GH-2326 - Fall back to individual statements when a heterogeneous

collection is persisted.

In case a heterogeneous is persisted via `saveAll` on a repository or
any of the templates, we do fall back to individual statements to
persist its content the same way we handle dynamic labels, versioned
entities or entities with generated ids.

The reason for this is simple: We need the exact entity to determine
labels in an inheritance hierachy, otherwise only the information given
by the lowest common denominator will be considered, effectively leading
to `saveAll` behaving different than `save`.

This fixes #2326.

Author: michael-simons

src/main/java/org/springframework/data/neo4j/core/Neo4jTemplate.java

@@ -297,22 +297,21 @@ public <T> List<T> saveAll(Iterable<T> instances) {
 
 		String databaseName = getDatabaseName();
 
-		List<T> entities;
-		if (instances instanceof Collection) {
-			entities = new ArrayList<>((Collection<T>) instances);
-		} else {
-			entities = new ArrayList<>();
-			instances.forEach(entities::add);
-		}
+		Set<Class<?>> types = new HashSet<>();
+		List<T> entities = new ArrayList<>();
+		instances.forEach(instance -> {
+			entities.add(instance);
+			types.add(instance.getClass());
+		});
 
 		if (entities.isEmpty()) {
 			return Collections.emptyList();
 		}
 
-		Class<T> domainClass = (Class<T>) TemplateSupport.findCommonElementType(entities);
-		Assert.notNull(domainClass, "Could not determine common domain class to save.");
-		Neo4jPersistentEntity<?> entityMetaData = neo4jMappingContext.getPersistentEntity(domainClass);
-		if (entityMetaData.isUsingInternalIds() || entityMetaData.hasVersionProperty()
+		boolean heterogeneousCollection = types.size() > 1;
+		Class<T> domainClass = (Class<T>) types.iterator().next();
+		Neo4jPersistentEntity<?> entityMetaData = neo4jMappingContext.getRequiredPersistentEntity(domainClass);
+		if (heterogeneousCollection || entityMetaData.isUsingInternalIds() || entityMetaData.hasVersionProperty()
 				|| entityMetaData.getDynamicLabelsProperty().isPresent()) {
 			log.debug("Saving entities using single statements.");
 
@@ -332,7 +331,7 @@ class Tuple3<T> {
 		}
 
 		List<Tuple3<T>> entitiesToBeSaved = entities.stream()
-				.map(e -> new Tuple3<>(e, neo4jMappingContext.getPersistentEntity(e.getClass()).isNew(e), eventSupport.maybeCallBeforeBind(e)))
+				.map(e -> new Tuple3<>(e, entityMetaData.isNew(e), eventSupport.maybeCallBeforeBind(e)))
 				.collect(Collectors.toList());
 
 		// Save roots

src/main/java/org/springframework/data/neo4j/core/ReactiveNeo4jTemplate.java

@@ -28,6 +28,7 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
@@ -293,24 +294,22 @@ private <T> Mono<Tuple2<T, DynamicLabels>> determineDynamicLabels(T entityToBeSa
 	@Override
 	public <T> Flux<T> saveAll(Iterable<T> instances) {
 
-		List<T> entities;
-		if (instances instanceof Collection) {
-			entities = new ArrayList<>((Collection<T>) instances);
-		} else {
-			entities = new ArrayList<>();
-			instances.forEach(entities::add);
-		}
+		Set<Class<?>> types = new HashSet<>();
+		List<T> entities = new ArrayList<>();
+		instances.forEach(instance -> {
+			entities.add(instance);
+			types.add(instance.getClass());
+		});
 
