org.apache.jena.query.ParameterizedSparqlString Java Examples

protected Query convertToSelect(ParameterizedSparqlString pss, Set<String> varNames) {
	Query queryCpy = pss.asQuery();
	queryCpy.getQueryPattern();

	StringBuilder queryStr = new StringBuilder("SELECT DISTINCT ");
	for(String varName : varNames) {
		queryStr.append("?").append(varName).append(" ");
	}
	queryStr.append(queryCpy.getQueryPattern());
	ParameterizedSparqlString pssSelect = new ParameterizedSparqlString();
	pssSelect.setCommandText(queryStr.toString());
	pssSelect.setNsPrefixes(pss.getNsPrefixMap());
	pssSelect.append(" LIMIT ");
	pssSelect.append(this.limit);
	System.out.println(pssSelect);
	return pssSelect.asQuery();
}
 

private String injectTarget(String sparqlQuery, ShapeTarget target) {
    String changedQuery = sparqlQuery;

    if (target.getTargetType().equals(ShapeTargetType.NodeTarget)) {
        changedQuery = sparqlQuery
                .replaceFirst("[\\$\\?]this", thisVar )
                .replaceAll("(?i)BOUND\\s*\\(\\s*[\\$\\?]this\\s*\\)", "BOUND\\("+ thisVar+"\\)")
                .replaceAll("(?i)GROUP\\s+BY\\s+[\\$\\?]this", "GROUP BY "+ thisVar);

        QuerySolutionMap qsm = new QuerySolutionMap();
        qsm.add(CommonNames.This, target.getNode());
        ParameterizedSparqlString pq = new ParameterizedSparqlString(changedQuery, qsm);
        changedQuery = pq.toString();

        changedQuery = changedQuery
                .replaceFirst(thisVar, "\\$this")
                .replaceAll("(?i)BOUND\\("+ thisVar+"\\)", "BOUND\\(\\?this\\)")
                .replaceAll("(?i)GROUP BY "+ thisVar, "GROUP BY \\$this");
    }

    return injectSparqlSnippet(changedQuery, target.getPattern());
}
 

/**
 * The Wikipedia Id or -1 if the Id couldn't be retrieved.
 * 
 * FIXME The method throws an exception for "http://DBpedia.org/resource/Origin_of_the_name_"Empire_State"". this
 * might be happen because of the quotes inside the URI.
 * 
 * @param dbpediaUri
 * @return
 */
@Deprecated
public static int getIdFromDBpedia(String dbpediaUri) {
    int id = -1;
    ParameterizedSparqlString query = new ParameterizedSparqlString(
            "SELECT ?id WHERE { ?dbpedia dbo:wikiPageID ?id .}", prefixes);
    query.setIri("dbpedia", dbpediaUri);
    QueryExecution qexec = null;
    try {
        qexec = QueryExecutionFactory.create(query.asQuery(),
                model);
    } catch (QueryParseException e) {
        LOGGER.error("Got a bad dbpediaUri \"" + dbpediaUri
                + "\" which couldn't be parse inside of a SPARQL query. Returning -1.", e);
        return id;
    }
    ResultSet result = qexec.execSelect();
    if (result.hasNext()) {
        id = result.next().get("id").asLiteral().getInt();
        return id;
    }
    qexec = QueryExecutionFactory.sparqlService(
            "http://dbpedia.org/sparql", query.asQuery());
    result = qexec.execSelect();
    if (result.hasNext()) {
        id = result.next().get("id").asLiteral().getInt();
        model.add(new StatementImpl(model.createResource(dbpediaUri), model
                .createProperty("http://dbpedia.org/ontology/wikiPageID"),
                model.createTypedLiteral(id)));
        return id;
    }

    model.add(new StatementImpl(model.createResource(dbpediaUri), model
            .createProperty("http://dbpedia.org/ontology/wikiPageID"),
            model.createTypedLiteral(id)));
    return id;
}
 

/**
 * Tests the convert to select method
 */
@Test
public void testConverting() {
	ParameterizedSparqlString pss = new ParameterizedSparqlString();
	pss.setCommandText(query);
	
	assertEquals(QueryFactory.create(expectedQuery), handler.convertToSelect(pss, varNames));
}
 

static String getBindedSparql(String sparql, RDFNode node) {
    ParameterizedSparqlString parameterizedSparqlString = new ParameterizedSparqlString("ASK{" +sparql+ "}");
    parameterizedSparqlString.setParam("target", node);
    String queryPattern = parameterizedSparqlString
            .toString()
            .trim()
            .replace("ASK{", "");
    // remove last '}'
    return queryPattern.substring(0, queryPattern.length()-1);
}
 

protected Set<String> getInstances(String queryStr) {
	Set<String> instances = new HashSet<String>();

