fix(Body): Discourage form-data and buffer()

[jimmywarting]

Purpose

• We do serialize spec compatible FormData ourself now.
• We like to reduce the complexity of the core by removing support for form-data.
• form-data have had a long time to become spec compliant but haven't done that
• using res.buffer is no good as it's a nodejs only feature, if ppl depend on this it only makes it more node-specific
  we now strive to more spec compatible ways and more cross platform solutions.

Changes

This will output a one time warning when using form-data

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• Readme recommends 2 other spec compatible alternatives already
• The onetime warning references the issue at hand to resolve this.

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• Fixes #1167

[jimmywarting]

added this also:

NodeJS plans to impl fetch into core. Guess they will be more spec compatible and not have res.buffer(). this will just be a preparations for it + it makes it more cross compatible

The alternative is that we remove it right now...

[Richienb]

Since node-fetch v3 bumps a major version, it would make sense to just remove things before a stable version ships if need be.

[jimmywarting]

I'm fine with removing form-data and buffer right now before shipping v3 if anyone else agree

[octet-stream]

I think that removing of the form-data package right away will have a huge impact and broke code for many developers. Perhaps it would be preferable to have some transition period before its support will be gone for good.

[jimmywarting]

I think that removing of the form-data package right away will have a huge impact and broke code for many developers. Perhaps it would be preferable to have some transition period before its support will be gone for good.

Where thinking quite the same thing when i made this PR.

plans for v4 could be:

• impl whatwg streams body
• remove form-data
• remove buffer()

It would give them time to prepare

[Richienb]

In which case, we could implement new features and deprecate old ones in v3 and remove them in v4.

[LinusU]

👍

[jimmywarting]

@gr2m can you review this also?

[kandaris]

So what would an alternative look like for the code below since form-data has been Deprecated?

Considering using busboy, any recommendations?

[jimmywarting]

@kandaris this only shows how you are handling the response, now how you use the form-data package.
also busboy is for decoding bodies only. not constructing them...
(fyi fetch can both encode and decoding bodies)

node-fetch have opted to use formdata-polyfill to deserializer bodies to a formdata using request.formData() or response.formData()

dos i would recommend using that one as well to avoid any other similar pacakges npm i formdata-polyfill fetch-blob

import { fileFromSync } from 'fetch-blob/from.js'
import { FormData } from 'formdata-polyfill/esm.min.js'

const fd = new FormData()
const file = fileFromSync('./package.json')

fd.append('upload', file)

fetch(url, {method: 'post', body: fd})

There are a way to get it without installing it if you do:

const FormData = (await new Response(new URLSearchParams).formData()).constructor

this way you will always depend on same version as we use.