Add support for limiting keywords in derived query methods.

spring-data-neo4j/src/main/java/org/springframework/data/neo4j/core/cypher/DefaultStatementBuilder.java

@@ -27,6 +27,7 @@ import org.springframework.data.neo4j.core.cypher.StatementBuilder.OngoingMatch;
 import org.springframework.data.neo4j.core.cypher.StatementBuilder.OngoingMatchWithWhere;
 import org.springframework.data.neo4j.core.cypher.StatementBuilder.OngoingMatchWithoutWhere;
 import org.springframework.data.neo4j.core.cypher.support.Visitable;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -225,14 +226,20 @@ class DefaultStatementBuilder
 		}
 
 		@Override
-		public final OngoingMatchAndReturn skip(Number number) {
-			skip = Skip.of(number);
+		public final OngoingMatchAndReturn skip(@Nullable Number number) {
+
+			if (number != null) {
+				skip = Skip.create(number);
+			}
 			return this;
 		}
 
 		@Override
-		public final OngoingMatchAndReturn limit(Number number) {
-			limit = Limit.of(number);
+		public final OngoingMatchAndReturn limit(@Nullable Number number) {
+
+			if (number != null) {
+				limit = Limit.create(number);
+			}
 			return this;
 		}
 

spring-data-neo4j/src/main/java/org/springframework/data/neo4j/core/cypher/Limit.java

@@ -21,6 +21,7 @@ package org.springframework.data.neo4j.core.cypher;
 import org.apiguardian.api.API;
 import org.springframework.data.neo4j.core.cypher.support.Visitable;
 import org.springframework.data.neo4j.core.cypher.support.Visitor;
+import org.springframework.util.Assert;
 
 /**
  * @author Gerrit Meier
@@ -30,7 +31,10 @@ import org.springframework.data.neo4j.core.cypher.support.Visitor;
 @API(status = API.Status.INTERNAL, since = "1.0")
 public final class Limit implements Visitable {
 
-	public static Limit of(Number value) {
+	static Limit create(Number value) {
+
+		Assert.notNull(value, "A limit cannot have a null value.");
+
 		return new Limit(new NumberLiteral(value));
 	}
 
@@ -44,5 +48,6 @@ public final class Limit implements Visitable {
 	public void accept(Visitor visitor) {
 		visitor.enter(this);
 		limitAmount.accept(visitor);
+		visitor.leave(this);
 	}
 }

spring-data-neo4j/src/main/java/org/springframework/data/neo4j/core/cypher/Skip.java

@@ -21,6 +21,7 @@ package org.springframework.data.neo4j.core.cypher;
 import org.apiguardian.api.API;
 import org.springframework.data.neo4j.core.cypher.support.Visitable;
 import org.springframework.data.neo4j.core.cypher.support.Visitor;
+import org.springframework.util.Assert;
 
 /**
  * @author Gerrit Meier
@@ -30,7 +31,10 @@ import org.springframework.data.neo4j.core.cypher.support.Visitor;
 @API(status = API.Status.INTERNAL, since = "1.0")
 public final class Skip implements Visitable {
 
-	public static Skip of(Number value) {
+	static Skip create(Number value) {
+
+		Assert.notNull(value, "Cannot skip a value of null.");
+
 		return new Skip(new NumberLiteral(value));
 	}
 
@@ -44,5 +48,6 @@ public final class Skip implements Visitable {
 	public void accept(Visitor visitor) {
 		visitor.enter(this);
 		skipAmount.accept(visitor);
+		visitor.leave(this);
 	}
 }

spring-data-neo4j/src/main/java/org/springframework/data/neo4j/core/cypher/StatementBuilder.java

@@ -19,6 +19,7 @@
 package org.springframework.data.neo4j.core.cypher;
 
 import org.apiguardian.api.API;
+import org.springframework.lang.Nullable;
 
 /**
  * @author Michael J. Simons
@@ -236,10 +237,10 @@ public interface StatementBuilder {
 		/**
 		 * Adds a skip clause, skipping the given number of records.
 		 *
-		 * @param number How many records to skip
-		 * @return A step that only allows the limit of records to be specified
+		 * @param number How many records to skip. If this is null, then no records are skipped.
+		 * @return A step that only allows the limit of records to be specified.
 		 */
-		ExposesLimit skip(Number number);
+		ExposesLimit skip(@Nullable Number number);
 
 	}
 
@@ -250,10 +251,10 @@ public interface StatementBuilder {
 
 		/**
 		 * Limits the number of returned records.
-		 * @param number How many records to return
-		 * @return A buildable match statement
+		 * @param number How many records to return. If this is null, all the records are returned.
+		 * @return A buildable match statement.
 		 */
-		BuildableMatch limit(Number number);
+		BuildableMatch limit(@Nullable Number number);
 	}
 
 	/**

spring-data-neo4j/src/main/java/org/springframework/data/neo4j/repository/query/CypherQueryCreator.java

@@ -79,6 +79,11 @@ final class CypherQueryCreator extends AbstractQueryCreator<String, Condition> {
 	private Iterator<Neo4jParameter> formalParameters;
 	private final Queue<Parameter> lastParameter = new LinkedList<>();
 
+	/**
+	 * Stores the number of max results, if the {@link PartTree tree} is limiting.
+	 */
+	private final Number maxResults;
+
 	/**
 	 * Sort items may already be needed for some parts, i.e. of type NEAR.
 	 */
@@ -93,6 +98,7 @@ final class CypherQueryCreator extends AbstractQueryCreator<String, Condition> {
 		this.domainType = domainType;
 		this.nodeDescription = this.mappingContext.getRequiredNodeDescription(this.domainType);
 		this.formalParameters = formalParameters.iterator();
+		this.maxResults = tree.isLimiting() ? tree.getMaxResults() : null;
 	}
 
