I have a neo4j query like:
...
"WITH DISTINCT k " +
// classic for each loop for the new rankings information
"FOREACH (app in $apps | " +
// upsert the app
" MERGE (a:App{appId:app.appId}) " +
...
// end of loop
") " +
I'm using gremlin-java. In here, I want to give $apps as custom parameter. I've just checked gremlin document but I couldn't find a foreach step. Is there a suggestion?
graph.foreach(apps: map)...
Solved with:
...constant($apps).unfold().as(app)...
As you noted you can use a constant step to inject a value into a query. However you can also use the inject step to insert a collection of values in a similar way. Here are a couple of simple examples - you can extend these patterns to include id, label and multiple property values as needed.
gremlin> g.inject([[id:1],[id:2],[id:3],[id:4]]).
unfold().as('a').
addV('test').
property('SpecialId',select('a').select('id'))
==>v[61367]
==>v[61369]
==>v[61371]
==>v[61373]
gremlin> g.V().hasLabel('test').valueMap(true)
==>[id:61367,label:test,SpecialId:[1]]
==>[id:61369,label:test,SpecialId:[2]]
==>[id:61371,label:test,SpecialId:[3]]
==>[id:61373,label:test,SpecialId:[4]]
gremlin> g.inject(1,2,3,4).as('a').
addV('test2').
property('SpecialId',select('a'))
==>v[61375]
==>v[61377]
==>v[61379]
==>v[61381]
gremlin> g.V().hasLabel('test2').valueMap(true)
==>[id:61375,label:test2,SpecialId:[1]]
==>[id:61377,label:test2,SpecialId:[2]]
==>[id:61379,label:test2,SpecialId:[3]]
==>[id:61381,label:test2,SpecialId:[4]]
gremlin>
The first query injects a list of maps. The second a simple list. This is a bit like the UNWIND pattern you may be used to in Cypher and it works in a similar way.