How to parse JSON object to CSV file using json2csv nodejs module

Question

I'm currently learning how to parse a JSON object to a CSV file using the json2csv node module. Have never worked with JSON before, so this is all new to me.

My JSON object is formatted like this:

{
 "car":
      {
          "name":["Audi"],
          "price":["40000"],
          "color":["blue"]
      }
}

And the output CSV file is formatted like this:

"car","name","price","color"
{"name":["Audi"],"price":["40000"],"color":["blue"]},,,

How would I be able to get the CSV output to look like this instead?

name, price, color
"Audi",40000,"blue"

I understand I can call fields directly for just regular JSON data, but I don't understand how it would work under a JSON object.

prajapatijayesh · Accepted Answer · 2019-07-22 17:48:38Z

9

const { Parser } = require('json2csv');

let myCars = {
    "car":
    {
        "name": ["Audi"],
        "price": ["40000"],
        "color": ["blue"]
    }
};

let fields = ["car.name", "car.price", "car.color"];

const parser = new Parser({
    fields,
    unwind: ["car.name", "car.price", "car.color"]
});

const csv = parser.parse(myCars);

console.log('output',csv);

will output to console

edited Jul 22, 2019 at 17:48

answered Jul 22, 2019 at 17:34

prajapatijayesh

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Comments

Guy Gavriely · Accepted Answer · 2013-12-17 06:06:47Z

json2csv only support a flat structure where fields are direct children of the json root.

if you wish to change it, consider cloning the code and do something like the following:

// createColumnContent function changed from original code
var createColumnContent = function(params, str, callback) {
  params.data.forEach(function(data_element) {
    //if null or empty object do nothing
    if (data_element && Object.getOwnPropertyNames(data_element).length > 0) {
      var line = '';
      var eol = os.EOL || '\n';
      params.fields.forEach(function(field_element) {
        // here, instead of direct child, getByPath support multiple subnodes levels
        line += getByPath(data_element, field_element.split('.'), 0) + params.del;
      });
      //remove last delimeter
      line = line.substring(0, line.length - 1);
      line = line.replace(/\\"/g, '""');
      str += eol + line;
    }
  });
  callback(str);
};

var getByPath = function(data_element, path, position) {
  if (data_element.hasOwnProperty(path[position])) {
    if (position === path.length - 1) {
      return JSON.stringify(data_element[path[position]]);
    }
    else {
      return getByPath(data_element[path[position]], path, position + 1)
    }
  }
  else {
    return '';
  }
}

usage:

json2csv({data: json, fields: ['car.name.0', 'car.price.0', 'car.color.0']}, function(err, csv) {
  if (err) console.log(err);
  fs.writeFile('file.csv', csv, function(err) {
    if (err) throw err;
    console.log('file saved');
  });
});

output file content:

"car.name.0","car.price.0","car.color.0"
"Audi","40000","blue"

as a side note, to clone and work with your own version:

git clone https://github.com/zeMirco/json2csv.git

add changes...

to use changed version:

npm install /local/path/to/repo

TomServo · Accepted Answer · 2017-07-19 17:43:59Z

7

You can also direct json2csv to use a sub array within your JSON object by addressing it with .<name> after your JSON object in the data section of json2csv.

In your case, this might look something like:

const json2csv = require('json2csv');
const fs = require('fs');

var json = {
 "car":[
  {
   "name":"Audi",
   "price":"40000",
   "color":"blue"
  }
 ]
};

json2csv({data: json.car, fields: ['name', 'price', 'color']}, function(err, csv) {
  if (err) console.log(err);
  fs.writeFile('cars.csv', csv, function(err) {
    if (err) throw err;
    console.log('cars file saved');
  });
});

edited Jul 19, 2017 at 17:43

TomServo

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answered Jul 19, 2017 at 16:42

Eric Vermeer

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Comments

Kellen · Accepted Answer · 2021-01-22 17:36:02Z

4

I was able to solve this using the parse method and formatting my json data as an array of objects.

const { parse, Parser } = require('json2csv');
const data = [
     {key: value, key2: value2 },
     {key: value3, key2: value4 }
     ];
const fields = ['key', 'key2'];
const csv = parse(data, { fields });

Then do what you need with the csv variable.

answered Jan 22, 2021 at 17:36

Kellen

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Comments

damphat · Accepted Answer · 2013-12-16 22:36:58Z

3

The input is bad format, it should like json2csv document:

var json2csv = require('json2csv');

var json = [
  {
    "car": "Audi",
    "price": 40000,
    "color": "blue"
  }, {
    "car": "BMW",
    "price": 35000,
    "color": "black"
  }, {
    "car": "Porsche",
    "price": 60000,
    "color": "green"
  }
];

json2csv({data: json, fields: ['car', 'price', 'color']}, function(err, csv) {
  if (err) console.log(err);
  fs.writeFile('file.csv', csv, function(err) {
    if (err) throw err;
    console.log('file saved');
  });
});

The content of the "file.csv" should be

car,       price, color
"Audi",    40000, "blue"
"BMW",     35000, "black"
"Porsche", 60000, "green"

answered Dec 16, 2013 at 22:36

damphat

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1 Comment

imthinhvu Over a year ago

Hi, thanks for replying! Could you let me know why the input is bad format? Ultimately, what I'm doing is converting from XML to JSON first, and then JSON to CSV. The XML to JSON input/output will be similar to how I have the original format.

Kauê Gimenes · Accepted Answer · 2020-05-30 22:39:42Z

1

I don't know about you guys, but i like small packages that just work as expected without a lot of extra configuration, try using jsonexport, works really well with objects, arrays, .. and its fast!

Install

npm i --save jsonexport

Usage

const jsonexport = require('jsonexport');
const fs = require('fs');

jsonexport({
 "car":[
  {
   "name":"Audi",
   "price":"40000",
   "color":"blue"
  }
 ]
}, function(err, csv) {
  if (err) return console.error(err);
  fs.writeFile('cars.csv', csv, function(err) {
    if (err) return console.error(err);
    console.log('cars.csv saved');
  });
});

https://github.com/kauegimenes/jsonexport

edited May 30, 2020 at 22:39

answered May 30, 2020 at 22:29

Kauê Gimenes

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Comments

user2688473 · Accepted Answer · 2014-03-07 01:40:51Z

-1

Check out Underscore.js pluck method - if you pass _.pluck(json, 'car') to json2csv's data instead of the original json, you should get what you're looking for.

answered Mar 7, 2014 at 1:40

user2688473

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