multi-part-lite

A multi-part-lite allows you to create multipart/form-data Stream and Buffer, which can be used to submit forms and file uploads to other web applications.

There are no external dependencies, so it as fast and simple as possible.

Supports: Strings, Numbers, Arrays, Streams, Buffers and Vinyl.

Install

$ npm install multi-part-lite --save

Usage

Usage with got as Stream:

const got = require('got');
const Multipart = require('multi-part-lite');
const form = new Multipart();
 
form.append('photo', got.stream('https://avatars1.githubusercontent.com/u/2401029'), { filename: 'image.jpg', contentType: 'image/jpeg' });
form.append('field', 'multi-part test');
 
got.post('127.0.0.1:3000', { headers: form.getHeaders(), body: form.stream() });

Usage with got as Buffer:

const got = require('got');
const Multipart = require('multi-part-lite');
const form = new Multipart();
 
form.append('photo', got.stream('https://avatars1.githubusercontent.com/u/2401029'), { filename: 'image.jpg', contentType: 'image/jpeg' });
form.append('field', 'multi-part test');
 
(async () => {
  const body = await form.buffer();
  got.post('127.0.0.1:3000', { headers: form.getHeaders(false), body });
})()

Usage with http/https as Stream:

const http = require('http');
const https = require('https');
const Multipart = require('multi-part-lite');
const form = new Multipart();
 
form.append('photo', https.request('https://avatars1.githubusercontent.com/u/2401029'), { filename: 'image.jpg', contentType: 'image/jpeg' });
 
form.stream().pipe(http.request({ headers: form.getHeaders(), hostname: '127.0.0.1', port: 3000, method: 'POST' }));

Usage with http/https as Buffer:

const http = require('http');
const https = require('https');
const Multipart = require('multi-part-lite');
const form = new Multipart();
 
form.append('photo', https.request('https://avatars1.githubusercontent.com/u/2401029'), { filename: 'image.jpg', contentType: 'image/jpeg' });
 
(async () => {
  const body = await form.buffer();
  const req = http.request({ headers: form.getHeaders(false), hostname: '127.0.0.1', port: 3000, method: 'POST' });
  req.end(body);
})()

API

new Multipart([options])

Constructor.

Params:

• [options] (Object) - Object with options:
  • [boundary] (String|Number) - Custom boundary for multipart data. Ex: if equal CustomBoundary, boundary will be equal exactly CustomBoundary.
  • [boundaryPrefix] (String|Number) - Custom boundary prefix for multipart data. Ex: if equal CustomBoundary, boundary will be equal something like --CustomBoundary567689371204.
  • [defaults] (Object) - Object with defaults values:
    • [name] (String) - File name which will be used, if filename is not specified in the options of .append method. By default file.
    • [ext] (String) - File extension which will be used, if filename is not specified in the options of .append method. By default bin.
    • [type] (String) - File content-type which will be used, if contentType is not specified in the options of .append method. By default application/octet-stream.

.append(name, value, [options])

Adds a new data to the multipart/form-data stream.

Params:

• name (String|Number) - Field name. Ex: photo.
• value (Mixed) - Value can be String, Number, Array, Buffer, ReadableStream or even Vynil.
• [options] (Object) - Additional options:
  • filename (String) - File name. You should always specify file name with extension, otherwise file.bin will be set. Ex: anonim.jpg.
  • contentType (String) - File content type. You should always specify content-type, otherwise application/octet-stream will be set. Ex: image/jpeg.

If value is an array, append will be called for each value:

form.append('array', [0, [2, 3], 1]);
 
// similar to
 
form.append('array', 0);
form.append('array', 2);
form.append('array', 3);
form.append('array', 1);

Null, false and true will be converted to '0', '0' and '1'. Numbers will be converted to strings also.

Warning: You must specify the correct contentType and filename. This library doesn't validate them. You can use multi-part library which can handle it for you.

.stream()

Returns a multipart/form-data stream.

.buffer()

Returns a Promise with a buffer of the multipart/form-data stream data.

.getBoundary()

Returns the form boundary used in the multipart/form-data stream.

form.getBoundary(); // -> '--MultipartBoundary352840693617'

.getLength()

Returns the length of a buffer of the multipart/form-data stream data.

Should be called after .buffer();

For .stream() it's always 0.

await form.buffer();
form.getLength(); // -> 12345

.getHeaders(chunked = true)

Returns the headers.

If you want to get correct content-length, you should call it after .buffer(). There is no way to know content-length of the .stream(), so it will be always 0.

Params:

• chunked (Boolean) - If false - headers will include content-length header, otherwise there will be transfer-encoding: 'chunked'.

form.getHeaders(); // ->
//{
//  'transfer-encoding': 'chunked',
//  'content-type': 'multipart/form-data; boundary="--MultipartBoundary352840693617"'
//}

With .buffer():

form.getHeaders(false); // ->
//{
//  'content-length': '0',
//  'content-type': 'multipart/form-data; boundary="--MultipartBoundary352840693617"'
//}
 
await form.buffer();
form.getHeaders(false); // ->
//{
//  'content-length': '12345',
//  'content-type': 'multipart/form-data; boundary="--MultipartBoundary352840693617"'
//}

License

The MIT License (MIT)
Copyright (c) 2019 Alexey Bystrov