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Re: JSON-LD and multiple values

From: John Walker <john.walker@semaku.com>
Date: Tue, 9 Jun 2015 14:52:13 +0200
Message-Id: <FBB78ED7-BC59-44E0-8D54-4BB7F53D2A05@semaku.com>
Cc: "mfhepp@gmail.com" <mfhepp@gmail.com>, Melvin Carvalho <melvincarvalho@gmail.com>, Gregg Kellogg <gregg@greggkellogg.net>, Manu Sporny <msporny@digitalbazaar.com>, "schema.org Mailing List" <public-schemaorg@w3.org>
To: Dan Brickley <danbri@google.com>
For the record I-JSON forbids duplicate names in an object:
https://tools.ietf.org/html/rfc7493#section-2.3

I had the idea that a conformant JSON-LD serialisation is, per definition, also conformant to I-JSON.

Regards,
John

On 9 Jun 2015, at 13:29, Dan Brickley <danbri@google.com> wrote:

> On 9 June 2015 at 10:35, mfhepp@gmail.com <mfhepp@gmail.com> wrote:
>> Melvin:
>> I might not have made my point clear: This is not a problem of not being able to represent an RDF structure in JSON-LD, but that
>> 
>> 1. the correct pattern in JSON-LD (list/array) is different from the pattern in Turtle, RDFa, RDF/XML etc. (repetition of the same property) and
>> 2. that naively using the pattern from the other syntaxes fails *silently* in JSON-LD (just the last value is recognized).
> 
> This is broadly analogous to the rule in RDF/XML (inherited from XML
> and HTML) that multiple attributes of the same name can't exist. In
> RDF/XML that's why we also encoded properties via sub-elements, and
> the rule was well known. In JSON, well
> https://www.tbray.org/ongoing/When/201x/2013/02/21/JSON-Lesson ...
> expresses the situation nicely.
> 
> (http://linter.structured-data.org/ doesn't seem to complain btw)
> 
> Hopefully we don't have any of these in schema.org's examples. If any
> have slipped through, please file a bug -
> http://github.com/schemaorg/schemaorg/issues ... I haven't found a
> convenient way of checking automatically yet.
> 
> Dan
> 
>> Try my two examples in the Google Structured Data Testing tool and you will see the difference.
>> 
>> Martin
>> 
>> -----------------------------------
>> martin hepp  http://www.heppnetz.de
>> mhepp@computer.org          @mfhepp
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>>> On 09 Jun 2015, at 11:23, Melvin Carvalho <melvincarvalho@gmail.com> wrote:
>>> 
>>> 
>>> 
>>> On 9 June 2015 at 10:59, mfhepp@gmail.com <mfhepp@gmail.com> wrote:
>>> Dear Gregg,
>>> dear Manu:
>>> 
>>> I think there is a need for clarifying the proper use of multiple values for the same property in JSON-LD because if I understand it properly, the behavior differs from any other RDF syntax and Microdata (see [1]), as you CANNOT simply repeat a property with different values, as in any other RDF syntax, like so
>>> 
>>> I thought all RDF can be converted to JSON LD?
>>> 
>>> JSON-LD is capable of serializing any RDF graph or dataset and most, but not all, JSON-LD documents can be directly interpreted as RDF as described in RDF 1.1 Concepts [RDF11-CONCEPTS].
>>> 
>>> http://www.w3.org/TR/json-ld/#relationship-to-rdf
>>> 
>>> 
>>> 
>>> <script type="application/ld+json">
>>> {
>>>  "@context": "http://schema.org",
>>>  "@type": "Offer",
>>>  "businessFunction" : "http://purl.org/goodrelations/v1#Repair",
>>>  "businessFunction" : "http://purl.org/goodrelations/v1#Sell"
>>> 
>>> }
>>> </script>
>>> 
>>> but instead must use a LIST of values, like so:
>>> 
>>> 
>>> <script type="application/ld+json">
>>> {
>>>  "@context": "http://schema.org",
>>>  "@type": "Offer",
>>>  "businessFunction": ["http://purl.org/goodrelations/v1#Repair", "http://purl.org/goodrelations/v1#Sell" ]
>>> 
>>> }
>>> </script>
>>> 
>>> The Google Structured Data Testing Tool shows only the value for the last use of the same property name, but in complex data structures, this will be easy to overlook.
>>> 
>>> We should highlight this prominently (and review all of our examples in schema.org), because otherwise people will have a hard time understanding why only part of their data is understood.
>>> 
>>> In particular, product feature markup with many usages of "additionalProperty" will be prone to this.
>>> 
>>> Best
>>> 
>>> Martin
>>> 
>>> [1] http://webmasters.stackexchange.com/questions/81080/using-productontology-org-to-add-multiple-types/81081#81081
>>> 
>>> 
>>> -----------------------------------
>>> martin hepp  http://www.heppnetz.de
>>> mhepp@computer.org          @mfhepp
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>> 
> 
Received on Tuesday, 9 June 2015 12:52:52 UTC

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