fix: Update relationship properties objects before populating result entities.

Closes #2904

Author: michael-simons

Diff for: src/main/java/org/springframework/data/neo4j/core/mapping/MappingSupport.java

@@ -179,6 +179,9 @@ public static Object getRelationshipOrRelationshipPropertiesObject(Neo4jMappingC
 			PersistentPropertyAccessor<Object> relationshipPropertiesAccessor = persistentEntity.getPropertyAccessor(relationshipPropertiesValue);
 			relationshipPropertiesAccessor.setProperty(persistentEntity.getPersistentProperty(TargetNode.class), newRelationshipObject);
 			newRelationshipObject = relationshipPropertiesAccessor.getBean();
+
+			// If we recreate or manipulate the object including it's accessor, we must update it in the holder as well.
+			entityHolder.setRelationshipProperties(newRelationshipObject);
 		}
 		return newRelationshipObject;
 	}
@@ -190,14 +193,17 @@ private MappingSupport() {}
 	 */
 	@API(status = API.Status.INTERNAL)
 	public final static class RelationshipPropertiesWithEntityHolder {
-		private final PersistentPropertyAccessor<?> relationshipPropertiesPropertyAccessor;
-		private final Object relationshipProperties;
+
+		private final Neo4jPersistentEntity<?> relationshipPropertiesEntity;
+		private PersistentPropertyAccessor<?> relationshipPropertiesPropertyAccessor;
+		private Object relationshipProperties;
 		private final Object relatedEntity;
 
 		RelationshipPropertiesWithEntityHolder(
 				Neo4jPersistentEntity<?> relationshipPropertiesEntity,
 				Object relationshipProperties, Object relatedEntity
 		) {
+			this.relationshipPropertiesEntity = relationshipPropertiesEntity;
 			this.relationshipPropertiesPropertyAccessor = relationshipPropertiesEntity.getPropertyAccessor(relationshipProperties);
 			this.relationshipProperties = relationshipProperties;
 			this.relatedEntity = relatedEntity;
@@ -211,6 +217,11 @@ public Object getRelationshipProperties() {
 			return relationshipProperties;
 		}
 
+		private void setRelationshipProperties(Object relationshipProperties) {
+			this.relationshipProperties = relationshipProperties;
+			this.relationshipPropertiesPropertyAccessor = relationshipPropertiesEntity.getPropertyAccessor(this.relationshipProperties);
+		}
+
 		public Object getRelatedEntity() {
 			return relatedEntity;
 		}
@@ -231,5 +242,12 @@ public boolean equals(Object o) {
 		public int hashCode() {
 			return Objects.hash(relationshipProperties, relatedEntity);
 		}
+
+		@Override
+		public String toString() {
+			return "RelationshipPropertiesWithEntityHolder{" +
+					"relationshipProperties=" + relationshipProperties +
+					'}';
+		}
 	}
 }

Diff for: src/test/java/org/springframework/data/neo4j/documentation/domain/MovieEntity.java

@@ -44,7 +44,7 @@ public class MovieEntity {
 
 	// tag::mapping.relationship.properties[]
 	@Relationship(type = "ACTED_IN", direction = Direction.INCOMING) // <.>
-	private List<Roles> actorsAndRoles;
+	private List<Roles> actorsAndRoles = new ArrayList<>();
 	// end::mapping.relationship.properties[]
 
 	@Relationship(type = "DIRECTED", direction = Direction.INCOMING)

Diff for: src/test/java/org/springframework/data/neo4j/documentation/domain/Roles.java

@@ -41,8 +41,21 @@ public Roles(PersonEntity person, List<String> roles) {
 		this.roles = roles;
 	}
 
+	// end::mapping.relationship.properties[]
+	public Long getId() {
+		return id;
+	}
+	// tag::mapping.relationship.properties[]
+
 	public List<String> getRoles() {
 		return roles;
 	}
+
+	@Override
+	public String toString() {
+		return "Roles{" +
+				"id=" + id +
+				'}' + this.hashCode();
+	}
 }
 // end::mapping.relationship.properties[]

Diff for: src/test/java/org/springframework/data/neo4j/documentation/spring_boot/TemplateExampleTest.java

@@ -23,24 +23,59 @@
 import java.util.Optional;
 