 		if (entities.isEmpty()) {
 			return Flux.empty();
 		}
 
-		Class<T> domainClass = (Class<T>) TemplateSupport.findCommonElementType(entities);
-		Assert.notNull(domainClass, "Could not determine common domain class to save.");
-		Neo4jPersistentEntity<?> entityMetaData = neo4jMappingContext.getPersistentEntity(domainClass);
-
-		if (entityMetaData.isUsingInternalIds() || entityMetaData.hasVersionProperty()
-				|| entityMetaData.getDynamicLabelsProperty().isPresent()) {
+		boolean heterogeneousCollection = types.size() > 1;
+		Class<T> domainClass = (Class<T>) types.iterator().next();
+		Neo4jPersistentEntity<?> entityMetaData = neo4jMappingContext.getRequiredPersistentEntity(domainClass);
+		if (heterogeneousCollection || entityMetaData.isUsingInternalIds() || entityMetaData.hasVersionProperty()
+			|| entityMetaData.getDynamicLabelsProperty().isPresent()) {
 			log.debug("Saving entities using single statements.");
 
 			return getDatabaseName().flatMapMany(

src/test/java/org/springframework/data/neo4j/integration/issues/gh2326/Animal.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2011-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.integration.issues.gh2326;
+
+import org.springframework.data.neo4j.core.schema.Node;
+
+/**
+ * @author Michael J. Simons
+ */
+@Node
+public abstract class Animal extends BaseEntity {
+
+	/**
+	 * Provides label `Pet`
+	 */
+	@Node
+	public static abstract class Pet extends Animal {
+
+		/**
+		 * Provides label `Cat`
+		 */
+		@Node
+		public static class Cat extends Pet {
+		}
+
+		/**
+		 * Provides label `Dog`
+		 */
+		@Node
+		public static class Dog extends Pet {
+		}
+	}
+}

src/test/java/org/springframework/data/neo4j/integration/issues/gh2326/BaseEntity.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2011-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.integration.issues.gh2326;
+
+import org.springframework.data.neo4j.core.schema.GeneratedValue;
+import org.springframework.data.neo4j.core.schema.Id;
+import org.springframework.data.neo4j.core.support.UUIDStringGenerator;
+
+/**
+ * @author Michael J. Simons
+ */
+public abstract class BaseEntity {
+
+	@Id @GeneratedValue(UUIDStringGenerator.class)
+	private String id;
+
+	public String getId() {
+		return id;
+	}
+}

src/test/java/org/springframework/data/neo4j/integration/issues/gh2326/GH2326IT.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2011-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.integration.issues.gh2326;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.Test;
+import org.neo4j.driver.Driver;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.neo4j.config.AbstractNeo4jConfig;
+import org.springframework.data.neo4j.repository.Neo4jRepository;
+import org.springframework.data.neo4j.repository.config.EnableNeo4jRepositories;
+import org.springframework.data.neo4j.test.Neo4jIntegrationTest;
+import org.springframework.transaction.annotation.EnableTransactionManagement;
+
+/**
+ * @author Michael J. Simons
+ */
+@Neo4jIntegrationTest
+class GH2326IT extends TestBase {
+
+	@Test // GH-2326
+	void saveShouldAddAllLabels(@Autowired AnimalRepository animalRepository) {
+
+		List<Animal> animals = Arrays.asList(new Animal.Pet.Cat(), new Animal.Pet.Dog());
+		List<String> ids = animals.stream().map(animalRepository::save).map(BaseEntity::getId)
+				.collect(Collectors.toList());
+
+		assertLabels(ids);
+	}
+
+	@Test // GH-2326
+	void saveAllShouldAddAllLabels(@Autowired AnimalRepository animalRepository) {
+
+		List<Animal> animals = Arrays.asList(new Animal.Pet.Cat(), new Animal.Pet.Dog());
+		List<String> ids = animalRepository.saveAll(animals).stream().map(BaseEntity::getId)
+				.collect(Collectors.toList());
+
+		assertLabels(ids);
+	}
+
+	public interface AnimalRepository extends Neo4jRepository<Animal, String> {
+	}
+
+	@Configuration
+	@EnableTransactionManagement
+	@EnableNeo4jRepositories(considerNestedRepositories = true)
+	static class Config extends AbstractNeo4jConfig {
+
+		@Bean
+		public Driver driver() {
+
+			return neo4jConnectionSupport.getDriver();
+		}
+	}
+}

