Neo4j Cypher RETURN 与模式理解中的 OPTIONAL MATCH

Question

I use the following Neo4j Cypher RETURN statement with pattern comprehensions:

[ (c1)<-[vg1:HAS_VOTE_ON]-(childD) | {criterion: c1, relationship: vg1} ] AS weightedCriteria

which works fine.

I'd like to extend it a little bit to return more information, to something like this:

[ (c1)<-[vg1:HAS_VOTE_ON]-(childD) WITH c1, vg1 
    OPTIONAL MATCH (c1)-[rc1t:CONTAINS]->(c1t:Translation {deleted: false}) 
    WHERE ($iso6391 IS NOT null AND c1t.iso6391 = $iso6391) | {criterion: c1, relationship: vg1, translation: c1t} ] AS weightedCriteria

but such a query fails with org.neo4j.ogm.exception.CypherException: Cypher execution failed with code 'Neo.ClientError.Statement.SyntaxError on WITH

Is it possible to implement with pattern comprehensions?

Answer 1

Since pattern comprehension is a form of a subquery, you can use complete subquery syntax to achieve what you want.

Here, I am assuming you started with c1

CALL {
  WITH c1
  MATCH (c1)<-[vg1:HAS_VOTE_ON]-(childD) 
  WITH c1, vg1 
  OPTIONAL MATCH (c1)-[rc1t:CONTAINS]->(c1t:Translation {deleted: false}) 
  WHERE ($iso6391 IS NOT null AND c1t.iso6391 = $iso6391)
  RETURN {criterion: c1, relationship: vg1, translation: c1t}
}

Answer 2

Pattern comprehension is like a for loop but simplified and compact form. So you cannot put another MATCH inside of it. Try below query and let us know if it works or not.

MATCH (c1)<-[vg1:HAS_VOTE_ON]-(childD)  
OPTIONAL MATCH (c1)-[rc1t:CONTAINS]->(c1t:Translation {deleted: false}) 
WHERE $iso6391 IS NOT null AND c1t.iso6391 = $iso6391
RETURN collect({criterion: c1, relationship: vg1, translation: c1t}) AS weightedCriteria