Neo4j Cypher delete query

Question

I have a following Neo4j Cypher query for Decision entity deleting:

MATCH (d:Decision) 
WHERE id(d) IN {decisionsIds} 
OPTIONAL MATCH (d)-[r]-(t) 
DELETE d, r WITH t, r 
WHERE NOT (id(t) IN {decisionsIds}) 
OPTIONAL MATCH (t)-[r2:VOTED_ON|:CREATED_BY|:VOTED_FOR]-() 
WHERE r2 <> r WITH t, r2 
WHERE none(x in labels(t) WHERE x in ['User', 'Decision']) DELETE t, r2

Previously I had a Vote entity with relationships VOTED_ON and VOTED_FOR to entities Criterion and Decision. Also, Vote has relationship CREATED_BY to User entity.

Everything worked fine.

Today, I have changed this schema. I have introduced new VoteGroup entity. Now, VoteGroup instead of Vote contains relationships VOTED_ON and VOTED_FOR to entities Criterion and Decision:

@NodeEntity
public class VoteGroup extends BaseEntity {

    private static final String VOTED_ON = "VOTED_ON";
    private final static String VOTED_FOR = "VOTED_FOR";
    private final static String CONTAINS = "CONTAINS";

    @GraphId
    private Long id;

    @RelatedTo(type = VOTED_FOR, direction = Direction.OUTGOING)
    private Decision decision;

    @RelatedTo(type = VOTED_ON, direction = Direction.OUTGOING)
    private Criterion criterion;

    @RelatedTo(type = CONTAINS, direction = Direction.OUTGOING)
    private Set<Vote> votes = new HashSet<>();

    private double avgVotesWeight;

    private long totalVotesCount;

.....

}

Vote entity now looks like:

@NodeEntity
public class Vote extends BaseEntity {

    private final static String CONTAINS = "CONTAINS";
    private final static String CREATED_BY = "CREATED_BY";

    @GraphId
    private Long id;

    @RelatedTo(type = CONTAINS, direction = Direction.INCOMING)
    private VoteGroup group;

    @RelatedTo(type = CREATED_BY, direction = Direction.OUTGOING)
    private User author;

    private double weight;

....
}

Please help me to change the mentioned Cypher query in order to delete Votes. After my schema changes it now deletes VoteGroups(it's okay) but doesn't deletes Votes. I need to delete Votes and relationships between Votes and User also.

UPDATED

The new following query working now(at least all my tests passed):

MATCH (d:Decision) 
WHERE id(d) IN {decisionsIds} 
OPTIONAL MATCH (d)-[r]-(t) 
DELETE d, r 
WITH t, r 
WHERE NOT (id(t) IN {decisionsIds}) 
OPTIONAL MATCH (t)-[r2:VOTED_ON|:CREATED_BY|:VOTED_FOR]-()-[r3:CONTAINS]-(t2) 
WHERE r2 <> r 
WITH t, r2, t2, r3 
WHERE none(x in labels(t) 
WHERE x in ['User', 'Decision']) 
DELETE t, r2, t2, r3

but I'm still not sure that this query is 100% correct... Anyway, I'll add a bunch of tests in order to check everything.

Could you please validate this query also? Especially I'm not sure that deleted all the relationships and did not leave the garbage in the database.

Michael Hunger Michael Hunger · Accepted Answer · 2015-08-10T12:30:11

Looks pretty complicated.

Can't you just specify the path and delete the whole path?

MATCH (d:Decision) WHERE id(d) IN {decisionsIds} 
OPTIONAL MATCH path = (d)-[r1:VOTED_ON|:CREATED_BY|:VOTED_FOR]->(t)<-[r2:VOTED_ON|:CREATED_BY|:VOTED_FOR]-()
DELETE path

// or 
DELETE d,t,r1,r2

Neo4j Cypher delete query

1 Answers