W3C home > Mailing lists > Public > public-hydra@w3.org > July 2014

RE: Introduction and a question about JSON-LD

From: Markus Lanthaler <markus.lanthaler@gmx.net>
Date: Sat, 26 Jul 2014 20:59:44 -0400
To: <public-hydra@w3.org>
Message-ID: <033301cfa936$0e366e10$2aa34a30$@gmx.net>
On 26 Jul 2014 at 02:06, john.walker wrote: 
>> On July 26, 2014 at 6:37 AM Markus Lanthaler wrote:
>> On 25 Jul 2014 at 13:37, john.walker wrote:
>>> As you can see I used the Schema.org context off GitHub served
>>> via RawGit so that it plays nice in the JSON-LD playground.
>>> Ideally you would just need to use "http://schema.org/", but that
>>> doesn't work in the playground (guess it sends wrong Accept
>>> header when fetching the context).
>> 
>> Which browser do you use? It works for me in the latest versions of
>> Chrome, IE, and Firefox. 
> 
> I'm using Chrome  Version 36.0.1985.125 m
> 
> It's not that it throws an error, more that the resulting N-Quads are
> not what I expect.

Oh OK. That's a different story then :-)


> EXAMPLE 1:
> 
> {
>   "@context": [
>     "http://schema.org/"
>   ],
>   "@id": "dimitri",
>   "homeLocation": "Tilburg"
> }
> 
> Yields:
> 
> <http://json-ld.org/playground/dimitri> <http://schema.org/homeLocation>
> "Tilburg" .

Yeah. This is correct and is what (I think) most people would expect. Please note that schema.org allows string literals to be used almost anywhere.


> EXAMPLE 2:
> 
> {
>   "@context": [
>     "https://rawgit.com/json-ld/json-ld.org/master/contexts/schema.org.jsonld"
>   ],
>   "@id": "dimitri",
>   "homeLocation": "Tilburg"
> }
> 
> Yields:
> 
> <http://json-ld.org/playground/dimitri> <http://schema.org/homeLocation>
> <http://json-ld.org/playground/Tilburg> .
> 
> Note that in example 1 the object is a literal value, but in example 2 is a URI.
> My mistake was assuming these two context documents had the same content.

The schema.org context on json-ld.org was more or less a hack to have something till schema.org publishes their context. It hasn't been updated for quite a while. I will propose to delete it to avoid further confusion.


> However it seems that schema:hasLocation is not defined as having @id as the
> @type in the context served from http://schema.org/
> 
> So in conclusion the playground is working fine :) , but the 'official'
> Schema.org context could do with a few additions :(

Type-coercing properties to @id should only be done if string literals don't make much sense. Thus, the heuristic that is used when creating the Schema.org context is to look for schema:rangeIncludes schema:URL. If URL isn't in the range, the property won't be coerced to @id.

As you know, you can always easily overlay those type-coercions yourself:

  {
    "@context": [
      "http://schema.org/",
      { "homeLocation": { "@type": "@id" } }
    ],
    "@id": "dimitri",
    "homeLocation": "Tilburg"
  }
 


--
Markus Lanthaler
@markuslanthaler
Received on Sunday, 27 July 2014 01:00:16 UTC

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