "name": "Math Switch",                    "type": "switch"                }            ],            "History": [                {                    "id": "history_point",                    "name": "Math Point",                    "type": "comparable"                },                {                    "id": "history_switch",                    "name": "Math Switch",                    "type": "switch"                }            ]        }    },    "BOB": {      "class": "DFE",      "meta": {          "Math": [              {                  "id": "math_point",                  "name": "Math Point",                  "type": "comparable"              },              {                  "id": "math_switch",                  "name": "Math Switch",                  "type": "switch"              }          ],          "Biology": [              {                  "id": "biology_point",                  "name": "Biology Point",                  "type": "comparable"              },              {                  "id": "biology_switch",                  "name": "Biology Switch",                  "type": "switch"              }          ]      }  }}使用 Lodash 或 VanilaJS 的最佳方式返回（唯一id）：[  {      "id": "math_point",      "name": "Math Point",      "type": "comparable"  },  {      "id": "math_switch",      "name": "Math Switch",      "type": "switch"  },  {      "id": "history_point",      "name": "Math Point",      "type": "comparable"  },  {      "id": "history_switch",      "name": "Math Switch",      "type": "switch"  },

Answer 1

您可以使用 提取数组 Object.values。将它们展平为一个数组，然后使用一个 Map，键为id，将其减少为一组唯一的值：

let obj = {"JOHN": {"class": "ABC","meta": {"Math": [{"id": "math_point","name": "Math Point","type": "comparable"},{"id": "math_switch","name": "Math Switch","type": "switch"}],"History": [{"id": "history_point","name": "Math Point","type": "comparable"},{"id": "history_switch","name": "Math Switch","type": "switch"}]}},"BOB": {"class": "DFE","meta": {"Math": [{"id": "math_point","name": "Math Point","type": "comparable"},{"id": "math_switch","name": "Math Switch","type": "switch"}],"Biology": [{"id": "biology_point","name": "Biology Point","type": "comparable"},{"id": "biology_switch","name": "Biology Switch","type": "switch"}]}}};

let arr = Array.from(new Map(

    Object.values(obj)

          .flatMap(({meta}) => Object.values(meta))

          .flat()

          .map(o => [o.id, o])

).values());

console.log(arr);

Answer 2

您首先需要将 JSON 解析为 javascript 对象，然后您可以使用临时对象来保存所有唯一键及其对应的对象。之后，您可以使用Object.values()函数从临时对象中提取对象

const obj = {"JOHN": {"class": "ABC","meta": {"Math": [{"id": "math_point","name": "Math Point","type": "comparable"},{"id": "math_switch","name": "Math Switch","type": "switch"}],"History": [{"id": "history_point","name": "Math Point","type": "comparable"},{"id": "history_switch","name": "Math Switch","type": "switch"}]}},"BOB": {"class": "DFE","meta": {"Math": [{"id": "math_point","name": "Math Point","type": "comparable"},{"id": "math_switch","name": "Math Switch","type": "switch"}],"Biology": [{"id": "biology_point","name": "Biology Point","type": "comparable"},{"id": "biology_switch","name": "Biology Switch","type": "switch"}]}}};

const temp = {};

Object.values(obj).forEach(({meta}) => {

  Object.values(meta).flat().forEach(o => (temp[o.id] = o));

});

const result = Object.values(temp);

console.log(result);

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Answer 3

由于这个问题被标记为 lodash 怎么样只是简单地使用这个：

_.flatMapDeep(input, e => Object.values(e.meta))

它更具可读性。

由于您只对每个元对象的值感兴趣。每个元对象的所有值都是一个数组（值，而不是键），您基本上是在查看这些数组的内容，就是这样。所以只需简单地把它们都拿走，然后用 lodash 压平。

让我们有一个片段：

let input = {"JOHN":{"class":"ABC","meta":{"Math":[{"id":"math_point","name":"Math Point","type":"comparable"},{"id":"math_switch","name":"Math Switch","type":"switch"}],"History":[{"id":"history_point","name":"Math Point","type":"comparable"},{"id":"history_switch","name":"Math Switch","type":"switch"}]}},"BOB":{"class":"DFE","meta":{"Math":[{"id":"math_point","name":"Math Point","type":"comparable"},{"id":"math_switch","name":"Math Switch","type":"switch"}],"Biology":[{"id":"biology_point","name":"Biology Point","type":"comparable"},{"id":"biology_switch","name":"Biology Switch","type":"switch"}]}}},

    res = _.flatMapDeep(input, e => Object.values(e.meta));

    

console.log(res);

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

Answer 4

let arr = Object.values(obj)

let ids = [];

for(let i = 0; i < arr.length; i++){

  for(let j = 0; j < Object.values(arr[i].meta).length; j++){

    for(let k = 0; k < Object.values(arr[i].meta)[j].length; k++){

      ids.push(Object.values(arr[i].meta)[j][k].id)

    }

  }

}

console.log([...new Set(ids)])

这将返回所有唯一 ID