Per-asset configuration: query parameters or something else?

[rhendric]

I'm trying to write a Parcel v2 transformer that edits font files down to a given subset of glyphs.

Each font file should have its glyph subset defined independently, and I also want to be able to embed the resulting font directly into the CSS referencing it with a data: URL. My first thought was to use query parameters in the URL that Parcel resolves: something like url('path/to/source/font.woff2?subset=<glyphs to include>'), with an optional data-url: at the front if I want to embed the resulting font. However, starting down this path, my Transformer gets called but the query property on the asset is undefined.

Is there another way to get the query parameters of an asset from a transformer? Or, perhaps more importantly, does Parcel want me to provide per-asset configuration like this in some other way, a way which hopefully is also compatible with using a named pipeline like data-url:?

[mischnic]

This already exists:

parcel/packages/transformers/image/src/ImageTransformer.js

Lines 19 to 24 in 069a2b1

	let width = asset.query.width ? parseInt(asset.query.width, 10) : null;
	let height = asset.query.height ? parseInt(asset.query.height, 10) : null;
	let quality = asset.query.quality
	? parseInt(asset.query.quality, 10)
	: undefined;
	let format = asset.query.as ? asset.query.as.toLowerCase().trim() : null;

import image from 'url:./image.jpg?height=200';
import image from 'url:./image.webp?height=200&width=300';
import image from 'url:./image.png?width=300';

#4881

[rhendric]

Yeah, that was my initial inspiration; I just didn't know if it was the latest encouraged pattern, since I could only find it used in that one transformer.

Turns out the reason my attempts weren't working is down to a bug that will hopefully be fixed when #5228 is merged.

[mischnic]

if it was the latest encouraged pattern, since I could only find it used in that one transformer.

It's just that it wasn't needed for any other transformer previously and it was then implemented together with the image transformer.