Hi,
I'm trying to override the "boolean exists(Long)" function in my
CrudRepositories interfaces, and I think I have found an inconsistency in
Cypher about the "return" clause.
The method I want to add to "CommunityRepository" is :
@Override
@Query(value = "match (n:Community) where id(n)={id} return count(n) >
0")
public boolean exists(@Param("id") Long id);
What happens is this :
- if the node whose "id" is given carries the label ":Community", then this
request will return a boolean "true", which is the expected behaviour.
- if the node doesn't carry the ":Community" label (for example it carries
":Institution"), then the request will return "0 row" which is not a
boolean value.
So the bug is that "return count(n) > 0" is ignored when there is no node
returned.
Some help would be really appreciated as I don't know how to solve my
original issue involving the "exists" function.
Thanks,
Grégoire
Le mercredi 5 mars 2014 16:27:48 UTC+1, Grégoire Colbert a écrit :
>
> Hi,
>
> I have an abstract class "OrganisationNode" containing a "@GraphId id"
> field.
>
> I have several concrete classes extending OrganisationNode, for example
> "InstitutionNode" or "CommunityNode". None of them have a @GraphId field.
> If I put another "@GraphId id" field on InstitutionNode, I get the
> following error "Attempt to add id property private java.lang.Long
> eu.ueb.acem.domain.beans.rouge.neo4j.OrganisationNode.id but already have
> property private java.lang.Long
> eu.ueb.acem.domain.beans.rouge.neo4j.InstitutionNode.id registered as id.
> Check your mapping configuration!"
>
> However, this seems ok at first, because each of my DAOs (e.g.
> InstitutionDAO, CommunityDAO, etc) contain a CrudRepository instance
> specific to a given concrete class. It can create nodes and they have the
> good labels, e.g. if I call InstitutionRepository.create("my new
> institution"), the resulting node will have the labels : "Organisation",
> "Institution" and "_Institution". That's exactly what I want.
>
> The problem is that CrudRepository#exists returns true, even if I mix the
> concrete classes. For example, if I call InstitutionRepository#exists(id of
> a CommunityNode), it returns true! The same thing happens with
> CommunityRepository#exists(id of an InstitutionNode).
>
> It seems that the @GraphId concerns the OrganisationNode and that the
> "exists" method doesn't care about the type associated with the
> CrudRepository. I would find logical the following results :
> - InstitutionRepository#exists(id of a InstitutionNode) to return true
> - InstitutionRepository#exists(id of a CommunityNode) to return false
>
> Is that a bug? Or is that how it is supposed to work, and should I
> overwrite the "exists" method?
>
> Thanks!
>
> Grégoire
>
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