如何合并数组中的重复对象父项？

Question

我想合并数组中的对象，以便具有相同 ID 的对象（它是子对象）可以对 total_price 和 total_quantity 值求和。这是我的数据数组：

var data = [
        {
            "_id": {
                "month": 5,
                "year": 2021
            },
            "total_price": 145111500,
            "total_quantity": 7
        },
        {
            "_id": {
                "month": 6,
                "year": 2021
            },
            "total_price": 98386000,
            "total_quantity": 5
        },
        {
            "_id": {
                "month": 6,
                "year": 2021
            },
            "total_price": 32500000,
            "total_quantity": 3
        }
    ]

我想合并具有重复“_id”的对象。下面是输出结果：

var merge = [
        {
            "_id": {
                "month": 5,
                "year": 2021
            },
            "total_price": 145111500,
            "total_quantity": 7
        },
        {
            "_id": {
                "month": 6,
                "year": 2021
            },
            "total_price": 130886000,
            "total_quantity": 8
        }
    ]

提前致谢。

Answer 1

const data = [
  { "_id": { "month": 5, "year": 2021 }, "total_price": 145111500, "total_quantity": 7 },
  { "_id": { "month": 6, "year": 2021 }, "total_price": 98386000, "total_quantity": 5 },
  { "_id": { "month": 6, "year": 2021 }, "total_price": 32500000, "total_quantity": 3 }
];

const res = [...
  // iterate over the list
  data.reduce((map, item) => {
    // construct key from _id
    const key = `${item._id.month}-${item._id.year}`;
    // get prev map value of key if exists
    const prev = map.get(key);
    // update map, if prev not found, set value as item, or update it with the added values
    map.set(
      key, 
      !prev 
        ? item 
        : { ...item, total_price: prev.total_price + item.total_price, total_quantity: prev.total_quantity + item.total_quantity }
    );
    return map;
  }, new Map)
  // return map values
  .values()
];

console.log(res);

Answer 2

var ids = [];
var merge =  [];
for (let i = 0; i < data.length; i++) {
  obj = data[i];
  let dupId = false;
  for (let j = 0; j < ids.length; j++) {
    if (ids[j]["month"] == obj["_id"]["month"] && ids[j]["year"] == obj["_id"]["year"]) {
      merge[j]["total_price"] += obj["total_price"];
      merge[j]["total_quantity"] += obj["total_quantity"];
      dupId = true;
      break;
    }
  }
  if (!dupId) {
    ids.push(obj["_id"]);
    merge.push(obj);
  }
}

代码将：

声明合并数组并将其初始化为空数组
遍历数据数组中的所有元素
在内部，检查合并数组中元素的重复项
如果找到，请添加总数量和总价格
如果没有找到，添加元素到合并数组

如何合并数组中的重复对象父项？

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