按子文档值分组对象 - 调整 Array.reduce 方法（元编程？）

Question

我找到了关于如何使用 reduce 进行分组的明确答案。

Most efficient method to groupby on an array of objects

const array = [ 
  { _id:" 5fbcca92c36b24d99395623d",
    assetData:
     { _id: "5fbcca159ae5f2d8ed792542",
       name: 'House 1',
       numberOfRooms: '1',
       numberOfBathrooms: '2' } },
  { _id: "5fbcca92c36b24d99395623c",
    assetData:
     { _id: "5fbcca159ae5f2d8ed792542",
       name: 'House 1',
       numberOfRooms: '1',
       numberOfBathrooms: '2' } },
  { _id: "5fbccb32c36b24d993956242",
    assetData:
     { _id: "5fbbedcb4decb58513e4ba80",
       name: 'House 2',
       numberOfRooms: '1',
       numberOfBathrooms: '1' } },
  { _id: "5fbccb32c36b24d993956243",
    assetData:
     { _id: "5fbbedcb4decb58513e4ba80",
       name: 'House 2',
       numberOfRooms: '1',
       numberOfBathrooms: '1' } },
 ];
 
const groupBy = function (xs, key) {
  return xs.reduce(function (rv, x) {
    (rv[x[key]] = rv[x[key]] || []).push(x);
    return rv;
  }, {});
};
 
 const test = Object.entries(groupBy(array, "_id"));
 
 console.log(test);

我正在尝试适应，而不是按 _id 排序，而是按 assetData._id 排序。更改 groupBy 函数的 key 参数，不要输出行为。它不接受子文档的值。我什至不知道如何继续我的研究，因为我无法真正理解函数 (rv[x[key]] = rv[x[key]] || []) 这部分的含义。我开始阅读有关 ES6 中的元编程的内容，但我不确定它是否会引导我找到答案。有什么建议吗？

Answer 1

好吧，由于我还没有理论上的答案，所以我尝试以实际的方式解决问题。似乎我无法将字符串 assetData._id 直接传递给 key 参数。也许稍后有人会弹出原因。现在，为了获得我预期的结果，我将密钥拆分为密钥和 subkey，并通过 assetData 与 _id 分开。最终代码为：

const array = [ 
  { _id:" 5fbcca92c36b24d99395623d",
    assetData:
     { _id: "5fbcca159ae5f2d8ed792542",
       name: 'House 1',
       numberOfRooms: '1',
       numberOfBathrooms: '2' } },
  { _id: "5fbcca92c36b24d99395623c",
    assetData:
     { _id: "5fbcca159ae5f2d8ed792542",
       name: 'House 1',
       numberOfRooms: '1',
       numberOfBathrooms: '2' } },
  { _id: "5fbccb32c36b24d993956242",
    assetData:
     { _id: "5fbbedcb4decb58513e4ba80",
       name: 'House 2',
       numberOfRooms: '1',
       numberOfBathrooms: '1' } },
  { _id: "5fbccb32c36b24d993956243",
    assetData:
     { _id: "5fbbedcb4decb58513e4ba80",
       name: 'House 2',
       numberOfRooms: '1',
       numberOfBathrooms: '1' } },
 ];
 
const groupBy = function (xs, key, subkey) {
  return xs.reduce(function (rv, x) {
    (rv[x[key][subkey]] = rv[x[key][subkey]] || []).push(x);
    return rv;
  }, {});
};

const test = Object.entries(groupBy(array, "assetData", "_id"))

console.log(test)

我愿意接受更开明的答案！

按子文档值分组对象 - 调整 Array.reduce 方法（元编程？）

Grouping Objects by subdocument value - Adapting the Array.reduce method (metaprogramming?)

javascript

reduce

metaprogramming