Razor Razor - 1 year ago 90
Java Question

neo4j null pointer exception while saving via @Repository

The sample project i'm working with can be found attached here -
Spring Jira

This is my configuration

@EnableNeo4jRepositories(basePackages = "com.graph.repository")
public class DBConfig extends Neo4jConfiguration{
private String neo4jDatabaseLocation;

public SessionFactory getSessionFactory() {
return new SessionFactory(getConfiguration(), "com.graph.entity");

public Configuration getConfiguration() {
Configuration configuration = new Configuration();
return configuration;

public Session getSession() throws Exception {
return getSessionFactory().openSession();

Abstract Entity

public abstract class Entity {
private Long id;

public Long getId() {
return id;

public boolean equals(Object o) {
if (this == o) return true;
if (o == null || id == null || getClass() != o.getClass()) return false;

Entity entity = (Entity) o;

if (!id.equals(entity.id)) return false;

return true;

public int hashCode() {
return (id == null) ? -1 : id.hashCode();

This is my Entity

@NodeEntity(label = "Patient")
public class Patient extends Entity {
private String patientId;
private String patientName;
private String otherPatientId;
private String sex;
private String dateOfBirth;
private String patientIdIssuer;
@Relationship(type = "STUDY", direction = Relationship.UNDIRECTED)
private Set<Study> studies;

Getters and Setters...

Study has nested entity/relationship and that has another nested entity/relationship. 1:N relationship

This is my repository

public interface PatientRepository extends GraphRepository<Patient> {

And this is the calling method

public class Test() {
private PatientRepository patientRepository;

public void test() {
Patient patient = new Patient();
// set fields
patientRepository.save(patient); -> This is where I get NPE

Stack Trace :

Caused by: java.lang.NullPointerException: null
at org.neo4j.ogm.drivers.embedded.driver.EmbeddedDriver.nativeTransaction(EmbeddedDriver.java:180) ~[neo4j-ogm-embedded-driver-2.0.4.jar:na]
at org.neo4j.ogm.drivers.embedded.driver.EmbeddedDriver.newTransaction(EmbeddedDriver.java:148) ~[neo4j-ogm-embedded-driver-2.0.4.jar:na]
at org.neo4j.ogm.session.transaction.DefaultTransactionManager.openTransaction(DefaultTransactionManager.java:57) ~[neo4j-ogm-core-2.0.4.jar:na]
at org.neo4j.ogm.session.delegates.TransactionsDelegate.beginTransaction(TransactionsDelegate.java:37) ~[neo4j-ogm-core-2.0.4.jar:na]
at org.neo4j.ogm.session.Neo4jSession.beginTransaction(Neo4jSession.java:441) ~[neo4j-ogm-core-2.0.4.jar:na]
at org.neo4j.ogm.session.request.RequestExecutor.executeSave(RequestExecutor.java:84) ~[neo4j-ogm-core-2.0.4.jar:na]
at org.neo4j.ogm.session.delegates.SaveDelegate.save(SaveDelegate.java:75) ~[neo4j-ogm-core-2.0.4.jar:na]
at org.neo4j.ogm.session.delegates.SaveDelegate.save(SaveDelegate.java:44) ~[neo4j-ogm-core-2.0.4.jar:na]
at org.neo4j.ogm.session.Neo4jSession.save(Neo4jSession.java:425) ~[neo4j-ogm-core-2.0.4.jar:na]

Can someone please tell me what I'm doing wrong??

Note : I had this working earlier with sdn.3.x with GraphDatabaseService

Answer Source

Looks like the only thing missing is the @Configuration annotation on your Neo4jConfiguration class:

@EnableNeo4jRepositories(basePackages = "com.seyfert.matrix.graph.repository")
public class DBConfig extends Neo4jConfiguration{
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