CODEWITHSUNDEEP
javasparqlapache-jena
SamuelTJackson
SamuelTJackson

Reputation: 1537

Sparql request for relationships

Hey I made the protege tutorial for pizzas. I got an owl file. I saved the file as RDF/XML format. Now I try to get some information about the data in the file. Things like:

"Select * where {
?s rdfs:subClassOf owl:Thing
}

work. Now I want to get all subjects and objects who are related with "hasTopping". 

OntModel m = ModelFactory.createOntologyModel(OWL_MEM);

    InputStream in = FileManager.get().open("pizza1.owl");
    m.read(in, "RDF/XML");
    String queryString =
                    "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> " +
                    "PREFIX : <http://www.pizza.com/ontologies/pizza.owl> " +
                    "PREFIX owl: <http://www.w3.org/2002/07/owl#>" +
                    "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>" +
                    "PREFIX xml: <http://www.w3.org/XML/1998/namespace>" +
                    "SELECT * WHERE" +
                    "{" +
                    "?s :hasTopping ?o" +
                    "}";
    Query query = QueryFactory.create(queryString);
    QueryExecution qexec = QueryExecutionFactory.create(query,m);
    try {
        ResultSet results = qexec.execSelect();
        while( results.hasNext()) {
            QuerySolution soln = results.nextSolution();
            RDFNode name = soln.get("s");
            RDFNode name1 = soln.get("o");


            //RDFNode name2 = soln.get("s");
            System.out.println("Subject:" + name);
            System.out.println("Object:" + name1);

            //System.out.println(name2);
        }
    } finally {
        qexec.close();
    }

But the result is always empty. Hope someone can help me.

Kindly Regards!

Upvotes: 0

Views: 41

Answers (1)

UninformedUser
UninformedUser

Reputation: 8465

The prefix declaration of : is missing a separator like # or / - depends on how it's defined in the ontology.

Without it, using :hasTopping results in the URI http://www.pizza.com/ontologies/pizza.owlhasTopping

Upvotes: 1

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