Hi Martin,
There's nothing the API IIRC.
The crude way is to write out to byte array and parse it.
Here's my (limited testing) attempt: I chose to work with the Graph API
because if you use the Model API there is both up and down casting to
match new Statement(Resources, Predicate, RDFNode).
------------------------
public static void main(String... args) {
Model mSrc = ModelFactory.createDefaultModel();
RDFDataMgr.read(mSrc, "some-suitable-test-data.nt");
Model mDst = ModelFactory.createDefaultModel();
Map<Node,Node> map = new HashMap<>();
Iter.asStream(mSrc.getGraph().find(Triple.ANY))
.map(t->clone(map, t))
.forEach(mDst.getGraph()::add);
// The N-triples writer uses the internal ID for the label.
RDFDataMgr.write(System.out, mSrc, Lang.NT);
System.out.println("----");
RDFDataMgr.write(System.out, mDst, Lang.NT);
}
public static Triple clone(Map<Node,Node> map, Triple t) {
return Triple.create(clone(map, t.getSubject()),
clone(map, t.getPredicate()),
clone(map, t.getObject()));
}
public static Node clone(Map<Node,Node> map, Node n) {
if ( ! n.isBlank() )
return n;
// Just (_)-> in Java9
return map.computeIfAbsent(n, NodeFactory::createBlankNode);
}
On 02/06/17 17:14, Martin G. Skjæveland wrote:
Hi,
I would like a method Model clone (Model) that creates a copy of a
model such that any blank nodes in the copy are kept apart from the source.
The test case below illustrates the intended use: adding the clone of a
model back into the model should increase the size of the model, if the
model contains blank nodes.
Is there such a method in the API, or need I invent my own? If so, any
suggestion of an optimal way will be greatly appreciated.
I have tried by adding a model into a fresh model. My other suggestions
are to iterate over all blank nodes in a model and replace all instances
with a fresh node, or to use a SPARQL query CONSTRUCT { ?s ?p ?o } WHERE
{ ?s ?p ?o }.
Thanks!
Martin
import static org.junit.Assert.*;
import org.apache.jena.rdf.model.Model;
import org.apache.jena.rdf.model.ModelFactory;
import org.apache.jena.rdf.model.ResourceFactory;
import org.apache.jena.vocabulary.OWL;
import org.apache.jena.vocabulary.RDF;
import org.junit.Test;
public class ModelsTest {
@Test
public void shouldCloneModel () {
// create the model: [] a Thing .
Model source = ModelFactory.createDefaultModel();
source.add(ResourceFactory.createResource(), RDF.type, OWL.Thing);
// OK
assertEquals(1, source.size());
// clone
Model copy = clone(source);
// OK
assertEquals(1, copy.size());
// adding cloned copy back into source
source.add(copy);
// Fails with current implementation
assertEquals(2, source.size());
}
public Model clone (Model source) {
Model copy = ModelFactory.createDefaultModel();
copy.add(source);
return copy;
}
}
