How gremlin has step with a regex?

[pengzhi...@gmail.com]

Hello, 

       I want to filter vertex with has step, when vertex property value meets a regex, how to do it? like g.V().has("name", "^marko")  find all vertices when property 'name' start with 'marko'.

[Daniel Kuppitz]

TinkerPop doesn't support RegEx matching out of the box. Some implementations (Titan and DSE Graph) do have some extra predicates though.

However, it's easy to implement your own predicate:

gremlin> regexBiPredicate = new java.util.function.BiPredicate<String, String>() {
......1>   boolean test(String value, String pattern) {
......2>     return value ==~ pattern
......3>   }
......4> }
==>groovysh_evaluate$1@43f9dd56

gremlin> regex = {
......1>   new P(regexBiPredicate, it)
......2> }
==>groovysh_evaluate$_run_closure1@354e7004

gremlin> g = TinkerFactory.createModern().traversal()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g.V().has("name", regex(/mark.*/))
==>v[1]

If startsWith(...) is all you need, you can also use a simpler solution:

gremlin> g.V().has("name", between("marko", "markp"))
==>v[1]

Cheers,

Daniel

On Fri, Jan 6, 2017 at 11:03 AM, <pengzhi...@gmail.com> wrote:

Hello, 

       I want to filter vertex with has step, when vertex property value meets a regex, how to do it? like g.V().has("name", "^marko")  find all vertices when property 'name' start with 'marko'.

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[Praneeth Dogiparthi]

Thanks for the solution it worked but what if we filter over multiple properties 

for example :  g.V().has("name", between("marko", "markp")) . this only returns vertices matching marko for property name.

But what if we need to get all vertices who firstname or lastname that contains marko . the above example only searches for only one property but we need to search for whether marko is present in firstname or lastname both properties. can you help. Thanks in advance. 

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[Daniel Kuppitz]

Well, you can use the or() step:

g.V().or(has("firstname", "marko"), has("lastname", "marko"))

 ...or just execute 2 traversals in parallel. Depending on your graph provider and how these properties are indexed, one approach may perform much better than the other.

Cheers,

Daniel

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