Java Code Examples for org.openrdf.query.GraphQuery#evaluate()

/**
 * Execute a CONSTRUCT/DESCRIBE SPARQL query against the graphs
 * 
 * @param qs
 *            CONSTRUCT or DESCRIBE SPARQL query
 * @param format
 *            the serialization format for the returned graph
 * @return serialized graph of results
 */
public String runSPARQL(String qs, RDFFormat format) {
	try {
		RepositoryConnection con = currentRepository.getConnection();
		try {
			GraphQuery query = con.prepareGraphQuery(
					org.openrdf.query.QueryLanguage.SPARQL, qs);
			StringWriter stringout = new StringWriter();
			RDFWriter w = Rio.createWriter(format, stringout);
			query.evaluate(w);
			return stringout.toString();
		} finally {
			con.close();
		}
	} catch (Exception e) {
		e.printStackTrace();
	}
	return null;
}
 

@Override
public ClosableIterable<Statement> queryConstruct(String queryString, String queryLanguage)
        throws QueryLanguageNotSupportedException, ModelRuntimeException {
	this.assertModel();
	// resolve the query language String to a QueryLanguage
	QueryLanguage language = ConversionUtil.toOpenRDFQueryLanguage(queryLanguage);
	
	try {
		// determine query result
		GraphQuery query = this.connection.prepareGraphQuery(language, queryString);
		GraphQueryResult queryResult = query.evaluate();
		
		// wrap it in a GraphIterable
		return new GraphIterable(queryResult, null);
	} catch(OpenRDFException e) {
		throw new ModelRuntimeException(e);
	}
}
 

/**
 * Execute a "construct" query.
 * 
 * @param repo
 * @param query
 * @param ql
 * @throws Exception
 */
public void executeConstructQuery(Repository repo, String query, 
    QueryLanguage ql) throws Exception {
    
    /*
     * With MVCC, you read from a historical state to avoid blocking and
     * being blocked by writers.  BigdataSailRepository.getQueryConnection
     * gives you a view of the repository at the last commit point.
     */
    RepositoryConnection cxn;
    if (repo instanceof BigdataSailRepository) { 
        cxn = ((BigdataSailRepository) repo).getReadOnlyConnection();
    } else {
        cxn = repo.getConnection();
    }
    
    try {

        // silly construct queries, can't guarantee distinct results
        final Set<Statement> results = new LinkedHashSet<Statement>();
        final GraphQuery graphQuery = cxn.prepareGraphQuery(ql, query);
        graphQuery.setIncludeInferred(true /* includeInferred */);
        graphQuery.evaluate(new StatementCollector(results));
        // do something with the results
        for (Statement stmt : results) {
            log.info(stmt);
        }

    } finally {
        // close the repository connection
        cxn.close();
    }
    
}
 

@Test
public void testPreparedGraphQuery()
	throws Exception
{
	testCon.add(alice, name, nameAlice, context2);
	testCon.add(alice, mbox, mboxAlice, context2);
	testCon.add(context2, publisher, nameAlice);
	testCon.add(bob, name, nameBob, context1);
	testCon.add(bob, mbox, mboxBob, context1);
	testCon.add(context1, publisher, nameBob);
	StringBuilder queryBuilder = new StringBuilder(128);
       queryBuilder.append(" prefix foaf: <" + FOAF_NS + ">");
	queryBuilder.append(" construct ");
	queryBuilder.append(" where { ?s foaf:name ?name . ?s foaf:mbox ?mbox . }");
	GraphQuery query = testCon.prepareGraphQuery(QueryLanguage.SPARQL, queryBuilder.toString());
	query.setBinding(NAME, nameBob);
	GraphQueryResult result = query.evaluate();
	try {
		assertThat(result, is(notNullValue()));
		assertThat(result.hasNext(), is(equalTo(true)));
		while (result.hasNext()) {
			Statement st = result.next();
			URI predicate = st.getPredicate();
			assertThat(predicate, anyOf(is(equalTo(name)), is(equalTo(mbox))));
			Value object = st.getObject();
			if (name.equals(predicate)) {
				assertEquals("unexpected value for name: " + object, nameBob, object);
			}
			else {
				assertThat(predicate, is(equalTo(mbox)));
				assertEquals("unexpected value for mbox: " + object, mboxBob, object);
			}
		}
	}
	finally {
		result.close();
	}
}
 

/**
 * Executes a given update command both on remote and local model.
 * 
 * @param data the object holding test data (i.e. commands, queries, datafiles).
 * @throws Exception hopefully never otherwise the corresponding test fails.
 */
@SuppressWarnings("deprecation")
void executeUpdate(final MisteryGuest data) throws Exception {
	load(data);
	
	final String updateCommand = readFile(data.query);
	final Update localUpdate = localConnection.prepareUpdate(QueryLanguage.SPARQL, updateCommand);
	final Update cumulusUpdate = cumulusConnection.prepareUpdate(QueryLanguage.SPARQL, updateCommand);
	
	localUpdate.execute();
	cumulusUpdate.execute();
	
	try {
		assertTrue(ModelUtil.equals(
				statements(localConnection.getStatements(null, null, null, false).asList()), 
				statements(cumulusConnection.getStatements(null, null, null, false).asList())));
		
