Neo4j Cypher query need help getting expected response

Question

Hello – I am looking for help with a cypher query that is not returning expected results for the question “Which boards is node1 pinned to depending on which user is logged in?”

Wrong result is obtained for user2. I expected that the OPTIONAL MATCH would "catch" user2 being a member of the workgroup that can access the board.

I've tried several different combinations of MATCH statements, UNION, etc.

Thanks - Jeff

I created a graph in http://console.neo4j.org/ with the following query:

CREATE (N1:node { name:"node1" })-[:PINNED_TO]->(B1:board { name:"board1" }),(N1)-[:PINNED_TO]->(B2:board { name:"board2" }),(N1)-[:PINNED_TO]->(B3:board { name:"board3" })
CREATE (U1:user { name:"user1" })-[:CREATES]->(B1),(U1)-[:CREATES]->(B2),(U3:user { name:"user3" })-[:CREATES]->(B3)
CREATE (B1)-[:CAN_VIEW]->(V1:view { name:"creator" }),(B2)-[:CAN_VIEW]->(V2:view { name:"creator AND workgroup" }),(B3)-[:CAN_VIEW]->(V3:view { name:"everyone" })
CREATE (U2:user { name:"user2" })-[:MEMBER_OF]->(WG2:workgroup { name:"B2 workgroup" })-[:CAN_ACCESS]->(B2)

I then queried the graph with the following (substituting user.name for each user):

MATCH (n:node)-[p:PINNED_TO]->(b:board)
MATCH (v:view)<-[:CAN_VIEW]-(b)<-[:CREATES]-(logged_in_user: user)
WHERE v.name = 'everyone' OR logged_in_user.name='user2'
OPTIONAL MATCH (b)<-[can_access:CAN_ACCESS]-(wg:workgroup)<-[:MEMBER_OF]-(logged_in_user)
WHERE logged_in_user.name='user2' OR can_access IS NOT NULL
RETURN DISTINCT logged_in_user.name, n.name, type(p), b.name

If “user1” is logged in, I correctly get the following:

logged_in_user.name n.name  type(p)     b.name
user1               node1   PINNED_TO   board1
user1               node1   PINNED_TO   board2
user1               node1   PINNED_TO   board3

If “user2” is logged in, I incorrectly get the following:

logged_in_user.name n.name  type(p)     b.name
user2               node1   PINNED_TO   board3

It should have returned:

logged_in_user.name n.name  type(p)     b.name
user2               node1   PINNED_TO   board2
user2               node1   PINNED_TO   board3

If “ user3” is logged in, I correctly get the following:

logged_in_user.name n.name  type(p)     b.name
user3               node1   PINNED_TO   board3

Not sure if this is the issue but you have two different cases for the workgroup node label: workgroup in the CREATE statement and workGroup in the MATCH, which will not match since labels are case sensitive. — William Lyon
Thanks for catching that. However, as @cybersam mentioned, that was not enough to fix the issue because user2 does not have an outgoing relationship to board2. I expected that the OPTIONAL MATCH would "catch" that but it is failing, I'll try more specification of nodes in that portion of the query. Any other ideas? — JeffA

cybersam cybersam · Accepted Answer · 2016-03-02T20:43:55

U1 and U3 have an outgoing CREATES relationship, but U2 (for user2) does not -- so your second MATCH will never match U2.

Also, as @WilliamLyon said, you need to use workgroup instead of workGroup in your query. But fixing that would not be sufficient to make your query work.

Neo4j Cypher query need help getting expected response

2 Answers