src/test/java/org/springframework/data/neo4j/integration/issues/gh2326/ReactiveGH2326IT.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2011-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.integration.issues.gh2326;
+
+import reactor.core.publisher.Flux;
+import reactor.test.StepVerifier;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+import org.neo4j.driver.Driver;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.neo4j.config.AbstractReactiveNeo4jConfig;
+import org.springframework.data.neo4j.repository.ReactiveNeo4jRepository;
+import org.springframework.data.neo4j.repository.config.EnableReactiveNeo4jRepositories;
+import org.springframework.data.neo4j.test.Neo4jIntegrationTest;
+import org.springframework.transaction.annotation.EnableTransactionManagement;
+
+/**
+ * @author Michael J. Simons
+ */
+@Neo4jIntegrationTest
+class ReactiveGH2326IT extends TestBase {
+
+	@Test // GH-2326
+	void saveShouldAddAllLabels(@Autowired AnimalRepository animalRepository) {
+
+		List<String> ids = new ArrayList<>();
+		List<Animal> animals = Arrays.asList(new Animal.Pet.Cat(), new Animal.Pet.Dog());
+		Flux.fromIterable(animals).flatMap(animalRepository::save)
+				.map(BaseEntity::getId)
+				.as(StepVerifier::create)
+				.recordWith(() -> ids)
+				.expectNextCount(2)
+				.verifyComplete();
+
+		assertLabels(ids);
+	}
+
+	@Test // GH-2326
+	void saveAllShouldAddAllLabels(@Autowired AnimalRepository animalRepository) {
+
+		List<String> ids = new ArrayList<>();
+		List<Animal> animals = Arrays.asList(new Animal.Pet.Cat(), new Animal.Pet.Dog());
+		animalRepository.saveAll(animals)
+				.map(BaseEntity::getId)
+				.as(StepVerifier::create)
+				.recordWith(() -> ids)
+				.expectNextCount(2)
+				.verifyComplete();
+
+		assertLabels(ids);
+	}
+
+	public interface AnimalRepository extends ReactiveNeo4jRepository<Animal, String> {
+	}
+
+	@Configuration
+	@EnableTransactionManagement
+	@EnableReactiveNeo4jRepositories(considerNestedRepositories = true)
+	static class Config extends AbstractReactiveNeo4jConfig {
+
+		@Bean
+		public Driver driver() {
+
+			return neo4jConnectionSupport.getDriver();
+		}
+	}
+}

src/test/java/org/springframework/data/neo4j/integration/issues/gh2326/TestBase.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2011-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.neo4j.integration.issues.gh2326;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.neo4j.driver.Session;
+import org.neo4j.driver.Transaction;
+import org.neo4j.driver.Value;
+import org.springframework.data.neo4j.test.Neo4jExtension;
+
+/**
+ * @author Michael J. Simons
+ */
+abstract class TestBase {
+
+	protected static Neo4jExtension.Neo4jConnectionSupport neo4jConnectionSupport;
+
+	@BeforeAll
+	protected static void setupData() {
+		try (Session session = neo4jConnectionSupport.getDriver().session();
+				Transaction transaction = session.beginTransaction();
+		) {
+			transaction.run("MATCH (n) detach delete n");
+			transaction.commit();
+		}
+	}
+
+	protected static void assertLabels(List<String> ids) {
+		try (Session session = neo4jConnectionSupport.getDriver().session()) {
+			for (String id : ids) {
+				List<String> labels = session.readTransaction(
+						tx -> tx.run("MATCH (n) WHERE n.id = $id RETURN labels(n)", Collections.singletonMap("id", id))
+								.single().get(0).asList(
+										Value::asString));
+				assertThat(labels)
+						.hasSize(3)
+						.contains("Animal", "Pet")
+						.containsAnyOf("Dog", "Cat");
+
+			}
+		}
+	}
+}