CODEWITHSUNDEEP
neo4jcypher
Pradeep
Pradeep

Reputation: 3276

Neo4J checking if a user follows me back

I am building a follower model with neo4j. User A [:Follows] -> user B and user B can do the same.

A is follower of B. Getting this information is straight forward. However I also want to get information at the same time if B [:Follows] -> A or not.

Is there a way to pull out this information?

Upvotes: 0

Views: 80

Answers (2)

Graphileon
Graphileon

Reputation: 5385

this query will give you the followers of A and a true|false for each of them indicating if (s)he follows back

MATCH (ua:User {name:"bob"})-[:Follows]->(ub:User)
RETURN ub.name AS ubName,
       EXISTS((ub)-[:Follows]->(ua)) AS followsBack

Upvotes: 1

Steve Mapes
Steve Mapes

Reputation: 921

You can do it by adding an OPTIONAL MATCH of the reverse path and then assigning this path to a variable. Then you test the length of the variable in the RETURN using a CASE statement to get the results

E.G.

MATCH (ua:User {name:"bob"})-[:Follows]->(ub:User {name:"Bill"})
OPTIONAL MATCH p = (ub)-[r:Follows]->(ua)
RETURN ua.name, ub.name, CASE WHEN LENGTH(p) > 0 THEN 'yes' ELSE 'no' END AS follows_back

This would return either: "bob", "bill", "yes" or "bob", "bill", "no"

Upvotes: 1

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