csv-writer

CSV Writer

Convert objects/arrays into a CSV string or write them into a file.

Prerequisite

• Node version 4 or above

Usage

The example below shows how you can write records defined as the array of objects into a file.

const createCsvWriter = require('csv-writer').createObjectCsvWriter;
const csvWriter = createCsvWriter({
    path: 'path/to/file.csv',
    header: [
        {id: 'name', title: 'NAME'},
        {id: 'lang', title: 'LANGUAGE'},
    ]
});

const records = [
    {name: 'Bob',  lang: 'French, English'},
    {name: 'Mary', lang: 'English'}
];

csvWriter.writeRecords(records)       // returns a promise
    .then(() => {
        console.log('...Done');
    });

// This will produce a file path/to/file.csv with following contents:
//
//   NAME,LANGUAGE
//   Bob,"French, English"
//   Mary,English

You can keep writing records into the same file by calling writeRecords multiple times (but need to wait for the fulfillment of the promise of the previous writeRecords call).

Promise.resolve()
    .then(() => csvWriter.writeRecords(records1))
    .then(() => csvWriter.writeRecords(records2))
    ...

However, if you need to keep writing large data to a certain file, you would want to create node's transform stream and use CsvStringifier, which is explained later, inside it , and pipe the stream into a file write stream.

If you don't want to write a header line, don't give title to header elements and just give field ids as a string.

const createCsvWriter = require('csv-writer').createObjectCsvWriter;
const csvWriter = createCsvWriter({
    path: 'path/to/file.csv',
    header: ['name', 'lang']
});

If each record is defined as an array, use createArrayCsvWriter to get an csvWriter.

const createCsvWriter = require('csv-writer').createArrayCsvWriter;
const csvWriter = createCsvWriter({
    header: ['NAME', 'LANGUAGE'],
    path: 'path/to/file.csv'
});

var records = [
    ['Bob',  'French, English'],
    ['Mary', 'English']
];

csvWriter.writeRecords(records)       // returns a promise
    .then(() => {
        console.log('...Done');
    });

// This will produce a file path/to/file.csv with following contents:
//
//   NAME,LANGUAGE
//   Bob,"French, English"
//   Mary,English

If you just want to get a CSV string but don't want to write into a file, you can use createObjectCsvStringifier (or createArrayCsvStringifier) to get an csvStringifier.

const createCsvStringifier = require('csv-writer').createObjectCsvStringifier;
const csvStringifier = createCsvStringifier({
    header: [
        {id: 'name', title: 'NAME'},
        {id: 'lang', title: 'LANGUAGE'},
    ]
});

const records = [
    {name: 'Bob',  lang: 'French, English'},
    {name: 'Mary', lang: 'English'}
];

console.log(csvStringifier.getHeaderString());
// => 'NAME,LANGUAGE\n'

console.log(csvStringifier.stringifyRecords(records));
// => 'Bob,"French, English"\nMary,English\n'

API

createObjectCsvWriter(params)

Parameters:

• params <Object>

  • path <string>

    Path to a write file

  • header <Array<{id, title}|string>>

    Array of objects (id and title properties) or strings (field ids)

  • encoding <string> (optional)

Returns:

• <CsvWriter>

createArrayCsvWriter(params)

Parameters:

• params <Object>

  • path <string>

    Path to a write file

  • header <Array<string>> (optional)

    Array of field titles

  • encoding <string> (optional)

Returns:

• <CsvWriter>

CsvWriter#writeRecords(records)

Parameters:

• records <Array<Object|Array>>

  Depending on which function was used to create a csvWriter (i.e. createObjectCsvWriter or createArrayCsvWriter), records will be either an array of objects or arrays

Returns:

• <Promise>

createObjectCsvStringifier(params)

Parameters:

• params <Object>

  • header <Array<{id, title}|string>>

    Array of objects (id and title properties) or strings (field ids)

Returns:

• <ObjectCsvStringifier>

ObjectCsvStringifier#getHeaderString()

Returns:

• <string>

ObjectCsvStringifier#stringifyRecords(records)

Parameters:

• records <Array<Object>>

Returns:

• <string>

createArrayCsvStringifier(params)

Parameters:

• params <Object>

  • header <Array<string>> (optional)

    Array of field titles

Returns:

• <ArrayCsvStringifier>

ArrayCsvStringifier#getHeaderString()

Returns:

• <string>

ArrayCsvStringifier#stringifyRecords(records)

Parameters:

• records <Array<Array<string>>>

Returns:

• <string>