Added support for spec-compliant FormData & Blob types;

[DigitalBrainJS]

• supports spec-compliant FormData encoding on Node.js platform (Closes Support other FormData implementations #4610; Closes Using FormData type from Node.js 18 global leads to an error. #5327);
  • respects the boundary value from the content-type header (just in case)
  • prefers the native FormData implementation over form-data package;
• supports Blobs;
• added support for the content-length header when using FromData instance provided by form-data package (Closes Content-Length header is not set even if form-data uses knownLength property  #5275 );

Suggested release: 1.3.0-alpha.1

[jimmywarting]

fyi, i think you should deprecate & then remove the form-data package and switch it out for something more spec compatible. like global FromData, formdata-polyfill or formdata-node

and you should also stop recommending ppl to use form-data and provide some migration plan/documentation

[DigitalBrainJS]

@jimmywarting So far it doesn't make much sense to deprecate the form-data package. Both implementations work well with simple data, while native FormData API doesn't have File interface to represent the FileSystem Blob (form-data supports streams as a payload)
In addition, it seems Blob implementations don't support memory-efficient data streaming, since they store all chunks in RAM.
If this is true, then it casts doubt on the possibility of using this API as the main one for a server environment where huge files can be transferred in a multi-threaded environment.

[jimmywarting]

while native FormData API doesn't have File interface to represent the FileSystem Blob

well, That's true. but all three spec compliant FormData impl. that I know of supports Blob/File look-a-like items.

if you use something like fetch-blob then you can create Blob/File like objects backed up by the filesystem so that nothings needs to be kept in RAM.
node-fetch and got both deprecated form-data also b/c it wasn't spec compatible.

// The default export is sync and use fs.stat to retrieve size & last modified as a blob
import blobFromSync from 'fetch-blob/from.js'
import { File, Blob, blobFrom, blobFromSync, fileFrom, fileFromSync } from 'fetch-blob/from.js'

const fsFile = fileFromSync('./2-GiB-file.bin', 'application/octet-stream')
const fsBlob = await blobFrom('./2-GiB-file.mp4')

// Not a 4 GiB memory snapshot, just holds references
// points to where data is located on the disk
const blob = new Blob([fsFile, fsBlob, 'memory', new Uint8Array(10)])
console.log(blob.size) // ~4 GiB

undici (NodeJS) FormData, as well as formdata-polyfill and formdata-node supports Blob / File look-a-like items.

You can even do something like:

const form = new FormData()

// You can use file-shaped or blob-shaped objects as FormData value instead of creating separate class
form.set("stream", {
  type: "text/plain",
  name: "file.txt",
  size: 1024,
  [Symbol.toStringTag]: "File",
  stream() {
    return getStreamFromSomewhere()
  }
})

This is how both node-fetch and got recommends adding files to FormData.

(formdata-node comes with it's own way of getting a File like object - mostly copied from fetch-blob)

import {fileFromPath} from 'formdata-node/file-from-path'

the only thing this dose is stat-ing the file for getting the file name, size & last modified date. nothing is really held in memory. and nothing is read until you actually start piping the formdata to the network request.

---

form-data haven't been updated in ages and still lacks proper FormData methods such as get(), delete(), has(), entries() and much more.

[jimmywarting]

beside nodejs is also looking into getting a File object represented by the file system. think it's going to be something like fd.getFiile() or something like it.

NodeJS v20 have fs.openAsBlob(path)

[jimmywarting]

And something that you really expect to get out of doing something like request.formData().then(...) is to get out a spec'ed FormData back so that you can iterate over all fields to get all the values.
But i know that you don't currently support parsing a response or a request into a FormData yet.

But if that's something you would add support for then you better have a spec compatible FormData.

with node-fetch and built in fetch you can basically do something like:

app.post('/upload', (req, res) => {
  new Response(req, { headers: req.headers }).formData().then(fd => {
    const file = fd.get('file')
    console.log(file.size)
    file.stream().pipeTo(dest)
  })
})

no extra busboy parser or anything needed at all...