Return all nodes and relations among nodes in path

Question

First time asking on SO and a newby of cypher and neo4j.

I need to get all the nodes, and all their relationships, that compose the lineage of a particular node; to display them in a directed graph I need a list of nodes and a list of the relationships (links). This is my dummy set of nodes, and this is what I want to get (nodes plus links): result

This is what I came up after hours of research and attempts:

MATCH lineage = (n:Sample {name:"P"})-[:CHILD_OF*]->(parent:Sample)
MATCH (parent)-[r_out]->(child)-[r_in]->(parent)
WHERE parent IN nodes(lineage) OR child IN nodes(lineage) 
RETURN
collect(DISTINCT parent) AS nodes,
collect({ source: parent.name, rel: type(r_out), target: child.name }) AS links_out,
collect({ source: child.name, rel: type(r_in), target: parent.name }) AS links_in;

(I created two different list of relationships so i can distinguish the source and target.)

However this does not return n in the list of nodes and actually multiplicates the links, as I guess returns all the possible paths between n and all the other nodes.

I could not figure out a solution and I am also convinced it should be a much more elegant query...

Any help? Thanks

Stefano Stefano · Accepted Answer · 2017-01-21T08:20:47

This is what I was looking for!

MATCH lineage = (child:Sample {name:"P"})-[:CHILD_OF*]->(parent:Sample)
MATCH (n:Sample)-[r_out]->(m:Sample)-[r_in]->(n:Sample)
   WHERE n IN nodes(lineage) AND m IN nodes(lineage)
RETURN
   child + collect(DISTINCT parent) AS nodes,
   collect(DISTINCT {source: n.name, rel: type(r_out), target: m.name}) +
   collect(DISTINCT {source: m.name, rel: type(r_in), target: n.name}) AS links

The plus sign merges the results in a single array, and so now I have in a single query my two arrays of nodes and links! :)

Return all nodes and relations among nodes in path

2 Answers