 // end::faq.template-imperative-pt1[]
-import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.BeforeEach;
 // tag::faq.template-imperative-pt1[]
 import org.junit.jupiter.api.Test;
+// end::faq.template-imperative-pt1[]
+import org.neo4j.driver.Driver;
+// tag::faq.template-imperative-pt1[]
 import org.springframework.beans.factory.annotation.Autowired;
+// end::faq.template-imperative-pt1[]
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.neo4j.core.DatabaseSelectionProvider;
+// tag::faq.template-imperative-pt1[]
 import org.springframework.data.neo4j.core.Neo4jTemplate;
+// end::faq.template-imperative-pt1[]
+import org.springframework.data.neo4j.core.transaction.Neo4jBookmarkManager;
+import org.springframework.data.neo4j.core.transaction.Neo4jTransactionManager;
+// tag::faq.template-imperative-pt1[]
 import org.springframework.data.neo4j.documentation.domain.MovieEntity;
 import org.springframework.data.neo4j.documentation.domain.PersonEntity;
 import org.springframework.data.neo4j.documentation.domain.Roles;
+// end::faq.template-imperative-pt1[]
+import org.springframework.data.neo4j.repository.config.EnableNeo4jRepositories;
+import org.springframework.data.neo4j.test.BookmarkCapture;
+import org.springframework.data.neo4j.test.Neo4jExtension;
+import org.springframework.data.neo4j.test.Neo4jImperativeTestConfiguration;
+import org.springframework.data.neo4j.test.Neo4jIntegrationTest;
+import org.springframework.transaction.PlatformTransactionManager;
+import org.springframework.transaction.annotation.EnableTransactionManagement;
+// tag::faq.template-imperative-pt1[]
 
 // end::faq.template-imperative-pt1[]
 
 /**
  * @author Michael J. Simons
  */
-@Disabled
+@Neo4jIntegrationTest
 // tag::faq.template-imperative-pt2[]
 public class TemplateExampleTest {
 
+	// end::faq.template-imperative-pt2[]
+
+	protected static Neo4jExtension.Neo4jConnectionSupport neo4jConnectionSupport;
+
+	@BeforeEach
+	void setup(@Autowired Driver driver, @Autowired BookmarkCapture bookmarkCapture) {
+		try (var session = driver.session(bookmarkCapture.createSessionConfig()); var transaction = session.beginTransaction()) {
+			transaction.run("MATCH (n) detach delete n").consume();
+			transaction.commit();
+			bookmarkCapture.seedWith(session.lastBookmarks());
+		}
+	}
+
+	// tag::faq.template-imperative-pt2[]
 	@Test
 	void shouldSaveAndReadEntities(@Autowired Neo4jTemplate neo4jTemplate) {
 
@@ -53,12 +88,45 @@ void shouldSaveAndReadEntities(@Autowired Neo4jTemplate neo4jTemplate) {
 		movie.getActorsAndRoles().add(roles1);
 		movie.getActorsAndRoles().add(roles2);
 
-		neo4jTemplate.save(movie);
+		MovieEntity result = neo4jTemplate.save(movie);
+		// end::mapping.relationship.properties[]
+		assertThat(result.getActorsAndRoles()).allSatisfy(relationship -> assertThat(relationship.getId()).isNotNull());
+		// tag::mapping.relationship.properties[]
 
 		Optional<PersonEntity> person = neo4jTemplate.findById("Dean Jones", PersonEntity.class);
 		assertThat(person).map(PersonEntity::getBorn).hasValue(1931);
 
 		assertThat(neo4jTemplate.count(PersonEntity.class)).isEqualTo(2L);
 	}
+
+	// end::faq.template-imperative-pt2[]
+	@Configuration
+	@EnableTransactionManagement
+	@EnableNeo4jRepositories(considerNestedRepositories = true)
+	static class Config extends Neo4jImperativeTestConfiguration {
+
+		@Bean
+		public Driver driver() {
+			return neo4jConnectionSupport.getDriver();
+		}
+
+		@Bean
+		public BookmarkCapture bookmarkCapture() {
+			return new BookmarkCapture();
+		}
+
+		@Override
+		public PlatformTransactionManager transactionManager(Driver driver, DatabaseSelectionProvider databaseNameProvider) {
+
+			BookmarkCapture bookmarkCapture = bookmarkCapture();
+			return new Neo4jTransactionManager(driver, databaseNameProvider, Neo4jBookmarkManager.create(bookmarkCapture));
+		}
+
+		@Override
+		public boolean isCypher5Compatible() {
+			return neo4jConnectionSupport.isCypher5SyntaxCompatible();
+		}
+	}
+	// tag::faq.template-imperative-pt2[]
 }
 // end::faq.template-imperative-pt2[]