neo4j apoc.path.expandConfig - How to use relationshipFilter with a list of relationships

According to the documentations, the pipe char (|) acts as a or in the relationshipFilter, while the comma char (,) acts as a concatenation of relationships, creating a list of them.

see for example (look at the explanation with the black background comparing to the query itself):

and:

here, page 14: sequences:

The question is, are commas stronger than pipes? i.e., If I want several options of steps sequences, can I specify several strict lists, or do I must specify one list, each step with several options?

I wanted to achieve 4 relationship sequence options:

1.CREATE> or

2.REACT,REPLY or

3.CREATE>,RELATED or

4.REPLY>,CREATE

So I wrote a simple query:

MATCH(u:User{key:1}) CALL apoc.path.expandConfig(u, {maxLevel: 3, relationshipFilter: 'CREATE>|REACT,REPLY|CREATE>,RELATED|REPLY>,CREATE', uniqueness:"RELATIONSHIP_GLOBAL"}) YIELD path RETURN path 

Given a sample data:

MERGE (a:User{key: 1}) MERGE (b:Tags{key: 2}) MERGE (c:Post{key: 3}) MERGE (d:Comment{key: 4}) MERGE (e:Comment{key: 5}) MERGE (f:Comment{key: 6}) MERGE (g:User{key: 7}) MERGE (h:User{key: 8}) MERGE (i:Post{key: 9}) MERGE (j:Tags{key: 10}) MERGE (k:Post{key: 11}) MERGE (l:Comment{key: 12}) MERGE (a)-[:CREATE]-(b) MERGE (a)-[:CREATE]-(c) MERGE (a)-[:REACT]-(c) MERGE (a)-[:CREATE]-(d) MERGE (a)-[:REACT]-(d) MERGE (b)-[:RELATED]-(c) MERGE (d)-[:REPLY]-(c) MERGE (d)-[:REPLY]-(d) MERGE (h)-[:REACT]-(c) MERGE (g)-[:REACT]-(c) MERGE (h)-[:CREATE]-(j) MERGE (j)-[:RELATED]-(c) MERGE (g)-[:CREATE]-(i) MERGE (e)-[:REPLY]-(i) MERGE (f)-[:REPLY]-(i) MERGE (a)-[:REPLY]-(i) MERGE (h)-[:CREATE]-(k) MERGE (l)-[:REPLY]-(k) MERGE (a)-[:REACT]-(l) 

I was expecting to get an answer including (a:User{key: 1})-[:REPLY]->(i:Post{key: 9})<-[:CREATE]-(g:User{key: 7}), which corresponds with my last part of the relationshipFilter, but did not get it.

Thank you for your time

1 Answer

I believe your relationshipFilter needs to be changed.

You have written: 'CREATE>|REACT,REPLY|CREATE>,RELATED|REPLY>,CREATE' Which matches:

1. CREATE> OR REACT
2. REPLY OR CREATE
3. RELATED OR REPLY
4. CREATE (this clause is never checked because of maxLevel:3.)

It appears you intended to use the relationshipFilter: "CREATE>,REACT|REPLY,CREATE>|RELATED,REPLY>|CREATE"

Which matches

1. CREATE>
2. REACT OR REPLY
3. CREATE> OR RELATED
4. REPLY> OR CREATE