	} catch (final AssertionError exception) {
		final String queryString = "CONSTRUCT {?s ?p ?o} WHERE {?s ?p ?o}";
		final GraphQuery localQuery = localConnection.prepareGraphQuery(QueryLanguage.SPARQL, queryString);
		final GraphQuery cumulusQuery = cumulusConnection.prepareGraphQuery(QueryLanguage.SPARQL, queryString);
		
		final GraphQueryResult debugLocalResult = localQuery.evaluate();
		final GraphQueryResult debugCumulusResult = cumulusQuery.evaluate();
			
		System.err.println("***** LOCAL ******");
		QueryResultIO.write(debugLocalResult, RDFFormat.NTRIPLES, System.err);

		System.err.println("***** CRDF ******");
		QueryResultIO.write(debugCumulusResult, RDFFormat.NTRIPLES, System.err);
		
		debugCumulusResult.close();
		debugLocalResult.close();
		throw exception;
	}
}
 

/**
 * Executes a given CONSTRUCT query against a given dataset.
 * 
 * @param data the mistery guest containing test data (query and dataset)
 * @throws Exception never, otherwise the test fails.
 */
protected void constructTest(final MisteryGuest data) throws Exception {
	load(data);
	
	final String queryString = queryString(data.query);
	final GraphQuery localQuery = localConnection.prepareGraphQuery(QueryLanguage.SPARQL, queryString);
	final GraphQuery cumulusQuery = cumulusConnection.prepareGraphQuery(QueryLanguage.SPARQL, queryString);
	
	GraphQueryResult localResult = localQuery.evaluate();
	GraphQueryResult cumulusResult = cumulusQuery.evaluate();
	try {
		assertTrue(
				ModelUtil.equals(
						statements(Iterations.asSet(localResult)), 
						statements(Iterations.asSet(cumulusResult))));			
	} catch (final AssertionError exception) {
		final GraphQueryResult debugLocalResult = localQuery.evaluate();
		final GraphQueryResult debugCumulusResult = cumulusQuery.evaluate();
			
		System.err.println("***** LOCAL ******");
		QueryResultIO.write(debugLocalResult, RDFFormat.NTRIPLES, System.err);

		System.err.println("***** CRDF ******");
		QueryResultIO.write(debugCumulusResult, RDFFormat.NTRIPLES, System.err);
		
		debugCumulusResult.close();
		debugLocalResult.close();
		throw exception;
	}
	
	cumulusResult.close();
	localResult.close();
}
 

@Override
public ClosableIterable<Statement> sparqlConstruct(String queryString)
        throws ModelRuntimeException {
	this.assertModel();
	GraphQuery query;
	try {
		query = this.connection.prepareGraphQuery(QueryLanguage.SPARQL, queryString);
		GraphQueryResult graphQueryResult = query.evaluate();
		return new StatementIterable(graphQueryResult, null);
	} catch(OpenRDFException e) {
		throw new ModelRuntimeException(e);
	}
}
 

@Override
public ClosableIterable<Statement> sparqlDescribe(String queryString)
        throws ModelRuntimeException {
	this.assertModel();
	GraphQuery query;
	try {
		query = this.connection.prepareGraphQuery(QueryLanguage.SPARQL, queryString);
		GraphQueryResult graphQueryResult = query.evaluate();
		return new StatementIterable(graphQueryResult, null);
	} catch(OpenRDFException e) {
		throw new ModelRuntimeException(e);
	}
}
 

public Model asModel() throws OpenRDFException {
	GraphQuery qry = prepareGraphQuery();
	Model model = new LinkedHashModel();
	qry.evaluate(new StatementCollector(model));
	return model;
}
 

public static void _main(String[] args) throws Exception {

        String sesameURL, repoID;
        
        if (args != null && args.length == 2) {
            sesameURL = args[0];
            repoID = args[1];
        } else {
            sesameURL = DemoSesameServer.sesameURL;
            repoID = DemoSesameServer.repoID;
        }
        
        Repository repo = new HTTPRepository(sesameURL, repoID);
        repo.initialize();
        
        RepositoryConnection cxn = repo.getConnection();
        cxn.setAutoCommit(false);
        
        try { // load some statements built up programmatically
            
            URI mike = new URIImpl(BD.NAMESPACE + "Mike");
            URI bryan = new URIImpl(BD.NAMESPACE + "Bryan");
            URI loves = new URIImpl(BD.NAMESPACE + "loves");
            URI rdf = new URIImpl(BD.NAMESPACE + "RDF");
            Graph graph = new GraphImpl();
            graph.add(mike, loves, rdf);
            graph.add(bryan, loves, rdf);
            
            cxn.add(graph);
            cxn.commit();
            
        } finally {
            
            cxn.close();
            
        }
        
        { // show the entire contents of the repository

            SparqlBuilder sparql = new SparqlBuilder();
            sparql.addTriplePattern("?s", "?p", "?o");
            
            GraphQuery query = cxn.prepareGraphQuery(
                    QueryLanguage.SPARQL, sparql.toString());
            GraphQueryResult result = query.evaluate();
            while (result.hasNext()) {
                Statement stmt = result.next();
                System.err.println(stmt);
            }
            
        }
        
        
    }