How to filter in nested array without eliminating array parent in javascript

Question

i'm trying to filter array that the results of value {purchase} id contain in array of {products.transactions.purchase} id. I want to filter by transaction which have same purchase id value.

the data:

var data = [
  {
    "purchase": "5ace99b014a759325776aabb",
    "products":
      [{
        "transactions":
          [{
            "purchase": "5ace99b014a759325776aabb",
            "price": "25"
          },
          {
            "purchase": "5ace99d714a759325776aac4",
            "price": "23"
          }],
        "_id": "5ace995914a759325776aab0",
        "product_name": "Milk",
      },
      {
        "transactions":
          [{
            "purchase": "5ace99b014a759325776aabb",
            "price": "20"
          },
          {
            "purchase": "5ace99d714a759325776aac4",
            "price": "15"
          }],
        "_id": "5ace995c14a759325776aab1",
        "product_name": "Ketchup",
      }]
  },
  {
    "purchase": "5ace99d714a759325776aac4",
    "products":
      [{
        "transactions":
          [{
            "purchase": "5ace99b014a759325776aabb",
            "price": "22"
          },
          {
            "purchase": "5ace99d714a759325776aac4",
            "price": "21"
          }],
        "_id": "5ace995914a759325776aab0",
        "nama_produk": "Milk",
      },
      {
        "transactions": 
        [{
          "purchase": "5ace99b014a759325776aabb",
          "price": "14"
        },
        {
          "purchase": "5ace99d714a759325776aac4",
          "price": "13"
        }],
        "_id": "5ace995c14a759325776aab1",
        "product_name": "Ketchup",
      }]
  }]

i have been tried but only show child array

function filter() {
  let result = []
  let filter = data.filter(a => {
    return a.products.filter(b => {
      return b.transactions.filter(c => {
        if (a.purchase == c.purchase) result.push(c)
      })
    })
  })
  return result
}
console.log(filter())

// output
> Array [Object 
{ purchase: "5ace99b014a759325776aabb", price: "25" }, Object
{ purchase: "5ace99b014a759325776aabb", price: "20" }, Object
{ purchase: "5ace99d714a759325776aac4", price: "21" }, Object
{ purchase: "5ace99d714a759325776aac4", price: "13" }]

how to the output of filtered array like below output:

[{
  "purchase": "5ace99b014a759325776aabb",
  "products":
    [{
      "transactions":
        [{
          "purchase": "5ace99b014a759325776aabb",
          "price": "25"
        }],
      "_id": "5ace995914a759325776aab0",
      "product_name": "Milk",
    },
    {
      "transactions":
        [{
          "purchase": "5ace99b014a759325776aabb",
          "price": "20"
        }],
      "_id": "5ace995c14a759325776aab1",
      "product_name": "Ketchup",
    }]
},
{
  "purchase": "5ace99d714a759325776aac4",
  "products":
    [{
      "transactions":
        [{
          "purchase": "5ace99d714a759325776aac4",
          "price": "21"
        }],
      "_id": "5ace995914a759325776aab0",
      "nama_produk": "Milk",
    },
    {
      "transactions":
        [{
          "purchase": "5ace99d714a759325776aac4",
          "price": "13"
        }],
      "_id": "5ace995c14a759325776aab1",
      "product_name": "Ketchup",
    }]
}]

Thank you.

You only want one transaction? On your expected output, you only removed the 2nd transaction. — Eddie
– Eddie, Commented Apr 13, 2018 at 2:59
no, but want to transaction which have same purchase id value. — Pengguna
– Pengguna, Commented Apr 13, 2018 at 3:02

Eddie · Accepted Answer · 2018-04-13 03:31:50Z

You can use map and filter

let result = data.map(o=>{ //Use map to loop thru the array
    o = Object.assign({},o);   //Clone the object. So any changes will not affect the original array.
    o.products.map(p=>{   //Use map to loop thru the products
        p.transactions = p.transactions.filter(v=>v.purchase === o.purchase);  //Filter the transactions of the products
    });
    return o;
});

Here is a snippet:

var data=[{purchase:"5ace99b014a759325776aabb",products:[{transactions:[{purchase:"5ace99b014a759325776aabb",price:"25"},{purchase:"5ace99d714a759325776aac4",price:"23"}],_id:"5ace995914a759325776aab0",product_name:"Milk"},{transactions:[{purchase:"5ace99b014a759325776aabb",price:"20"},{purchase:"5ace99d714a759325776aac4",price:"15"}],_id:"5ace995c14a759325776aab1",product_name:"Ketchup"}]},{purchase:"5ace99d714a759325776aac4",products:[{transactions:[{purchase:"5ace99b014a759325776aabb",price:"22"},{purchase:"5ace99d714a759325776aac4",price:"21"}],_id:"5ace995914a759325776aab0",nama_produk:"Milk"},{transactions:[{purchase:"5ace99b014a759325776aabb",price:"14"},{purchase:"5ace99d714a759325776aac4",price:"13"}],_id:"5ace995c14a759325776aab1",product_name:"Ketchup"}]}];

let result = data.map(o => {
  o = Object.assign({}, o);
  o.products.map(p => {
    p.transactions = p.transactions.filter(v => v.purchase === o.purchase);
  });
  return o;
});

console.log(result);

Christian Alexander · Accepted Answer · 2018-04-13 03:09:01Z

4

It appears that filter is being used as a forEach here. I have rewritten the filter function to provide the correct output:

function filter() {
  return data.map(dataItem => ({
    ...dataItem,
    products: dataItem.products.map(product => ({
      ...product,
      transactions: product.transactions.filter(
        transaction => transaction.purchase === dataItem.purchase
      )
    }))
  }));
}

The implementation in the question only pushed the child items to a result array.

In Javascript, Array.prorotype.filter is generally used to produce an Array that conditionally includes or exclude items based on the truthiness of the callback, as documented here.

answered Apr 13, 2018 at 3:09

Christian Alexander

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