How to use Neo4J native types with SDN and OGM

michael.simons · January 18, 2019, 8:40am

Hi Peter.
Thanks for your question.

Currently, the Neo4j-OGM documentation points to Version 3.2 which has not been released yet. This is an error on our site.

Regarding the parameter binding: This is also a current bug in Neo4j-OGM on our site. Neo4j-OGM uses Jacksons ObjectMapper to convert parameters and that one doesn't know how do deal with JDK 8 types out of the box.

I solved this in my demo projects in the following way at the moment:

First of all: Fix the ObjectMapper. This will be done in 3.2 automatically:

github.com

michael-simons/bootiful-music/blob/38d64c272320abecc4f50c65f5060fc2303b20c4/knowledge/src/main/java/ac/simons/music/knowledge/config/Neo4jConfiguration.java#L51-L54


      
          		var objectMapper = ObjectMapperFactory.objectMapper();
          
          
		objectMapper.registerModule(new JavaTimeModule());
          		objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);

To make this work, please add GitHub - FasterXML/jackson-modules-java8: Set of support modules for Java 8 datatypes (Optionals, date/time) and features (parameter names) to your classpath.
It should be automatically available with your Spring Boot 2.1.x setup anyway.

Second step, tell Neo4j-OGM to keep away from data types it can actually pass along to embedded and Bolt instances:

github.com

michael-simons/bootiful-music/blob/38d64c272320abecc4f50c65f5060fc2303b20c4/knowledge/src/main/java/ac/simons/music/knowledge/config/Neo4jConfiguration.java#L43


      
          * @author Michael J. Simons
          */
          @Configuration
          public class Neo4jConfiguration {
          	@Bean
          	public org.neo4j.ogm.config.Configuration configuration(Neo4jProperties properties) {
          		var builder = new org.neo4j.ogm.config.Configuration.Builder();
          		builder.uri(Optional.ofNullable(properties.getUri()).orElse("bolt://localhost:7687"));
          		builder.credentials(properties.getUsername(), properties.getPassword());
          		builder.autoIndex(properties.getAutoIndex().getName());
          		builder.withCustomProperty(CONFIG_PARAMETER_CONVERSION_MODE, CONVERT_NON_NATIVE_ONLY);
          
          
		return builder.build();
          	}
          
          
	@PostConstruct
          	void configureOGMObjectMapper() {
          
          
		var objectMapper = ObjectMapperFactory.objectMapper();
          
          
		objectMapper.registerModule(new JavaTimeModule());

ParameterConversionMode is an undocumented feature for the most recent Neo4j-OGM version 3.1.6 that allows such a thing.

And last but not least, fix all the conversion mappings by providing No-Op converters that Spring Data Neo4j should keep alone:

github.com

michael-simons/bootiful-music/blob/38d64c272320abecc4f50c65f5060fc2303b20c4/knowledge/src/main/java/ac/simons/music/knowledge/support/NoOpLocalDateConversion.java

/*
 * Copyright 2018 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
 *
 *      http://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 ac.simons.music.knowledge.support;

import java.time.LocalDate;
import java.time.LocalDateTime;

This file has been truncated. show original

Use it like this:

github.com

michael-simons/bootiful-music/blob/38d64c272320abecc4f50c65f5060fc2303b20c4/knowledge/src/main/java/ac/simons/music/knowledge/support/AbstractAuditableBaseEntity.java#L41


      
          *
          * @author Michael J. Simons
          */
          @Getter
          public abstract class AbstractAuditableBaseEntity {
          	@Id
          	@GeneratedValue
          	private Long id;
          
          
	@CreatedDate
          	@Convert(NoOpLocalDateTimeConversion.class)
          	private LocalDateTime createdAt;
          
          
	@LastModifiedDate
          	@Convert(NoOpLocalDateTimeConversion.class)
          	private LocalDateTime updatedAt;
          }

I'm really sorry for that hassle, but this is the only solution.

Things will improve greatly with Spring Data Neo4j Moore (5.2) and Neo4j-OGM (3.2) which will be released with Spring Boot 2.2.
Opt-in to native types will be a simple property you'll set in your Spring Config.

Best,
Michael.

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How to use Neo4J native types with SDN and OGM

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