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.

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.

• javascript
• arrays

• You only want one transaction? On your expected output, you only removed the 2nd transaction. – Eddie Commented Apr 13, 2018 at 2:59
• no, but want to transaction which have same purchase id value. – Pengguna Commented Apr 13, 2018 at 3:02
• which property is purchase id value? purchase or _id? – CozyAzure Commented Apr 13, 2018 at 3:06
• yes, purchase, not _id. – Pengguna Commented Apr 13, 2018 at 3:16

2 Answers 2

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);

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.