Using regular expressions beyond matching in Cypher

Question

I make the following query

neo4j-sh (?)$ start n=node(*) where n.name  =~ 'u(.*)' return n; 
==> +-----------------------+
==> | n                     |
==> +-----------------------+
==> | Node[311]{name:"u1"}  |
==> | Node[312]{name:"u2"}  |
==> | Node[313]{name:"u3"}  |
==> | Node[314]{name:"u4"}  | 

I want to add a "userId" property and set it the number in the name key. I mean I want

==> +-----------------------+
==> | n                     |
==> +-----------------------+
==> | Node[311]{name:"u1", userId:'1'}  |
==> | Node[312]{name:"u2", userId:'2'}  |
==> | Node[313]{name:"u3"},userId:'3'  |
==> | Node[314]{name:"u4"}, userId:'4' | 

Now I need to strip the numbers from n.name. How can I do this? How can I get the value from the (.*) in regex?

Answer 1

I had the same issue, so I developed a tiny Neo4j server plugin that lets you run regular expressions over REST API and against string node properties for matching/splitting/substituting purposes. It can return the results inside Neo4j console or save them to a property.

Have a look at it, maybe you find it useful: https://github.com/mszargar/Regx4Neo

It takes just a minute to install, but you will have to restart Neo4j for it to take effect.

Answer 2

You should be able to use matched groups with an APOC apoc.text.regexGroups function:

MATCH (a:AppJar)-[:CONTAINS]->(b)
WHERE b.fileName STARTS WITH "/BOOT-INF/lib/event-"
WITH a, b, last(last(apoc.text.regexGroups(b.fileName, '/BOOT-INF/lib/event-([\\d\\.]+).jar'))) as version
SET b.version = version
RETURN a.appName, b.fileName, b.version
LIMIT 100

it is a different query but should be applicable to your data as well