How to list relationships by type in a Cypher @Query annotated method?

[hsherlock]

Hi,

Is it possible to list related items of an item filtered by relationship type like below?

@NodeEntity
public class POJO
{

....

private Iterable<POJO> relatedByType;

@Query("START n1=node({self}) MATCH n1-[rel:{type}]->n2 RETURN n2")
public Iterable<POJO> getRelatedByType(@Param("type") String type)
{
return relatedByType;
}

}

I tried it, but it always returns empty result.

Thank you in advance for any help!

[lassewesth]

hsherlock,

Can you create a small example in http://console.neo4j.org, run the query, and share the results?

Thanks,

Lasse

[hsherlock]

Hi Lasse,

Unfortunately I don't think it could be demonstrated in the Neo4j console because I didn't found any way to pass query-external parameters in format {...}. Actually, the query is ok, because when I execute it with exact type name instead of [:{type}] it returns correct results.

I tested again and the following method always returns empty (Iterable) result.

@Query("START n1=node({self}) MATCH n1-[rel:{type}]->n2 RETURN n2")
public Iterable<POJO> getRelatedByType(@Param("type") String type)
{
return relatedByType;
}

p.s. In the meantime I think I've found another related problem http://forum.springsource.org/showth...e-like-type-gt

[lassewesth]

hsherlock,

Parameterised relationship types are not supported: http://docs.neo4j.org/chunked/milest...arameters.html

Regards,

Lasse

[hsherlock]

Ok, now I see - it is not allowed to insert parameters like MATCH ....[rel:{NOT_ALLOWED}]...

Tried to slightly modify the query according the example from "Good Relationships" book
.... WHERE rel.type='some_type'...
Failed both in cypher query invoked from Java code and in http://console.neo4j.org/
It looks that .type property of a Relationship cannot be accessed this way.

While hacking with http://console.neo4j.org/ noted "type(rel)" and the query finally works both from java and in console when
.... WHERE type(rel)='someType'...
.... WHERE type(rel)={relType} ...

Now returning back to the @Query annotated method which now became:
@Query(value="START n=node({self}) MATCH n-[rel]->relN WHERE type(rel)={relType} RETURN relN")
public Iterable<POJO> getRelationshipsByType(@Param("relType") String type)
{
return relationshipsByType;
}
Again - empty result!

[lassewesth]

hsherlock,

I am as mystified as you are. One thing to try though quickly, I think you might have to name the query parameter the same as the method parameter - i.e. ignoring the @Param bit, if the method parameter name is 'foo' you can refer to {foo} in the query.

Let me know the outcome.

Lasse

[hsherlock]

Hi Lasse,

Tried as you suggested and renamed the method argument as below
public Iterable<POJO> getRelationshipsByType(@Param("relType") String relType)
No success here - same result - empty result returned.

In the meantime I've noted that the query is not executed at all and no exception is produced even if I put totally invalid query there and it looks as the core problem now. As it does not look like a paramer handling issue anymore I posted this as another thread http://forum.springsource.org/showth...s-not-invoked-!