Helpers to change the Description Resource

[elf-pavlik]

• https://solidproject.org/TR/protocol#auxiliary-resources-description-resource
• https://communitysolidserver.github.io/CommunitySolidServer/latest/usage/metadata/

I don't have a clear idea of the expected interface. Hopefully, I will be able to come up with some options.

Here are a few things to keep in mind:

• The subject resource has to be created first
• Since the response to PUT doesn't include the Link header, we need HEAD to get the describedby relation.
• LdoObject for the description will use the subject resource as the subject but needs to PATCH the description resource, not the subject resource

An example of how I'm using it currently, blob is a File:

const { ok } = await session.rawFetch(fileId, {
  method: 'PUT',
  headers: { 'Content-Type': blob.type },
  body: blob
});

const descriptionIri = await session.discoverDescription(fileId)

const newFile = solidLdoDataset.usingType(FileShapeType)
  .fromSubject(fileId);

const resource = solidLdoDataset.getResource(descriptionIri);
const cFile = changeData(newFile, resource);
cFile.fileName = blob.name
cFile.format = blob.type

const fileResult = await commitData(cFile)

Given shape

PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX solidshapes: <http://localhost:3000/shapetrees/shapes/>
PREFIX nfo: <http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#>
PREFIX ma: <http://www.w3.org/ns/ma-ont#>

solidshapes:File {
  nfo:fileName xsd:string ;
  ma:format xsd:string
}

I always use opaque IRIs generated with randomUUID. I'm saving the original file name and using it when offering a download https://developer.mozilla.org/en-US/docs/Web/API/HTMLAnchorElement/download