JSON-LD Context Merging?

[lautarodragan]

We're currently merging three different JSON-LD contexts in configureCreateVerifiableClaim: the default one, the one associated with the claim type, and the user-provided one.

poet-js/src/VerifiableClaim.ts

Lines 40 to 54 in f50a701

	export const configureCreateVerifiableClaim = ({
	issuer,
	type = ClaimType.Work,
	context = {},
	}: CreateVerifiableClaimConfig) => async (claim: Claim): Promise<VerifiableClaim> => {
	const verifiableClaim = {
	'@context': { ...DefaultClaimContext, ...claimTypeDefaults[type], ...context },
	type,
	issuer,
	issuanceDate: new Date().toISOString(),
	claim,
	}
	const id = await generateClaimId(verifiableClaim)
	return { ...verifiableClaim, id }
	}

These are the contexts used to sign and serialize the whole VerifiableClaim structure, of which what we call a claim is a child object.

poet-js/src/Interfaces.ts

Lines 55 to 66 in f50a701

	export const DefaultClaimContext: ClaimContext = {
	cred: 'https://w3id.org/credentials#',
	dc: 'http://purl.org/dc/terms/',
	schema: 'http://schema.org/',
	sec: 'https://w3id.org/security#',
	id: 'sec:digestValue',
	issuer: 'cred:issuer',
	issuanceDate: 'cred:issued',
	type: 'schema:additionalType',
	claim: 'schema:Thing', // The most generic definition in schema.org,
	}

The issue is that we're listing domain-specific fields that belong inside the claim immediately inside the verifiable claim:

poet-js/src/Interfaces.ts

Lines 68 to 85 in f50a701

	export const DefaultWorkClaimContext: ClaimContext = {
	archiveUrl: 'schema:url',
	author: 'schema:author',
	canonicalUrl: 'schema:url',
	claim: 'schema:CreativeWork',
	contributors: {
	'@id': 'schema:ItemList',
	'@container': '@list',
	'@type': 'schema:contributor',
	},
	copyrightHolder: 'schema:copyrightHolder',
	dateCreated: 'schema:dateCreated',
	datePublished: 'schema:datePublished',
	license: 'schema:license',
	name: 'schema:name',
	tags: 'schema:keywords',
	hash: 'sec:digestValue',
	}

This leads to the following: taking a look at this claim, for example:

{
  "@context": {
    "cred": "https:\/\/w3id.org\/credentials#",
    "dc": "http:\/\/purl.org\/dc\/terms\/",
    "schema": "http:\/\/schema.org\/",
    "sec": "https:\/\/w3id.org\/security#",
    "id": "sec:digestValue",
    "issuer": "cred:issuer",
    "issuanceDate": "cred:issued",
    "type": "schema:additionalType",
    "claim": "schema:CreativeWork",
    "archiveUrl": "schema:url",
    "author": "schema:author",
    "canonicalUrl": "schema:url",
    "contributors": {
      "@id": "schema:ItemList",
      "@container": "@list",
      "@type": "schema:contributor"
    },
    "copyrightHolder": "schema:copyrightHolder",
    "dateCreated": "schema:dateCreated",
    "datePublished": "schema:datePublished",
    "license": "schema:license",
    "name": "schema:name",
    "tags": "schema:keywords",
    "hash": "sec:digestValue",
    "content": "schema:text",
    "creator": "schema:creator",
    "genre": "schema:genre",
    "duration": "schema:duration"
  },
  "id": "2c38ab28213532b49eb03b971dd32039900acba918db28902e3fe40b271b94bb",
  "type": "Work",
  "issuer": "data:;base64,eyJhbGdvcml0aG0iOiJFZDI1NTE5U2lnbmF0dXJlMjAxOCIsInB1YmxpY0tleSI6IkU4YkJ3cnNtSFVRYU1QcFE4NUR0VXQ5S01FNUZuR3dONmdrU1IzOVE1TWZEIn0=",
  "issuanceDate": "2019-06-25T09:18:09.452Z",
  "claim": {
    "archiveUrl": "https:\/\/ipfs.poetnetwork.net\/ipfs\/QmanrB6yaVSD7yL6T5C921nBDRkhyfMdhufBhVZwMzNUf4",
    "hash": "QmanrB6yaVSD7yL6T5C921nBDRkhyfMdhufBhVZwMzNUf4",
    "name": "Astronomy Domine",
    "datePublished": "2019-06-25T09:14:35.091Z",
    "dateCreated": "2019-06-25T09:14:35.091Z",
    "author": "Pink Floyd",
    "tags": "",
    "creator": "Syd Barrett",
    "genre": "Space Rock",
    "duration": "4:12"
  },
  "sec:proof": {
    "@graph": {
      "@type": "sec:Ed25519Signature2018",
      "dc:created": {
        "@type": "http:\/\/www.w3.org\/2001\/XMLSchema#dateTime",
        "@value": "2019-06-25T09:18:09Z"
      },
      "dc:creator": {
        "@id": "data:;base64,eyJhbGdvcml0aG0iOiJFZDI1NTE5U2lnbmF0dXJlMjAxOCIsInB1YmxpY0tleSI6IkU4YkJ3cnNtSFVRYU1QcFE4NUR0VXQ5S01FNUZuR3dONmdrU1IzOVE1TWZEIn0="
      },
      "sec:jws": "eyJhbGciOiJFZERTQSIsImI2NCI6ZmFsc2UsImNyaXQiOlsiYjY0Il19..dyQns2QnHuD7PUX77Yl3OhHYcalLxUyMsd0QyYML4wCY7xDg4sLGzzYICy1gcK0EtJGM8xQV3mJzHmeTH4s4Ag",
      "sec:nonce": "cjxblkgmu00000htie07oik49"
    }
  }
}

The archiveUrl is an immediate child of the root VerifiableClaim in the @context yet it's inside claim, which is defined as a schema:CreativeWork in the context.

This works right now. My guess is jsonld accepts fields defined in the matching element or anywhere in the context.

Q: Is this well-defined or accidental behaviour?

Either way, we'll probably want to vamp up the logic so the VerifiableClaim is a constant structure for all Po.et and the inner Claim is free form.