Is it possible to get the nested json output in SPARQL? - sparql

Question

I am using MarkLogic 8.0-6.3
I came across a scenario where I need nested JSON output in SPARQL.
For example there are multiple same predicates for an IRI, in the result I want the multiple values in array not as a whole triple.
for example:
Assume triples:
#prefix p0: <http://www.mla.com/term/> .
p0:7 <http://www.w3.org/2004/02/skos/core#narrower> p0:768 ,
p0:769 ,
p0:770 ,
p0:771 .
SPARQL query:
PREFIX skos-mla: <http://www.mlacustom.com#>
PREFIX term: <http://www.mla.com/term/>
select ?iri ?o {
graph<thesaurus-term>{
bind(term:7 as ?iri)
term:7 skos:narrower ?o .
}
}
the above query will return the 4 triples as output.
What I want is it should just return me a single json structure like
{
"iri": "http://www.mla.com/term/7",
"narrowers": ["http://www.mla.com/term/768", "http://www.mla.com/term/769", "http://www.mla.com/term/770", "http://www.mla.com/term/771"]
}
Above JSON is just to explain the problem.
In actual I would need a more complex json structure like instead of string array I need an array of json objects.
I know that I can read the response and recreate the whole json in any format but it has performance impacts.

Answer 1

In recent versions of MarkLogic 9, the Optic API can support this requirement:
Use the op.fromSPARQL() accessor to project columns of values from the triples.
Chain a select() call using op.jsonObject() to collect the values as properties of objects.
Chain a groupBy() call using op.arrayAggregate() to aggregate the objects in an array.
Chain a result() call to get the output.
For more information, see:
http://docs.marklogic.com/op.jsonObject
and:
http://docs.marklogic.com/op.arrayAggregate
Hoping that helps,