Question

I’m new to Neo4J and I have, probably an easy question.

There’re NodeEntitys in my application, a property (name) is annotated with @Indexed(unique = true) to achieve the uniqueness like I do in JPA with @Column(unique = true).

My problem is, that when I persist an entity with a name that already exists in my graph, it works fine anyway.
But I expected some kind of exception here…?!
Here’ s an overview over basic my code:

@NodeEntity
public abstract class BaseEntity implements Identifiable
{
    @GraphId
    private Long entityId;
    ...
}

public class Role extends BaseEntity
{
    @Indexed(unique = true)
    private String name;
    ...
}

public interface RoleRepository extends GraphRepository<Role>
{
    Role findByName(String name);
}

@Service
public class RoleServiceImpl extends BaseEntityServiceImpl<Role> implements 
{
    private RoleRepository repository;

    @Override
    @Transactional
    public T save(final T entity) {
    return getRepository().save(entity);
    }
}

And this is my test:

@Test
public void testNameUniqueIndex() {
    final List<Role> roles = Lists.newLinkedList(service.findAll());
    final String existingName = roles.get(0).getName();
    Role newRole = new Role.Builder(existingName).build();
    newRole = service.save(newRole);
}

That’s the point where I expect something to go wrong!
How can I ensure the uniqueness of a property, without checking it for myself??

P.S.: I’m using neo4j 1.8.M07, spring-data-neo4j 2.1.0.BUILD-SNAPSHOT and Spring 3.1.2.RELEASE.

Answer 1

I walked into the same trap… as long as you create new entities, you will not see the exception – the last save()-action wins the battle.

Unfortunately, the DataIntegrityViolationException will be raised only in case of update an existing entity!

A detailed description of that behaviour can be found here:
http://static.springsource.org/spring-data/data-graph/snapshot-site/reference/html/#d5e1035