CODEWITHSUNDEEP
neo4jcyphernodesrelationships
Goofball
Goofball

Reputation: 755

Neo4j - extract property data of nodes in a path and the relationship pointing to those nodes

I'd like to write a compact query for the following data structure.

Node n1 up to node 1000 are connected via the relation 'rel1' Each node n has the property n.name Another node (only one exists) Q has relation 'rel2' to each node n1 with a relationship property q.value

(n1)-[rel1]->(n2)-[rel1]->(n3)--[rel1]-......->(n1000)
(Q)-[rel2]->(n1), (Q)-[rel2]->(n2),(Q)-[rel2]->(n3)....... (Q)-[rel2]->(n1000)

I want to extract this data: a list of the 1000 names (n.name) in order of appearance and a list of the 1000 q.values that point to each node n

I get as far as retrieving all the names nodes n by using a collection function

match p=(n)-[r:rel1*..]->(m) where  n.nodeNumber = 1 and m.nodeNumber=1000 RETURN extract(n IN nodes(p)| n.name) AS name 
ORDER BY length(p) DESC
LIMIT 1

Can I easily extract all the q.values that point to these nodes as well? Ideally in one statement.

Upvotes: 1

Views: 3589

Answers (2)

Goofball
Goofball

Reputation: 755

Just to correct the previous elegant command. a ) was missing and you need to specify the length of the path to search. By default it is only 15 or so. I added 1100 in the command as 1000 nodes were given. I also changed n to nlist as Neo4j complained about n being declared twice.

The updated command is here:

match p=shortestPath((n:Label)-[r:rel1*..1500]->(m:Label))
where  n.nodeNumber = 1 and m.nodeNumber=1000 
UNWIND nodes(p) as nlist
MATCH (nlist)<-[:rel2]-(q:Q)
RETURN nlist.name, q.value;

Upvotes: 1

Michael Hunger
Michael Hunger

Reputation: 41706

Make sure to use labels + indexes to find your start and end-node quickly. If you use shortest-path it only finds one path.

match p=shortestPath((n:Label)-[r:rel1*..]->(m:Label) 
where  n.nodeNumber = 1 and m.nodeNumber=1000 
RETURN extract(n IN nodes(p) | {name: n.name, value: head([p in (n)<-[:rel2]-() | last(nodes(p)).value]) ) AS data
ORDER BY length(p) DESC
LIMIT 1

more elegant:

match p=shortestPath((n:Label)-[r:rel1*..]->(m:Label) 
where  n.nodeNumber = 1 and m.nodeNumber=1000 
UNWIND nodes(p) as n
MATCH (n)<-[:rel2]-(q:Q)
RETURN n.name, q.value;

Upvotes: 2

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