Neo4j Cypher 和嵌套的 WHERE 条件

Question

I'm trying to create the following Cypher query:

MATCH (p:Permission) 
WHERE NOT ((p)<-[:HAS|:CONTAINS*1..2]-(u:User) WHERE u.id = {userId}) AND p.minUserReputation <= {minUserReputation} 
RETURN p

I need to return all of the Permissions that are currently not assigned ( NOT ((p)<-[:HAS|:CONTAINS*1..2]-(u:User) ) to User(with u.id = {userId} ) and filtered by min reputation value ( p.minUserReputation <= {minUserReputation} )

Currently, this query fails with the following Cypher error:

Error executing Cypher; Code: Neo.ClientError.Statement.SyntaxError; Description: Variable `u` not defined

Please help to fix this query. Thanks!

Answer 1

Since WHERE <pattern> and WHERE EXISTS(<pattern>) doesn't allow additional WHERE clauses on the pattern, it's best to match on the user first, allowing you to use your WHERE clause, then include the variable for that user in your predicate:

MATCH (u:User)
WHERE u.id = {userId}
MATCH (p:Permission)
WHERE p.minUserReputation <= {minUserReputation} 
AND NOT (p)<-[:HAS|:CONTAINS*1..2]-(u) 
RETURN p