form-data-encoder

Encode FormData content into the multipart/form-data format

Usage

To start the encoding process, you need to create a new Encoder instance with the FormData you want to encode:

import {Readable} from "stream"

import {FormData, File} from "formdata-node"
import {Encoder} from "form-data-encoder"

import fetch from "node-fetch"

const fd = new FormData()

fd.set("greeting", "Hello, World!")
fd.set("file", new File(["On Soviet Moon landscape see binoculars through YOU"], "file.txt"))

const encoder = new Encoder(fd)

const options = {
  method: "post",

  // Set request headers provided the Encoder.
  // The `headers` property has `Content-Type` and `Content-Length` headers.
  headers: encoder.headers,

  // Create a Readable stream from the Encoder.
  // You can omit usage of `Readable.from` for HTTP clients whose support async iterables.
  // The Encoder will yield FormData content portions encoded into the multipart/form-data format as node-fetch consumes the stream.
  body: Readable.from(encoder)
}

const response = await fetch("https://httpbin.org/post", options)

console.log(await response.json())

Encoder support different spec-compatible FormData implementation. Let's try it with formdata-polyfill:

import {Readable} from "stream"

import {Encoder} from "form-data-encoder"
import {FormData, File} from "formdata-polyfill/esm-min.js"

const fd = new FormData()

fd.set("field", "Some value")
fd.set("file", new File(["File content goes here"], "file.txt"))

const encoder = new Encoder(fd)

const options = {
  method: "post",
  headers: encoder.headers,
  body: Readable.from(encoder)
}

await fetch("https://httpbin.org/post", options)

Installation

You can install this package using npm:

npm install form-data-encoder

Or yarn:

yarn add form-data-encoder

Or pnpm:

pnpm add form-data-encoder

API

`class Encoder`

`constructor(form[, boundary]) -> {Encoder}`

{FormDataLike} form - A FormData object to encode. This object must be a spec-compatible FormData implementation.
{string} boundary - An optional boundary string that will be used by the encoder. If there's no boundary string is present, Encoder will generate it automatically.

Creates a multipart/form-data encoder.

`encode() -> {AsyncGenerator<Buffer, void, undefined>}`

Creates a async iterator allowing to perform encoding process by portions.

`[Symbol.asyncIterator]() -> {AsyncGenerator<Buffer, void, undefined>}`

An alias for Encoder#encode() method.