CODEWITHSUNDEEP
neo4jcypher
user1848018
user1848018

Reputation: 1106

Using regular expressions beyond matching in Cypher

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?

Upvotes: 1

Views: 1450

Answers (3)

62mkv
62mkv

Reputation: 1542

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

Upvotes: 0

retrography
retrography

Reputation: 6822

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.

Upvotes: 1

Eve Freeman
Eve Freeman

Reputation: 33175

You can't do that in Cypher (as far as I know)--regex is just for matching.

If it's always just a single letter in front of it, you can take the substring:

start n=node(*) 
set n.userId = substring(n.name, 1)

Upvotes: 1

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