Add @container: @id

[lanthaler]

This is a proposal @niklasl made in response to the proposal to support "@container": "@language" (#133):

@container is already a mechanism for letting the two currently defined container keywords, @set and @list, interpret a given array in their own specific way. We can extend the behaviour of @container to let all of @language, @id, @type and regular terms treat an object as a map, in their own, specific ways.

To keep the discussion focused, let's concentrate on "@container": "@id" in this issue (and call it a subject map) and create separate ones for @type and regular terms if required.

Here's an example of using @container with @id (one without aliasing @graph as Niklas did):

{
  "@context": {
    "ex": "http://example.com/",
    "name": "http://xmlns.com/foaf/0.1/name",
    "homepage": { "@id": "http://xmlns.com/foaf/0.1/homepage", "@type": "@id" },
    "knows": { "@id": "http://xmlns.com/foaf/0.1/knows", "@container": "@id" }
  },
  "@id": "ex:Markus",
  "name": "Markus",
  "homepage": "http://www.markus-lanthaler.com/",
  "knows": {
    "ex:Niklas": {
     ****** what would happen if a different @id would be defined here? *****
      "name": "Niklas",
      "homepage": "http://neverspace.net/"
    }
  }
}

This would be expanded to:

[
  {
    "@id": "http://example.com/Markus",
    "http://xmlns.com/foaf/0.1/name": [ { "@value": "Markus" } ],
    "http://xmlns.com/foaf/0.1/homepage": [ { "@id": "http://www.markus-lanthaler.com/" } ],
    "http://xmlns.com/foaf/0.1/knows": [ {
      "@id": "http://example.com/Niklas",
      "http://xmlns.com/foaf/0.1/name": [ { "@value": "Niklas" } ],
      "http://xmlns.com/foaf/0.1/homepage": [ { "@id": "http://neverspace.net/" } ]
    } ]
  }
]

A couple of questions:

• what should happen if a different IRI is assigned to an object in a subject map
• should properties of subject maps be interpreted as relative IRIs as fallback, i.e., the same way as values of @id

---

Gregg originally proposed to use something he called "folding" for this and #133:

{
  "@context": {
    "en": {"@id": null", "@language": "en", "@fold": true},
    "de": {"@id": null", "@language": "de", "@fold": true},
    "queenie": {"@id": null", "@fold": true}
  },
  "queenie": {
    "@id": "http://buckingham.uk/queenie",
    "label": {
      "en": { "@value": "The Queen" },
      "de": { "@value": "Die Königin"}
    }
  }
}

[gkellogg]

So, I think this works. I would say that @id in the object trumps the property. I think this might be simpler to work in with the current expansion algorithm too.

[gkellogg]

RESOLVED: Attempt to add other @container options, such as "@container": "@language" to support Wikidata's language-map use case.

[lanthaler]

RESOLVED: Do not support "@container": "@id" in JSON-LD 1.0.