CODEWITHSUNDEEP
neo4jcypher
Barnacle_Ed
Barnacle_Ed

Reputation: 80

Returning on-the-fly relationship in graph form in Neo4j

I'm pretty new to Neo4j and graph DBs in general, and have been playing around with it for the last few days. I've now hit something I'm stumped on: I'm trying to create a "temporary" relationship between two disjoint nodes just for the sake of a RETURN, then not store this relationship within the DB afterwards.

The dataset I'm using is a graph of Movie and Person nodes provided in one of the basic Neo4j built-in tutorials. My query is currently as follows:

MATCH (p1:Person)-[r1:ACTED_IN]-(m1:Movie)-[r2:ACTED_IN]-(p2:Person)
WHERE p1.name="Kevin Bacon"
RETURN {start:p1,rel:"COSTAR",end:p2}

What I'd ultimately like to see is a central "Kevin Bacon" node with COSTAR relationships to a series of Person nodes around it, without any Movie nodes or ACTED_IN relationships being displayed. The query above does show the COSTAR relationship in the returned rows, but it does not appear on the graph itself; I've attached a few screenshots of what I'm seeing.

The only other idea I have is to use the MERGE keyword to create a COSTAR relationship, but (as I understand it) this actually stores the relationship in the DB which is what I'm trying to avoid.

Any suggestions would be greatly appreciated.

"Graph result, note that COSTAR is *not* present

"Rows" result, note that COSTAR is present

Upvotes: 1

Views: 678

Answers (3)

fadesibert
fadesibert

Reputation: 1

The best way to achieve this (now... 6 years later) is with the gds.graph.create.* functions (assuming you load GDS) https://neo4j.com/docs/graph-data-science/current/graph-create/

With a graph as simple as this, gds.graph.create(...) would be enough (creating COSTAR for all co-starrings)

Or, if you wanted to do some constraining, gds.graph.create.cypher(...)

The in-memory graph projection feels like what you wanted to achieve - it persists only as long as the DBMS is active, or until you call gds.graph.drop(...)

Upvotes: 0

cybersam
cybersam

Reputation: 66967

The neo4j Browser only visualizes nodes and relationships that actually exist in the DB. So, there is no way to do what you want without actually creating the COSTAR relationships, visualizing the result in the Browser, and then deleting all the COSTAR relationships.

As a workaround you could simply display the nodes of all of Kevin Bacon's costars, like this:

MATCH (p1:Person)-[:ACTED_IN]-(:Movie)-[:ACTED_IN]-(p2:Person)
WHERE p1.name="Kevin Bacon"
RETURN DISTINCT p2;

Upvotes: 2

William Lyon
William Lyon

Reputation: 8546

So you want the relationships to appear in the graph visualization in the Neo4j browser but not store these relationships in the graph itself? I can't think of a way to make that happen (without hacking it), but would deleting the relationships after you are done generating the visual work?

Query to create COSTAR relationships:

MATCH (p1:Person)-[r1:ACTED_IN]-(m1:Movie)-[r2:ACTED_IN]-(p2:Person)
WHERE p1.name="Kevin Bacon"
CREATE UNIQUE (p1)<-[:COSTAR]-(p2);

Execute your query to populate the graph in Neo4j Browser...

Then to delete the COSTAR relationships:

MATCH (:Person)-[r:COSTAR]-(:Person)
DELETE r;

Upvotes: 2

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