CODEWITHSUNDEEP
sparqlrdfvirtuosordfstoresparqlwrapper
S M Shamimul Hasan
S M Shamimul Hasan

Reputation: 6694

SPARQL: How to combine two subjects to use in CONSTRUCT?

I am writing an SPARQL query where I am creating an RDF graph. I am using SPARQL CONSTRUCT. As a requirement of my work, I have to concatenate two subject values and used it with CONSTRUCT statement. I have tried to do following (my RDF graph is in Virtuoso):

prefix map: <#> 
prefix db: <> 
prefix vocab: <vocab/> 
prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
prefix xsd: <http://www.w3.org/2001/XMLSchema#> 
prefix d2rq: <http://www.wiwiss.fu-berlin.de/suhl/bizer/D2RQ/0.1#> 
prefix jdbc: <http://d2rq.org/terms/jdbc/>
prefix fn: <http://www.w3.org/2005/xpath-functions#> 

CONSTRUCT {
?p1 a d2rq:ClassMap
}

FROM <http://www.ndssl.bi.vt.edu/fuse>
WHERE 
{ 
<http://www.ndssl.bi.vt.edu/fuse#DataSource> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
<http://www.ndssl.bi.vt.edu/fuse#OracleDataSource>  <http://www.w3.org/2000/01/rdf-schema#subClassOf> <http://www.ndssl.bi.vt.edu/fuse#DataSource>.
?DB <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>   <http://www.ndssl.bi.vt.edu/fuse#OracleDataSource>.
<http://www.ndssl.bi.vt.edu/fuse#HouseholdsWithinAdminRegion> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://www.w3.org/2002/07/owl#Class>.
?Table <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>   <http://www.ndssl.bi.vt.edu/fuse#HouseholdsWithinAdminRegion>.
BIND(CONCAT(?DB, ?Table) AS ?p1)
}

However, I am getting following Error:

Virtuoso RDF01 Error Bad variable value in CONSTRUCT: "http://www.ndssl.bi.vt.edu/fuse#PROTOPOPhttp://www.ndssl.bi.vt.edu/fuse#MIAMI_HOUSEHOLD_2009_1" (tag 246 box flags 0) is not a valid subject, only object of a triple can be a literal

Please let me know how to solve it.

Upvotes: 1

Views: 1481

Answers (1)

Artemis
Artemis

Reputation: 3301

The error is basically saying that you are concatenating two URIs:

http://www.ndssl.bi.vt.edu/fuse#PROTOPOP
http://www.ndssl.bi.vt.edu/fuse#MIAMI_HOUSEHOLD_2009_1

into a literal. I don't know what you are exactly trying to do, but do you really want to concat the WHOLE URI or only the last part after the #? If you want to concat after the # you need to omit the namespace.

bind (concat(strafter(str(?s),str(fuse:)), strafter(str(?o),str(fuse:))) as ?p)

Even at this stage the result of the bind is a literal that you need to convert into a URI.

bind (uri(concat(strafter(str(?s),str(fuse:)), strafter(str(?o),str(fuse:)))) as ?p)

Generally I would simplify your query massively:

prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
prefix fuse: <http://www.ndssl.bi.vt.edu/fuse#>
prefix owl:<http://www.w3.org/2002/07/owl#>

CONSTRUCT {
    ?p1 a d2rq:ClassMap
}

FROM <http://www.ndssl.bi.vt.edu/fuse>
WHERE 
{ 
    fuse:DataSource a owl:Class.
    fuse:OracleDataSource  rdfs:subClassOf fuse:DataSource.
    ?DB a   fuse:DataSource.
    fuse:HouseholdsWithinAdminRegion a owl:Class.
    ?Table a  fuse:HouseholdsWithinAdminRegion.

    bind (uri(concat(strafter(str(?DB),str(fuse:)), 
        strafter(str(?Table),str(fuse:)))) as ?p)
}

Upvotes: 3

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