How to flatten and merge nested array from each of child array

Question

So i have this data:

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
          }
        ]
      }
    ]
  }
]

And i want to flatten array from each data.product.transactions data:

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

Expected output is:

[
  {
    "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
  },
]

I have tried to use object assign, reduce but my code doesn't work. Thank you

Add the code that you have tried, it would be more helpful. Also there is no need to paste all of your data just an example will do. — Moti Korets
– Moti Korets, Commented Apr 24, 2018 at 8:22

Ori Drori · Accepted Answer · 2018-04-24 08:31:38Z

1

Use nested Array.map() to create the objects, and spread into Array.concat() to flatten the sub-arrays at each level:

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);

If you want to avoid the temp sub-arrays, and the flattering, use nested Array.forEach() calls, and push the created objects to a predefined array:

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);

edited Apr 24, 2018 at 8:31

answered Apr 24, 2018 at 8:26

Ori Drori

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1 Comment

Pengguna Over a year ago

Thank you for your answers.

Kalamarico · Accepted Answer · 2018-04-24 10:03:40Z

1

var arr = [];
data.forEach(x => {
  x.product.forEach(y => {
    y.transactions.forEach(z => {
      z["name"] = y.name;
      z["id"] = y.id;
      z["purchase_id"] = x.purchase_id;
      arr.push(z);
    });
  })
});
console.log(arr);

edited Apr 24, 2018 at 10:03

Kalamarico

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answered Apr 24, 2018 at 9:34

Rahul Bisht

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