Using regular expressions beyond matching in Cyphe

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

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)

Answer 2

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.