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CSV Writer
Convert objects/arrays into a CSV string or write them into a file.
Prerequisite
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)
.then(() => {
console.log('...Done');
});
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'
});
const records = [
['Bob', 'French, English'],
['Mary', 'English']
];
csvWriter.writeRecords(records)
.then(() => {
console.log('...Done');
});
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());
console.log(csvStringifier.stringifyRecords(records));
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).
A header line will be written to the file only if given as an array of objects.
-
encoding <string>
(optional)
Default: utf8
.
-
append <boolean>
(optional)
Default: false
. When true
, it will append CSV records to the specified file.
If the file doesn't exist, it will create one.
NOTE: A header line will not be written to the file if true
is given.
Returns:
createArrayCsvWriter(params)
Parameters:
- params
<Object>
-
path <string>
Path to a write file
-
header <Array<string>>
(optional)
Array of field titles
-
encoding <string>
(optional)
Default: utf8
.
-
append <boolean>
(optional)
Default: false
. When true
, it will append CSV records to the specified file.
If the file doesn't exist, it will create one.
NOTE: A header line will not be written to the file if true
is given.
Returns:
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:
createObjectCsvStringifier(params)
Parameters:
Returns:
Returns:
ObjectCsvStringifier#stringifyRecords(records)
Parameters:
Returns:
createArrayCsvStringifier(params)
Parameters:
Returns:
Returns:
ArrayCsvStringifier#stringifyRecords(records)
Parameters:
- records
<Array<Array<string>>>
Returns: