CODEWITHSUNDEEP
gremlintinkerpopamazon-neptune
Fook
Fook

Reputation: 5550

Updating a vertex property based on another

I'd like to update a highScore based on a users score when it is incremented. If the newly incremented score is greater than highScore, set highScore = score.

// initial data
g.addV("player")
  .property(id, 1)
  .property(single, "score", 0)
  .property(single, "highScore", 0)

// increment score by 1 and set highScore if required
g.V(1)
  .sack(assign)
  .by("score")
  .sack(sum)
  .by(__.constant(1))
  .property(single, "score", sack())
  .choose(
    __.values("highScore").is(lt(__.values("score"))),
    __.property(single, "highScore", __.values("score")))
  )

It seems to error on lt(__.values("score")). It's parsing that as a traversal instead of a value.

com.amazon.neptune.tinkerpop.structure.NeptuneGraph$NeptuneGraphTraversal cannot be cast to java.lang.Integer

How can I pass the current value of score into that predicate? I've tried adding .value(), .iterate(), and .next()

Upvotes: 0

Views: 488

Answers (1)

stephen mallette
stephen mallette

Reputation: 46206

This approach using where() seems to work:

gremlin> g.V(1).as('a').
......1>   sack(assign).
......2>     by("score").
......3>   sack(sum).
......4>     by(__.constant(1)).
......5>   property(single, "score", sack()).
......6>   choose(where('a', lt('a')).by('highScore').by('score'),
......7>          __.property(single, "highScore", sack()))
==>v[1]
gremlin> g.V().valueMap()
==>[score:[1],highScore:[1]]
gremlin> g.V(1).as('a').
......1>   sack(assign).
......2>     by("score").
......3>   sack(sum).
......4>     by(__.constant(1)).
......5>   property(single, "score", sack()).
......6>   choose(where('a', lt('a')).by('highScore').by('score'),
......7>          __.property(single, "highScore", sack()))
==>v[1]
gremlin> g.V().valueMap()
==>[score:[2],highScore:[2]]
gremlin> g.V().property('highScore',10)
==>v[1]
gremlin> g.V().valueMap()
==>[score:[2],highScore:[10]]
gremlin> g.V(1).as('a').
......1>   sack(assign).
......2>     by("score").
......3>   sack(sum).
......4>     by(__.constant(1)).
......5>   property(single, "score", sack()).
......6>   choose(where('a', lt('a')).by('highScore').by('score'),
......7>          __.property(single, "highScore", sack()))
==>v[1]
gremlin> g.V().valueMap()
==>[score:[3],highScore:[10]]

Upvotes: 1

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