CODEWITHSUNDEEP
neo4j
Hammerbot
Hammerbot

Reputation: 16364

How to avoid specific paths in allShortestPath function?

enter image description here

The graph is supposed to represent a system similar to github, with commits (commit1, commit2, commit3 and commit4), documents (d1, d2) and changes on those documents (green nodes).

I am trying to use CYPHER to get all the documents values at a specific commit. In other words, I am trying to find the shortest path between the specific commit and each of the documents on my graph, but avoiding some paths.

Imagine if I am on commit4, d1 should be equal to foo2 and d2 should be equal to spain. This could be solved with the following CYPHER query:

MATCH (c:Commit {id: 'commit4'})-[:FOLLOWS|CHANGED*]->(:Value)<-[:EQUALS]-(d:Document), p = allShortestPaths((c)-[*]-(d))
RETURN p

This would give the following response:

enter image description here

Now, imagine that I want to be get the values on commit3. The request should not return any changes from the commit4. However, if I use the allShortestPaths function the way I do, it will go through commit4 since it is actually the shortest path to d1 and return the exact same response than if my starting node was commit4.

MATCH (c:Commit {id: 'commit3'})-[:FOLLOWS|CHANGED*]->(:Value)<-[:EQUALS]-(d:Document), p = allShortestPaths((c)-[*]-(d))
RETURN p

How could I avoid the allShortestPath function to go through a [:FOLLOWS]->(c) relationship and solve my problem?

Upvotes: 1

Views: 74

Answers (1)

NonameCurious
NonameCurious

Reputation: 606

From what you explained, I understand that you don't want to traverse the FOLLOWS edge in the opposite direction of the edge. To do so you can use cypher projection in algo.shortestPath:

MATCH (start:Commit {name:'commit4'}) 
MATCH (end:Document)
CALL algo.shortestPath.stream(start, end, null,{
nodeQuery:'MATCH (n) RETURN id(n) AS id',
relationshipQuery:'MATCH (n)-[r:FOLLOWS|CHANGED]->(p) RETURN id(n) AS source, id(p) AS target UNION MATCH (n)-[r:EQUALS]-(p) RETURN id(n) AS source, id(p) AS target',
graph:'cypher'})
YIELD nodeId, cost
WITH end as document, algo.asNode(nodeId) AS value WHERE "Value" in labels(value)
return document, value

Replace "commit4" with any other commit name.

Upvotes: 1

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