Re: Differences in IRI compaction of "@id" and "@type"

Hi Gregg,

thanks for providing the reference to the JSON-LD 1.1 specification to
explain the IRI compaction behaviour!

- Jindrich

On Thu, 26 Aug 2021 at 22:15, Gregg Kellogg <gregg@greggkellogg.net> wrote:

> On Aug 26, 2021, at 7:20 AM, Jindřich Mynarz <mynarzjindrich@gmail.com>
> wrote:
>
> Hi,
>
> I'm wondering about the differences in JSON-LD API's IRI compaction (
> https://www.w3.org/TR/json-ld-api/#iri-compaction) of "@id" and "@type".
> When I compact the following data:
>
> {
>   "@type": "http://example.com/A",
>   "http://example.com/property": {"@id": "http://example.com/B"}
> }
>
> With the following JSON-LD context:
>
> {
>   "@vocab": "http://example.com/",
>   "ex": "http://example.com/",
>   "AliasedA": "A",
>   "AliasedB": "B",
>   "property": {"@type": "@id"}
> }
>
> The JSON-LD Playground (https://json-ld.org/playground, running jsonld.js
> compliant with JSON-LD 1.1) returns the following compacted data:
>
> {
>   "@context": {
>     "@vocab": "http://example.com/",
>     "ex": "http://example.com/",
>     "AliasedA": "A",
>     "AliasedB": "B",
>     "property": {
>       "@type": "@id"
>     }
>   },
>   "@type": "AliasedA",
>   "property": "ex:B"
> }
>
> While the value of "@type" is compacted to its alias term, the value of
> "@id" is only compacted using a prefix definition, not its alias term.
>
>
> The rules for interpreting strings as IRIs are described in 4.2.3 Type
> Coercion [1]. Terms used as properties can be defined using with either
> “@type”: “@id” or “@type”: “@vocab” indicate that they should be
> interpreted as IRI references, and are either relative to the document base
> or vocabulary base. By default, values of “@type” are interpreted as IRI
> references relative to the vocabulary base, and “@id” relative to the
> document base.
>
> It is important to note that terms are only used in expansion for
> vocabulary-relative positions, such as for keys and values of map entries.
> Values of @id are considered to be document-relative, and do not use term
> definitions for expansion.
>
>
> Because @id is document relative, without specifying a document base, it
> can’t be turned into a relative IRI, but it can potentially be turned into
> a compact IRI, given a suitable term definition to use as the prefix. The
> value of @type, and other properties (which use “@type”: “@vocab”) can
> potentially be compacted as IRI references/relative IRIs.
>
> When compacting, the most suitable term definition matching the value of a
> given node key is used for creating the compacted result, through a fairly
> involved process.
>
> Link into JSON-LD Playground: https://tinyurl.com/yfrzckbr
>
> I'm guessing values of "@type" are treated differently by IRI compaction,
> but I cannot find support for that in the JSON-LD API specification. Can
> you help?
>
>
> Gregg Kellogg
> gregg@greggkellogg.net
>
> [1] https://www.w3.org/TR/json-ld11/#type-coercion
>
>
> Best regards,
>
> Jindrich
>
> --
> Jindrich Mynarz
> https://mynarz.net/#jindrich
>
>
>