 	@Override
@@ -127,6 +133,7 @@ final class CypherQueryCreator extends AbstractQueryCreator<String, Condition> {
 					sort.stream().map(sortAdapterFor(nodeDescription))
 				).toArray(SortItem[]::new)
 			)
+			.limit(maxResults)
 			.build();
 
 		return CypherRenderer.create().render(statement);

spring-data-neo4j/src/main/java/org/springframework/data/neo4j/repository/query/PartTreeNeo4jQuery.java

@@ -105,6 +105,7 @@ final class PartTreeNeo4jQuery extends AbstractNeo4jQuery {
 			mappingContext, domainType, tree, formalParameters, actualParameters
 		);
 
+
 		String cypherQuery = queryCreator.createQuery();
 		Map<String, Object> boundedParameters = formalParameters
 			.getBindableParameters().stream()

spring-data-neo4j/src/test/java/org/springframework/data/neo4j/core/cypher/CypherTest.java

@@ -241,6 +241,15 @@ public class CypherTest {
 						"MATCH (u:`User`) RETURN u SKIP 1");
 			}
 
+			@Test
+			void nullSkip() {
+				Statement statement = Cypher.match(userNode).returning(userNode).skip(null).build();
+
+				assertThat(cypherRenderer.render(statement))
+					.isEqualTo(
+						"MATCH (u:`User`) RETURN u");
+			}
+
 			@Test
 			void limit() {
 				Statement statement = Cypher.match(userNode).returning(userNode).limit(1).build();
@@ -250,6 +259,15 @@ public class CypherTest {
 						"MATCH (u:`User`) RETURN u LIMIT 1");
 			}
 
+			@Test
+			void nullLimit() {
+				Statement statement = Cypher.match(userNode).returning(userNode).limit(null).build();
+
+				assertThat(cypherRenderer.render(statement))
+					.isEqualTo(
+						"MATCH (u:`User`) RETURN u");
+			}
+
 			@Test
 			void skipAndLimit() {
 				Statement statement = Cypher.match(userNode).returning(userNode).skip(1).limit(1).build();
@@ -259,6 +277,16 @@ public class CypherTest {
 						"MATCH (u:`User`) RETURN u SKIP 1 LIMIT 1");
 			}
 
+			@Test
+			void nullskipAndLimit() {
+				Statement statement = Cypher.match(userNode).returning(userNode).skip(null).limit(null).build();
+
+				assertThat(cypherRenderer.render(statement))
+					.isEqualTo(
+						"MATCH (u:`User`) RETURN u");
+			}
+
+
 			@Test
 			void distinct() {
 				Statement statement = Cypher.match(userNode).returningDistinct(userNode).skip(1).limit(1).build();

spring-data-neo4j/src/test/java/org/springframework/data/neo4j/integration/RepositoryIT.java

@@ -26,6 +26,7 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
+import java.util.stream.IntStream;
 
 import org.assertj.core.groups.Tuple;
 import org.junit.jupiter.api.BeforeEach;
@@ -125,6 +126,10 @@ class RepositoryIT {
 		transaction.run("CREATE (n:PersonWithWither) SET n.name = '" + TEST_PERSON1_NAME + "'");
 		transaction.run("CREATE (n:KotlinPerson) SET n.name = '" + TEST_PERSON1_NAME + "'");
 		transaction.run("CREATE (a:Thing {theId: 'anId', name: 'Homer'})");
+
+		IntStream.rangeClosed(1, 20).forEach(i ->
+			transaction.run("CREATE (a:Thing {theId: 'id' + $i, name: 'name' + $i})", Values.parameters("i", String.format("%02d", i))));
+
 		transaction.success();
 		transaction.close();
 
@@ -784,13 +789,30 @@ class RepositoryIT {
 			.containsExactly(person1);
 	}
 
+	@Test
+	void limitClauseShouldWork() {
+
+		List<ThingWithAssignedId> things;
+
+		things = thingRepository.findTop5ByOrderByNameDesc();
+		assertThat(things)
+			.hasSize(5)
+			.extracting(ThingWithAssignedId::getName)
+			.containsExactlyInAnyOrder("name20", "name19", "name18", "name17", "name16");
+
+		things = thingRepository.findFirstByOrderByNameDesc();
+		assertThat(things)
+			.extracting(ThingWithAssignedId::getName)
+			.containsExactlyInAnyOrder("name20");
+	}
+
 	@Configuration
 	@EnableNeo4jRepositories
 	@EnableTransactionManagement
 	static class Config {
 
 		@Bean
-		public Driver driver() {
+		public static Driver driver() {
 
 			return neo4jConnectionSupport.openConnection();
 		}

spring-data-neo4j/src/test/java/org/springframework/data/neo4j/integration/ThingRepository.java

@@ -18,10 +18,15 @@
  */
 package org.springframework.data.neo4j.integration;
 
+import java.util.List;
+
 import org.springframework.data.repository.CrudRepository;
 
 /**
  * @author Michael J. Simons
  */
 public interface ThingRepository extends CrudRepository<ThingWithAssignedId, String> {
+	List<ThingWithAssignedId> findFirstByOrderByNameDesc();
+
+	List<ThingWithAssignedId> findTop5ByOrderByNameDesc();
 }