Neo4j cypher查询已知路径

Question

I have a query that I'm not sure how to implement or if it's efficient to do in cypher . Anyway, here's what I'm trying to do.

I have basically this graph:

I want to get all the nodes / relationships from 1 to 3 ( note : the empty node can be any number of nodes). I also want all the, if any , incoming edges from the last two nodes and only the last two nodes that are not in the original path. In this case the edges that are in red should also be added to result.

I already know the path that I want. So in this example I would have been given node ids 1, ..., 2, 3 and I think I know how to get the path of the first part.

MATCH (n)-->() WHERE n.nid IN ['1', '...', '2', '3'] RETURN n

I just can't figure out how to get the red edges for the last two nodes in the path. Also, I'm not given node ids 4 and 5. We can assume the edges connecting 1, ..., 2, 3 all have the same label and all the other edges have a different label .

I think I need to use merge but can't figure out how to do it yet.

Or if someone know's how to do this in gremlin, I'm all ears.

Answer 1

Does this work for you?

MATCH ({nid: '1'})-[:t*]->(n2 {nid: '2'})-[:t]->(n3 {nid: '3'})
OPTIONAL MATCH ()-[t42]->(n2)
  WHERE (TYPE(t42) <> 't')
OPTIONAL MATCH ()-[t53]->(n3)
  WHERE (TYPE(t53) <> 't')
RETURN COLLECT(t42) AS c42, COLLECT(t53) AS c53;

I give all the relationships on the left path (in your diagram) the type "t". (The term label is used for nodes, not relationships.). You said we can assume that the other relationships do not have that type, so this query takes advantage of that fact to filter out type "t" relationships from the result.

This query also makes the 4-2 and 5-3 relationships optional.