Re: json-ld and sparql

On 3/15/16 3:01 PM, John Walker wrote:
> Hi Kingsley,
>
> On 15 Mar 2016, at 17:21, "Kingsley Idehen" <kidehen@openlinksw.com
> <mailto:kidehen@openlinksw.com>> wrote:
>
>> On 3/15/16 11:53 AM, John Walker wrote:
>>> Hi Jean-Claude,
>>>
>>> Try using the CONSTRUCT form of SPARQL and use Accept header to
>>> request results in JSON-LD.
>>>
>>> prefix schema: <http://schema.org/>
>>> construct where {
>>> ?p a schema:Place .
>>> ?p rdfs:label ?name .
>>> ?p geo:lat ?lat .
>>> ?p geo:long ?lon .
>>> }
>>> LIMIT 5
>>>
>>> Regards,
>>> John
>>
>> Hi John,
>>
>> As per my earlier comment, the following will do:
>>
>> prefix schema: <http://schema.org/>
>> *describe ?p* where {
>> ?p a schema:Place .
>> ?p rdfs:label ?name .
>> ?p geo:lat ?lat .
>> ?p geo:long ?lon .
>> }
>> LIMIT 5
>
> Sure, but you may also get a bunch of extra data you don't want/need.

Yes, and in that case you can ultimately resort to a CONSTRUCT query. I
offered DESCRIBE because it let's the user get a feel for how entity
descriptions are represented before diving deeper into a more specific
CONSTRUCT query

>
> Main point is to use a query that returns a graph response rather than
> a table.

Yes.


Kingsley
>>
>> SPARQL Query Editor Source Code Link:
>>
>>
>> curl -i
>> "http://dbpedia.org/sparql?default-graph-uri=http%3A%2F%2Fdbpedia.org&qtxt=prefix+schema%3A+%3Chttp%3A%2F%2Fschema.org%2F%3E%0D%0Adescribe++%3Fp++where+%7B%0D%0A%3Fp+a+schema%3APlace+.%0D%0A%3Fp+rdfs%3Alabel+%3Fname+.%0D%0A%3Fp+geo%3Alat+%3Flat+.%0D%0A%3Fp+geo%3Along+%3Flon+.%0D%0A%7D+LIMIT+5&format=application%2Fld%2Bjson&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on"
>>
>>
>> Kingsley
>>>
>>> On 15 Mar 2016, at 14:35, "Jean-Claude Moissinac"
>>> <jean-claude.moissinac@telecom-paristech.fr> wrote:
>>>
>>>> I'm trying to find best practices in the use of a json output from
>>>> a sparql endpoint
>>>> For exemple the request on dbpedia :
>>>> prefix schema: <http://schema.org/>
>>>> select distinct ?p ?name ?lat ?lon where {
>>>> ?p a schema:Place .
>>>> ?p rdfs:label ?name .
>>>> ?p geo:lat ?lat .
>>>> ?p geo:long ?lon .
>>>> } LIMIT 5
>>>> give me as json output
>>>> { "head": { "link": [], "vars": ["p", "name", "lat", "lon"] },
>>>>   "results": { "distinct": false, "ordered": true, "bindings": [
>>>>     { "p": { "type": "uri", "value": "http://dbpedia.org/resource/Cameron_Parish,_Louisiana" }	, "name": { "type": "literal", "xml:lang": "en", "value": "Cameron Parish, Louisiana" }	, "lat": { "type": "typed-literal", "datatype": "http://www.w3.org/2001/XMLSchema#float", "value": "29.85" }	, "lon": { "type": "typed-literal", "datatype": "http://www.w3.org/2001/XMLSchema#float", "value": "-93.2" }},
>>>>     { "p": { "type": "uri", "value": "http://dbpedia.org/resource/Cameron_Parish,_Louisiana" }	, "name": { "type": "literal", "xml:lang": "ar", "value": "\u0645\u0642\u0627\u0637\u0639\u0629 \u0643\u0627\u0645\u064A\u0631\u0648\u0646 (\u0644\u0648\u064A\u0632\u064A\u0627\u0646\u0627)" }	, "lat": { "type": "typed-literal", "datatype": "http://www.w3.org/2001/XMLSchema#float", "value": "29.85" }	, "lon": { "type": "typed-literal", "datatype": "http://www.w3.org/2001/XMLSchema#float", "value": "-93.2" }},
>>>> ... < cut for clarity >
>>>>  }} ] } }
>>>> We loose the fact that ?p is a Place. We can factorize the 'type'
>>>> on the table of results. And finally get a table of objects like
>>>> thos one
>>>> {
>>>>     "p ":  "http://dbpedia.org/resource/Cameron_Parish,_Louisiana",
>>>> "name": "Cameron Parish, Louisiana",
>>>> "pos": { "lat": 29.85, "long": 93.2 }
>>>> }
>>>> I suppose some results can be obtained by using a context and some
>>>> others by framing.
>>>> Can we point me on ideas for clarification?
>>>> Many thanks in advance
>>>> --
>>>> Jean-Claude Moissinac
>>>>
>>>>
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>>>>
>>>>
>>
>>
>> -- 
>> Regards,
>>
>> Kingsley Idehen	      
>> Founder & CEO 
>> OpenLink Software     
>> Company Web: http://www.openlinksw.com
>> Personal Weblog 1: http://kidehen.blogspot.com
>> Personal Weblog 2: http://www.openlinksw.com/blog/~kidehen
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-- 
Regards,

Kingsley Idehen	      
Founder & CEO 
OpenLink Software     
Company Web: http://www.openlinksw.com
Personal Weblog 1: http://kidehen.blogspot.com
Personal Weblog 2: http://www.openlinksw.com/blog/~kidehen
Twitter Profile: https://twitter.com/kidehen
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