Spring Neo4j: Erreur dans "neo4jTemplate.save()"

Question

J'utilise spring-neo4j-data dans mon projet java. Je reçois l'erreur suivante lors de l'enregistrement d'une entité:

Versions:

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

    <dependency> 
     <groupId>org.neo4j</groupId> 
     <artifactId>neo4j-lucene-index</artifactId> 
     <version>2.0.1</version> 
    </dependency> 
    <dependency> 
     <groupId>org.neo4j</groupId> 
     <artifactId>neo4j-kernel</artifactId> 
     <version>2.0.1</version> 
    </dependency> 

code:

Entité Utilisateur:

@NodeEntity 
public class User { 

    @GraphId 
    Long id; 

    @Indexed(unique=true) 
    private String uid; 

    private String name; 
    private UserDetails userDetails; 

    @RelatedToVia(type = "FRIEND", direction = Direction.BOTH) 
    private Set<Friendship> friendships; 

    @RelatedToVia(type = "FOLLOWS", direction = Direction.OUTGOING) 
    private Set<Follows> follows; 

    public User() { 
    } 

    public User(String uid) { 
     this.uid = uid; 
    } 

    public Friendship friendOf(Neo4jOperations template, User friend, FriendshipType friendshipType) { 
     final Friendship friendship = template.createRelationshipBetween(this, friend, Friendship.class, "FRIEND", false); 
     friendship.addFriendshipType(friendshipType); 
     return template.save(friendship); 
    } 

    public Follows follows(Neo4jOperations template, User following, FollowerType followerType) { 
     final Follows follows = template.createRelationshipBetween(this, following, Follows.class, "FOLLOWS", false); 
     follows.addFollowerType(followerType); 
     return template.save(follows); 
    } 

    // Getters and Setters start 
    public Long getId() { 
     return id; 
    } 

    public String getUid() { 
     return uid; 
    } 

    public void setName(String name) { 
     this.name = name; 
    } 

    public String getName() { 
     return name; 
    } 

    public void setUserDetails(UserDetails userDetails) { 
     this.userDetails = userDetails; 
    } 

    public UserDetails getUserDetails() { 
     return userDetails; 
    } 

    public Set<Friendship> getFriendships() { 
     return friendships; 
    } 

    // Getters and Setters end 

    @Override 
    public boolean equals(Object obj) { 
     if (this == obj) 
      return true; 

     if (obj == null || obj.getClass() != this.getClass()) 
      return false; 

     User user = (User) obj; 
     return this.getUid().equals(user.getUid()); 
    } 

    @Override 
    public int hashCode() { 
     final int prime = 31; 
     int result = 3; 
     result = prime * result + this.getUid().hashCode(); 
     return result; 
    } 

} 

Amitié Pojo:

@RelationshipEntity(type = "FRIEND") 
public class Friendship { 

    @GraphId 
    private Long id; 

    @StartNode 
    private User u1; 

    @StartNode 
    private User u2; 

    private Set<FriendshipType> friendshipTypes; 

// public Friends(User u1, User u2, FriendshipType... friendshipTypes) { 
//  this.u1 = u1; 
//  this.u2 = u2; 
//  this.friendshipTypes = new HashSet<>(); 
//  for (FriendshipType type : friendshipTypes) 
//   this.friendshipTypes.add(type); 
// } 

    public void addFriendshipType(FriendshipType friendshipType) { 
     if (friendshipTypes == null) 
      friendshipTypes = new HashSet<>(); 
     friendshipTypes.add(friendshipType); 
    } 

} 

Test:

public class Test { 
    private void run(Neo4jTemplate template) { 
     User john = new User("john_uid"); 
     template.save(john); 
    } 
} 

Exception:

Exception in thread "main" java.lang.NullPointerException 
at org.springframework.data.neo4j.fieldaccess.RelationshipEntities.<init>(RelationshipEntities.java:46) 
at org.springframework.data.neo4j.fieldaccess.RelatedToViaCollectionFieldAccessorFactory$RelatedToViaCollectionFieldAccessor.<init>(RelatedToViaCollectionFieldAccessorFactory.java:74) 
at org.springframework.data.neo4j.fieldaccess.RelatedToViaCollectionFieldAccessorFactory.forField(RelatedToViaCollectionFieldAccessorFactory.java:56) 
at org.springframework.data.neo4j.fieldaccess.FieldAccessorFactoryProviders$FieldAccessorFactoryProvider.accessor(FieldAccessorFactoryProviders.java:46) 
at org.springframework.data.neo4j.fieldaccess.FieldAccessorFactoryProviders.getFieldAccessors(FieldAccessorFactoryProviders.java:74) 
at org.springframework.data.neo4j.fieldaccess.DefaultEntityState.<init>(DefaultEntityState.java:52) 
at org.springframework.data.neo4j.support.node.NodeEntityState.<init>(NodeEntityState.java:38) 
at org.springframework.data.neo4j.support.node.NodeEntityStateFactory.getEntityState(NodeEntityStateFactory.java:48) 
at org.springframework.data.neo4j.support.mapping.SourceStateTransmitter.copyPropertiesTo(SourceStateTransmitter.java:98) 
at org.springframework.data.neo4j.support.mapping.Neo4jEntityConverterImpl.write(Neo4jEntityConverterImpl.java:167) 
at org.springframework.data.neo4j.support.mapping.Neo4jEntityPersister$CachedConverter.write(Neo4jEntityPersister.java:179) 
at org.springframework.data.neo4j.support.mapping.Neo4jEntityPersister.persist(Neo4jEntityPersister.java:243) 
at org.springframework.data.neo4j.support.mapping.Neo4jEntityPersister.persist(Neo4jEntityPersister.java:231) 
at org.springframework.data.neo4j.support.Neo4jTemplate.save(Neo4jTemplate.java:311) 
at org.springframework.data.neo4j.support.Neo4jTemplate.save(Neo4jTemplate.java:305) 
at org.springframework.data.neo4j.repository.AbstractGraphRepository.save(AbstractGraphRepository.java:111) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:606) 
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:358) 
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:343) 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) 
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:96) 
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:260) 
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:94) 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) 
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:155) 
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172) 
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204) 
at com.sun.proxy.$Proxy35.save(Unknown Source) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:606) 
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317) 
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:198) 
at com.sun.proxy.$Proxy47.save(Unknown Source) 
at com.music.Test.run(Test.java:43) 
at com.music.Test.main(Test.java:37) 

Answer 1

Il semble aussi être le code manquant, car il se plaint de relations-entités.

Peut-être que vous pouvez partager un projet sur github ou qui présente le problème?

Une partie de votre code était également faux, je l'ai corrigé ci-dessous. Vous pouvez également utiliser repo.save() pour créer une entité de manière unique.

@NodeEntity 
public class User { 

    @GraphId 
    Long id; 

    @Indexed(unique=true) 
    private String uid; 

    public User(String uid) { 
     this.uid = uid; 
    } 
} 

public interface UserRepository extends GraphRepository<User> { 

    public User getUserByUid(String userId); 

    @Query(
     "MERGE (user:User {userId:{0}} RETURN user" 
    ) 
    public User createUserIfNotExists(String userId); 
} 

public class Test { 
    private void run(UserRepository userRepository) { 
     User john = new User("john_uid"); 
     userRepository.save(john); 
    } 
} 

En ce qui concerne votre relation entité, vous avez une copie & faute de frappe de la pâte, vous avez @StartNode deux fois.

@StartNode 
private User u1; 

@StartNode 
private User u2;