	//check if query is already an instance
	try{
		QueryFactory.create(queryStr);
		//query is instance
		LOGGER.debug("[QueryHandler: {{}}] Query is already an instance: {{}}", this.getClass().getName(), queryStr);
		instances.add(queryStr);
		return instances;
	}catch(Exception e) {
		//query is pattern, nothing to do
	}
	
	//get vars from queryStr
	Set<String> varNames = new HashSet<String>();
	String command = replaceVars(queryStr, varNames);
	
	//generate parameterized sparql query
	ParameterizedSparqlString pss = new ParameterizedSparqlString();
	pss.setCommandText(command);
	ResultSet exchange = getInstanceVars(pss, varNames);		
	System.out.println("instaces retrieved");
	// exchange vars in PSS
	if(!exchange.hasNext()) {
		//no solution
		System.out.println("No solution");
		LOGGER.warn("[QueryHandler: {{}}] Query has no solution, will use variables instead of var instances: {{}}", this.getClass().getName(), queryStr);
		instances.add(command);
	}
	while(exchange.hasNext()) {
		QuerySolution solution = exchange.next();
		for(String var : exchange.getResultVars()) {
			//exchange variable with 
			pss.clearParam(var);
			pss.setParam(var, solution.get(var));
		}
		instances.add(pss.toString());
	}
	System.out.println("Found instances "+instances);

	return instances;
}
 

protected ResultSet getInstanceVars(ParameterizedSparqlString pss, Set<String> varNames) {
	QueryExecution exec = QueryExecutionFactory.createServiceRequest(service, convertToSelect(pss,varNames));
	//return result set
	return exec.execSelect();
}
 

/**
 *
 * @param subject
 * @param predicate
 * @param object
 * @param offset
 * @param limit
 * @return
 */
@Override
protected ILinkedDataFragment createFragment(
           final ITriplePatternElement<RDFNode,String,String> subject,
           final ITriplePatternElement<RDFNode,String,String> predicate,
           final ITriplePatternElement<RDFNode,String,String> object,
           final long offset,
           final long limit )
{
    // FIXME: The following algorithm is incorrect for cases in which
    //        the requested triple pattern contains a specific variable
    //        multiple times;
    //        e.g., (?x foaf:knows ?x ) or (_:bn foaf:knows _:bn)
    // see https://github.com/LinkedDataFragments/Server.Java/issues/24

    QuerySolutionMap map = new QuerySolutionMap();
    if ( ! subject.isVariable() ) {
        map.add("s", subject.asConstantTerm());
    }
    if ( ! predicate.isVariable() ) {
        map.add("p", predicate.asConstantTerm());
    }
    if ( ! object.isVariable() ) {
        map.add("o", object.asConstantTerm());
    }

    query.setOffset(offset);
    query.setLimit(limit);

    Model triples = ModelFactory.createDefaultModel();

    // Build the SPARQL-endpoint
    URIBuilder uriBuilder = new URIBuilder(endpointURI);
    addCredentials(uriBuilder);

    final String endpoint;
    try {
        endpoint = uriBuilder.build().toString();
    } catch (URISyntaxException e) {
        throw new RuntimeException(e);
    }

    ParameterizedSparqlString queryWithParams = new ParameterizedSparqlString(query.serialize(), map);

    try (QueryExecution qexec = QueryExecutionFactory.sparqlService(endpoint, queryWithParams.asQuery())) {
        qexec.execConstruct(triples);
    }

    if (triples.isEmpty()) {
        return createEmptyTriplePatternFragment();
    }

    // Try to get an estimate
    long size = triples.size();
    long estimate = -1;

    ParameterizedSparqlString countQueryWithParams = new ParameterizedSparqlString(countQuery.serialize(), map);

    try (QueryExecution qexec = QueryExecutionFactory.createServiceRequest(endpoint, countQueryWithParams.asQuery())) {
        ResultSet results = qexec.execSelect();
        if (results.hasNext()) {
            QuerySolution soln = results.nextSolution() ;
            Literal literal = soln.getLiteral("count");
            estimate = literal.getLong();
        }
    }

    /*GraphStatisticsHandler stats = model.getGraph().getStatisticsHandler();
    if (stats != null) {
        Node s = (subject != null) ? subject.asNode() : null;
        Node p = (predicate != null) ? predicate.asNode() : null;
        Node o = (object != null) ? object.asNode() : null;
        estimate = stats.getStatistic(s, p, o);
    }*/

    // No estimate or incorrect
    if (estimate < offset + size) {
        estimate = (size == limit) ? offset + size + 1 : offset + size;
    }

    // create the fragment
    final boolean isLastPage = ( estimate < offset + limit );
    return createTriplePatternFragment( triples, estimate, isLastPage );
}