NullPointerException in ExecutionEngine on startup about java-rest-binding

[sparmboy]

Upon further investigation, it looks as though this only occurs when enabling Spring Data Neo4j repositories. I have created a simple repo to reproduce this but unfortunately im unable to push the repo to github as im behind a corporate firewall. Appologies but I will post each file here:

App.java

package com.mypackage;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.ComponentScan;

@ComponentScan("com.mypackage")
@EnableAutoConfiguration
public class App
{
    public static void main(String args[])
    {
    SpringApplication.run(App.class, args);     
    } 

}

CustomNeo4jConfiguration.java

package com.mypackage;

import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.rest.graphdb.RestGraphDatabase;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.DependsOn;
import org.springframework.data.neo4j.config.EnableNeo4jRepositories;
import org.springframework.data.neo4j.config.Neo4jConfiguration;
import org.springframework.data.neo4j.core.GraphDatabase;
import org.springframework.data.neo4j.support.DelegatingGraphDatabase;
import org.springframework.data.neo4j.support.Neo4jTemplate;

@Configuration
//@EnableNeo4jRepositories("com.mypackage")
public class CustomNeo4jConfiguration
{
    GraphDatabaseService localDatabaseService;

    /*@Bean
    @DependsOn("graphDatabase")
    public Neo4jTemplate neo4jTemplate()
    {
        return new Neo4jTemplate(graphDatabase());
    }*/

    @Bean
    @Autowired
    @DependsOn("graphDatabaseService")
    public GraphDatabase graphDatabase()
    {
        if (localDatabaseService instanceof GraphDatabase) return (GraphDatabase) localDatabaseService;
        return new DelegatingGraphDatabase(localDatabaseService);
    }


    @Bean
    public GraphDatabaseService graphDatabaseService()
    {
        if (this.localDatabaseService == null)
        {
            String remoteDBURL = "http://localhost:7474/db/data";
            System.setProperty("org.neo4j.rest.read_timeout","30");
            System.setProperty("org.neo4j.rest.connect_timeout","30");
            System.setProperty("org.neo4j.rest.driver","neo4j-rest-graphdb/2.0.1");
            System.setProperty("org.neo4j.rest.stream","true");
            System.setProperty("org.neo4j.rest.batch_transaction","false");
            System.setProperty("org.neo4j.rest.logging_filter","false");

            this.localDatabaseService = new RestGraphDatabase(remoteDBURL);

        }

        return this.localDatabaseService;
    }

}

MyNodeEntity.java

package com.mypackage;

import org.springframework.data.neo4j.annotation.GraphId;
import org.springframework.data.neo4j.annotation.NodeEntity;


@NodeEntity
public class MyNodeEntity
{
    @GraphId
    Long id;
}

MyNodeRepository.java

package com.mypackage;

import org.springframework.data.neo4j.repository.GraphRepository;


public interface MyNodeRepository extends GraphRepository<MyNodeEntity>
{

}

MyService.java

package com.mypackage;

import org.neo4j.graphdb.GraphDatabaseService;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class MyService implements InitializingBean      
{
    @Autowired
    GraphDatabaseService gds;

    public void afterPropertiesSet() throws Exception
    {
        System.out.println("Success = " + gds.getAllNodes().iterator().next() );
    }


}

pom.xml

<?xml version="1.0"?>
<project
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
    xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>0.5.0.M6</version>
        <!-- <version>1.0.0.RC1</version> -->
    </parent>

    <groupId>com.mypackage</groupId>
    <artifactId>neo4j-remote</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>neo4j-remote</name>
    <url>http://maven.apache.org</url>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <build>
        <plugins>

            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>



        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-neo4j</artifactId>
            <version>3.0.0.RC1</version>
        </dependency>


        <dependency>
            <groupId>org.neo4j</groupId>
            <artifactId>neo4j-rest-graphdb</artifactId>
            <version>2.0.0</version>
        </dependency>


    </dependencies>




    <repositories>
        <repository>
            <id>neo4j-release-repository</id>
            <name>Neo4j Maven 2 release repository</name>
            <url>http://m2.neo4j.org/content/repositories/releases/</url>
            <releases>
                <enabled>true</enabled>
            </releases>
            <snapshots>
                <enabled>false</enabled>
            </snapshots>
        </repository>
        <repository>
            <id>neo4j-snapshot-repository</id>
            <name>Neo4j Maven 2 snapshot repository</name>
            <url>http://m2.neo4j.org/snapshots</url>
            <snapshots>
                <enabled>true</enabled>
            </snapshots>
            <releases>
                <enabled>false</enabled>
            </releases>
        </repository>
        <repository>
            <id>Sun</id>
            <url>http://download.java.net/maven/2</url>
        </repository>

    </repositories>


</project>

To run this:

• Startup a local instance of Neo4j server on localhost:7474 (ensure you have a least one node in it)

• Build the app by running

  mvn clean package

• Run the app with:

  java -jar target\neo4j-remote-1.0-SNAPSHOT.jar

• You should see the app connect and dump out the line:

  Success = http://localhost:7474/db/data/node/0

• Now in the CustomNeo4jConfiguration uncomment the following two sections:

  @EnableNeo4jRepositories("com.mypackage")

and
@Bean @DependsOn("graphDatabase") public Neo4jTemplate neo4jTemplate() { return new Neo4jTemplate(graphDatabase()); }

• Now re-build and run again and you should see the NullPointerException thrown

[AndrewWestberg]

Is there a work-around for this issue? Or is using a RestGraphDatabase and spring-boot just plain broken?

[jexp]

Andrew it is not broken at all. Just wrapping a RestGraphDatabase in a DelegatingDatabase is nothing anyone would ever do. Just use SpringRestGraphDatabase(url)

See this example: https://github.com/neo4j-contrib/developer-resources/tree/gh-pages/language-guides/java/spring-data-neo4j

[AndrewWestberg]

@jexp Thanks much. Very helpful.