javascript - 如何展平和合并每个子数组中的嵌套数组

Question

所以我有这个数据:

let data = [
  {
    "purchase_id": 1,
    "product": [
      {
        "name": "A",
        "id": 1,
        "transactions": [
          {
            "price": 5,
            "qty": 2
          },
          {
            "price": 10,
            "qty": 2
          }
        ]
      },
      {
        "name": "B",
        "id": 2,
        "transactions": [
          {
            "price": 3,
            "qty": 4
          }
        ]
      }
    ]
  },
  {
    "purchase_id": 2,
    "product": [
      {
        "name": "C",
        "id": 3,
        "transactions": [
          {
            "price": 5,
            "qty": 2
          }
        ]
      },
      {
        "name": "D",
        "id": 4,
        "transactions": [
          {
            "price": 3,
            "qty": 4
          }
        ]
      }
    ]
  }
]

我想从每个 data.product.transactions 数据中展开数组:

"transactions": [
    {
       "price",
       "qty"
    }
 ]

预期输出是:

[
  {
    "purchase_id": 1,
    "name": "A",
    "id": 1,
    "price": 5,
    "qty": 2
  },
  {
    "purchase_id": 1,
    "name": "A",
    "id": 1,
    "price": 10,
    "qty": 2
  },
  {
    "purchase_id": 1,
    "name": "B",
    "id": 2,
    "price": 3,
    "qty": 4
  },
  {
    "purchase_id": 2,
    "name": "C",
    "id": 3,
    "price": 5,
    "qty": 2
  },
  {
    "purchase_id": 2,
    "name": "D",
    "id": 4,
    "price": 3,
    "qty": 4
  },
]

我尝试过使用对象分配、减少，但我的代码不起作用。谢谢

Answer 1

使用嵌套 Array.map()创建对象，和spread进入Array.concat()展平每个级别的子数组:

const data = [{"purchase_id":1,"product":[{"name":"A","id":1,"transactions":[{"price":5,"qty":2},{"price":10,"qty":2}]},{"name":"B","id":2,"transactions":[{"price":3,"qty":4}]}]},{"purchase_id":2,"product":[{"name":"C","id":3,"transactions":[{"price":5,"qty":2}]},{"name":"D","id":4,"transactions":[{"price":3,"qty":4}]}]}];

const result = [].concat(...data.map(({ purchase_id, product }) => 
  [].concat(...product.map(({ name, id, transactions }) => 
    transactions.map((o) => ({
      purchase_id,
      name,
      id,
      ...o
    })
)))));

console.log(result);

如果你想避免临时子数组和讨人喜欢，请使用嵌套 Array.forEach()调用，并将创建的对象推送到预定义的数组:

const data = [{"purchase_id":1,"product":[{"name":"A","id":1,"transactions":[{"price":5,"qty":2},{"price":10,"qty":2}]},{"name":"B","id":2,"transactions":[{"price":3,"qty":4}]}]},{"purchase_id":2,"product":[{"name":"C","id":3,"transactions":[{"price":5,"qty":2}]},{"name":"D","id":4,"transactions":[{"price":3,"qty":4}]}]}];

const result = [];

data.forEach(({ purchase_id, product }) => 
  product.forEach(({ name, id, transactions }) => 
    transactions.forEach((o) => result.push({
      purchase_id,
      name,
      id,
      ...o
    })
)));

console.log(result);