GH-4999: improve UpdateWithModelBuilder to support statement removal

Author: fkleedorfer

spring-components/rdf4j-spring/src/main/java/org/eclipse/rdf4j/spring/dao/support/UpdateWithModelBuilder.java

@@ -13,27 +13,38 @@
 
 import java.io.StringWriter;
 import java.lang.invoke.MethodHandles;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.List;
+import java.util.*;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
 import org.apache.commons.lang3.ObjectUtils;
-import org.eclipse.rdf4j.model.BNode;
-import org.eclipse.rdf4j.model.IRI;
-import org.eclipse.rdf4j.model.Model;
-import org.eclipse.rdf4j.model.Namespace;
-import org.eclipse.rdf4j.model.Resource;
-import org.eclipse.rdf4j.model.Statement;
+import org.eclipse.rdf4j.model.*;
+import org.eclipse.rdf4j.model.base.AbstractStatement;
+import org.eclipse.rdf4j.model.impl.LinkedHashModel;
 import org.eclipse.rdf4j.model.util.ModelBuilder;
+import org.eclipse.rdf4j.query.Operation;
 import org.eclipse.rdf4j.repository.RepositoryConnection;
 import org.eclipse.rdf4j.rio.RDFFormat;
 import org.eclipse.rdf4j.rio.Rio;
+import org.eclipse.rdf4j.spring.support.RDF4JTemplate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
+ * <p>
+ * An {@link Operation} that holds a {@link Model} internally and exposes a {@link ModelBuilder} for adding to it.
+ * Moreover it allows for deleting statements.
+ * </p>
+ * <p>
+ * Thus, the class provides a way of configuring an update to the repository incrementally, and no repository access
+ * happens until {@link #execute()} is called. (unless the client uses {@link #applyToConnection(Function)} and accesses
+ * the repository that way.)
+ * </p>
+ * Removing statements via {@link #remove} will remove them from the repository when {@link #execute()} is called;
+ * moreover, the statements will also be removed from the model at the time of the {@link #remove} call, such that a
+ * subsequent creation of some of the deleted statements to the model will result in those triples being first deleted
+ * and then added to the repository when {@link #execute()} is called.
+ *
  * @author Florian Kleedorfer
  * @since 4.0.0
  */
@@ -42,11 +53,55 @@ public class UpdateWithModelBuilder {
 	private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
 	private final RepositoryConnection con;
+
+	/** the model builder being exposed to clients */
 	private final ModelBuilder modelBuilder;
+	/** the model being built by the modelBuilder, and that is going to be added to the repository eventually */
+	private final Model addModel;
+
+	/**
+	 * Set of Statements to be removed from the repository eventually. The Statement implementation used here is the
+	 * {@link WildcardAllowingStatement}, which allows for using wildcards for deletion
+	 */
+	private final Set<Statement> removeStatements;
 
 	public UpdateWithModelBuilder(RepositoryConnection con) {
 		this.con = con;
-		this.modelBuilder = new ModelBuilder();
+		this.addModel = new LinkedHashModel();
+		this.removeStatements = new HashSet<>();
+		this.modelBuilder = new ModelBuilder(addModel);
+	}
+
+	public static UpdateWithModelBuilder fromTemplate(RDF4JTemplate template) {
+		return template.applyToConnection(con -> new UpdateWithModelBuilder(con));
+	}
+
+	/**
+	 * Will remove statements upon update execution, before processing any additions. Statements that are removed here
+	 * are also removed from the #addModel at the time of this call (not upon update execution)
+	 *
+	 * <p>
+	 * The semantics of {@link RepositoryConnection#remove(Iterable, Resource...)} apply, i.e. the resource(s) specified
+	 * here are used there, if any.
+	 *
+	 * @param subject   the subject, or null to match any resource
+	 * @param predicate the predicate, or null to match any IRI
+	 * @param object    the object, or null to match any value
+	 * @param resources the context(s), if any
+	 * @return this builder
+	 */
+	public UpdateWithModelBuilder remove(
+			Resource subject, IRI predicate, Value object, Resource... resources) {
+		addModel.remove(subject, predicate, object, resources);
+		if (resources.length == 0) {
+			removeStatements.add(new WildcardAllowingStatement(subject, predicate, object, null));
+		} else {
+			for (int i = 0; i < resources.length; i++) {
+				removeStatements.add(
+						new WildcardAllowingStatement(subject, predicate, object, resources[i]));
+			}
+		}
+		return this;
 	}
 
 	public UpdateWithModelBuilder setNamespace(Namespace ns) {
@@ -171,9 +226,63 @@ public void execute() {
 		Model model = modelBuilder.build();
 		if (logger.isDebugEnabled()) {
 			StringWriter sw = new StringWriter();
+			Rio.write(this.removeStatements, sw, RDFFormat.TURTLE);
+			logger.debug("removing the following triples:\n{}", sw.toString());
+			sw = new StringWriter();
 			Rio.write(model, sw, RDFFormat.TURTLE);
 			logger.debug("adding the following triples:\n{}", sw.toString());
 		}
-		con.add(model);
+		con.remove(this.removeStatements);
+		con.add(this.addModel);
+	}
+
+	static class WildcardAllowingStatement extends AbstractStatement {
+		private static final long serialVersionUID = -4116676621136121342L;
+		private final Resource subject;
+		private final IRI predicate;
+		private final Value object;
+		private final Resource context;
+
+		WildcardAllowingStatement(Resource subject, IRI predicate, Value object, Resource context) {
+			this.subject = subject;
+			this.predicate = predicate;
+			this.object = object;
+			this.context = context;
+		}
+
+		public Resource getSubject() {
+			return this.subject;
+		}
+
+		public IRI getPredicate() {
+			return this.predicate;
+		}
+
+		public Value getObject() {
+			return this.object;
+		}
+
+		public Resource getContext() {
+			return this.context;
+		}
+
+		@Override
+		public boolean equals(Object o) {
+			if (this == o)
+				return true;
+			if (o == null || getClass() != o.getClass())
+				return false;
+			WildcardAllowingStatement that = (WildcardAllowingStatement) o;
+			return Objects.equals(getSubject(), that.getSubject())
+					&& Objects.equals(getPredicate(), that.getPredicate())
+					&& Objects.equals(getObject(), that.getObject())
+					&& Objects.equals(getContext(), that.getContext());
+		}
+
+		@Override
+		public int hashCode() {
+			return Objects.hash(
+					super.hashCode(), getSubject(), getPredicate(), getObject(), getContext());
+		}
 	}
 }

spring-components/rdf4j-spring/src/test/java/org/eclipse/rdf4j/spring/dao/support/ServiceLayerTests.java

@@ -19,6 +19,7 @@
 
 import org.eclipse.rdf4j.spring.RDF4JSpringTestBase;
 import org.eclipse.rdf4j.spring.domain.model.Artist;
+import org.eclipse.rdf4j.spring.domain.model.EX;
 import org.eclipse.rdf4j.spring.domain.model.Painting;
 import org.eclipse.rdf4j.spring.domain.service.ArtService;
 import org.eclipse.rdf4j.spring.support.RDF4JTemplate;
@@ -63,6 +64,19 @@ public void testCreatePainting() {
 		assertTrue(painting.getId().toString().startsWith("urn:uuid"));
 	}
 
+	@Test
+	public void testChangeArtist() {
+		Artist artist = artService.createArtist("Jan", "Vermeer");
+		Painting painting = artService.createPainting("Cypresses", "oil on canvas", artist.getId());
+		assertNotNull(painting.getId());
+		assertTrue(painting.getId().toString().startsWith("urn:uuid"));
+		assertEquals(artist.getId(), painting.getArtistId());
+		artService.changeArtist(painting.getId(), EX.VanGogh);
+		painting = artService.getPainting(painting.getId());
+		assertNotNull(painting);
+		assertEquals(EX.VanGogh, painting.getArtistId());
+	}
+
 	@Test
 	public void testCreatePaintingWithoutArtist() {
 		assertThrows(NullPointerException.class, () -> artService.createPainting(
@@ -71,7 +85,6 @@ public void testCreatePaintingWithoutArtist() {
 				null));
 	}
 
-	// TODO
 	@Test
 	public void testRollbackOnException() {
 		transactionTemplate.execute(status -> {

spring-components/rdf4j-spring/src/test/java/org/eclipse/rdf4j/spring/domain/dao/PaintingDao.java

@@ -22,6 +22,7 @@
 import org.eclipse.rdf4j.query.BindingSet;
 import org.eclipse.rdf4j.sparqlbuilder.core.query.Queries;
 import org.eclipse.rdf4j.spring.dao.SimpleRDF4JCRUDDao;
+import org.eclipse.rdf4j.spring.dao.support.UpdateWithModelBuilder;
 import org.eclipse.rdf4j.spring.dao.support.bindingsBuilder.MutableBindings;
 import org.eclipse.rdf4j.spring.dao.support.sparql.NamedSparqlSupplier;
 import org.eclipse.rdf4j.spring.domain.model.EX;
@@ -97,4 +98,11 @@ protected IRI getInputId(Painting painting) {
 		}
 		return painting.getId();
 	}
+
+	public void changeArtist(IRI painting, IRI newArtist) {
+		UpdateWithModelBuilder update = getRdf4JTemplate().updateWithBuilder();
+		update.remove(null, EX.creatorOf, painting);
+		update.add(newArtist, EX.creatorOf, painting);
+		update.execute();
+	}
 }

spring-components/rdf4j-spring/src/test/java/org/eclipse/rdf4j/spring/domain/service/ArtService.java

@@ -29,6 +29,16 @@ public class ArtService {
 	@Autowired
 	private PaintingDao paintingDao;
 
+	@Transactional
+	public Artist getArtist(IRI id) {
+		return this.artistDao.getById(id);
+	}
+
+	@Transactional
+	public Painting getPainting(IRI id) {
+		return this.paintingDao.getById(id);
+	}
+
 	@Transactional(propagation = Propagation.REQUIRED)
 	public Artist createArtist(String firstName, String lastName) {
 		Artist artist = new Artist();
@@ -46,4 +56,9 @@ public Painting createPainting(String title, String technique, IRI artist) {
 		return paintingDao.save(painting);
 	}
 
+	@Transactional(propagation = Propagation.REQUIRED)
+	public void changeArtist(IRI painting, IRI newArtist) {
+		paintingDao.changeArtist(painting, newArtist);
+	}
+
 }