Reformat a JSON file and save as a new file

Question

Reformat a JSON file and save as a new file

I have a lengthy list of one-level JSON data similar to the example below: json-old.json

[
{"stock": "abc", "volume": "45434", "price": "31", "date": "10/12/12"},
{"stock": "abc", "volume": "45435", "price": "30", "date": "10/13/12"},
{"stock": "xyz", "volume": "34465", "price": "14", "date": "10/12/12"},
{"stock": "xyz", "volume": "34434", "price": "14", "date": "10/13/12"},
{"stock": "zzz", "volume": "76755", "price": "65", "date": "10/12/12"},
{"stock": "zzz", "volume": "85646", "price": "67", "date": "10/13/12"}
]

I am looking for a way to transform this file into a new format in another file: json-new.json

[
{ 
   "abc": {
      "10/12/12": { "volume": "45434", "price": "31" },
      "10/13/12": { "volume": "45435", "price": "30" }
   }
},
{
   "xyz": {
      "10/12/12": { "volume": "34465", "price": "14" },
      "10/13/12": { "volume": "34434", "price": "14" }
   }
},
{
   "zzz": {
      "10/12/12": { "volume": "76755", "price": "65" },
      "10/13/12": { "volume": "85646", "price": "67" }
   }
}
]

Essentially, I want to restructure and nest the data based on the 'stock' and 'date' properties.

Are there any libraries available in JavaScript or Node.js that can assist with automating this conversion process? I have numerous files in a folder that need to be transformed into a single file with the desired structure (to facilitate uploading to a database like Firebase).

javascript json node.js

Answer 1

Answer №1

One helpful method to consider is Array.reduce

const data = [
    { "stock": "abc", "volume": "45434", "price": "31", "date": "10/12/12" },
    { "stock": "abc", "volume": "45435", "price": "30", "date": "10/13/12" },
    { "stock": "xyz", "volume": "34465", "price": "14", "date": "10/12/12" },
    { "stock": "xyz", "volume": "34434", "price": "14", "date": "10/13/12" },
    { "stock": "zzz", "volume": "76755", "price": "65", "date": "10/12/12" },
    { "stock": "zzz", "volume": "85646", "price": "67", "date": "10/13/12" }
]

const formattedData = data.reduce((result, current) => {
    const {stock, date, ...rest} = current

    const info = result[stock] || {}
    info[date] = rest
    result[stock] = info

    return result
}, {})

console.log([formattedData])

Answer 2

One helpful method to consider is Array.reduce

const data = [
    { "stock": "abc", "volume": "45434", "price": "31", "date": "10/12/12" },
    { "stock": "abc", "volume": "45435", "price": "30", "date": "10/13/12" },
    { "stock": "xyz", "volume": "34465", "price": "14", "date": "10/12/12" },
    { "stock": "xyz", "volume": "34434", "price": "14", "date": "10/13/12" },
    { "stock": "zzz", "volume": "76755", "price": "65", "date": "10/12/12" },
    { "stock": "zzz", "volume": "85646", "price": "67", "date": "10/13/12" }
]

const formattedData = data.reduce((result, current) => {
    const {stock, date, ...rest} = current

    const info = result[stock] || {}
    info[date] = rest
    result[stock] = info

    return result
}, {})

console.log([formattedData])

Answer 3

Answer №2

To implement a for loop, you can follow the example below:

var data = [
        { "name": "apple", "quantity": "100", "price": "$1", "date": "12/01/2021" },
        { "name": "banana", "quantity": "50", "price": "$0.50", "date": "12/02/2021" },
        { "name": "orange", "quantity": "75", "price": "$0.75", "date": "12/01/2021" }
    ];
    var output = [];
    var results = []
    for (var item in data)
    {
        var fruit=data[item];
        var info = {
            'quantity': fruit.quantity,
            'price': fruit.price
        }
        var inventory = output[fruit.name] || {};
        inventory[fruit.date] = info;
        output[fruit.name] = inventory;
    }
    for (i in output) {
        var newObj = {}
        newObj[i] = output[i];
        results.push(newObj)
    }
    console.log(results);
   // console.log(JSON.stringify(results));

You can now use the JSON format as your new data structure.

Answer 4

To implement a for loop, you can follow the example below:

var data = [
        { "name": "apple", "quantity": "100", "price": "$1", "date": "12/01/2021" },
        { "name": "banana", "quantity": "50", "price": "$0.50", "date": "12/02/2021" },
        { "name": "orange", "quantity": "75", "price": "$0.75", "date": "12/01/2021" }
    ];
    var output = [];
    var results = []
    for (var item in data)
    {
        var fruit=data[item];
        var info = {
            'quantity': fruit.quantity,
            'price': fruit.price
        }
        var inventory = output[fruit.name] || {};
        inventory[fruit.date] = info;
        output[fruit.name] = inventory;
    }
    for (i in output) {
        var newObj = {}
        newObj[i] = output[i];
        results.push(newObj)
    }
    console.log(results);
   // console.log(JSON.stringify(results));

You can now use the JSON format as your new data structure.

Answer 5

Answer №3

This piece of code should get the job done:

const fs = require('fs')

const groupBy = (items, key) => items.reduce(
    (result, item) => ({
      ...result,
      [item[key]]: [
        ...(result[item[key]] || []),
        item,
      ],
    }), 
    {},
);

const inputFileName = process.argv[2]
const outputFileName = process.argv[3]

const jsonData = JSON.parse(fs.readFileSync(inputFileName, 'utf8'));
const groupedStock = groupBy(jsonData,'stock')
const groupedDate = {}
for(stock in groupedStock)
    groupedDate[stock] = groupBy(groupedStock[stock],'date')

const filteredData = {}
for(stock in groupedDate){
    filteredData[stock] = {}
    for (date in groupedDate[stock]) {
        filteredData[stock][date] = {
            price: groupedDate[stock][date][0].price,
            volume: groupedDate[stock][date][0].volume
        }
    }
}

const result = []
for(stock in filteredData)
    result.push({
        [stock]: filteredData[stock]
    })


fs.writeFileSync(outputFileName, JSON.stringify(result,null,2));

To run this program, use

node convert.js json-old.json json-new.json

Answer 6

This piece of code should get the job done:

const fs = require('fs')

const groupBy = (items, key) => items.reduce(
    (result, item) => ({
      ...result,
      [item[key]]: [
        ...(result[item[key]] || []),
        item,
      ],
    }), 
    {},
);

const inputFileName = process.argv[2]
const outputFileName = process.argv[3]

const jsonData = JSON.parse(fs.readFileSync(inputFileName, 'utf8'));
const groupedStock = groupBy(jsonData,'stock')
const groupedDate = {}
for(stock in groupedStock)
    groupedDate[stock] = groupBy(groupedStock[stock],'date')

const filteredData = {}
for(stock in groupedDate){
    filteredData[stock] = {}
    for (date in groupedDate[stock]) {
        filteredData[stock][date] = {
            price: groupedDate[stock][date][0].price,
            volume: groupedDate[stock][date][0].volume
        }
    }
}

const result = []
for(stock in filteredData)
    result.push({
        [stock]: filteredData[stock]
    })


fs.writeFileSync(outputFileName, JSON.stringify(result,null,2));

To run this program, use

node convert.js json-old.json json-new.json

Reformat a JSON file and save as a new file

Answer №1

Answer №2

Answer №3

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