How to implement pagination recipe using Golang SDK

[Laura Poss]

Hi all,

I'm trying to implement the pagination recipe using the Golang SDK but am stuck on how to correctly translate the example to Go code.

The code I'm currently working with is as follows:

var __ = gremlingo.T__

g.V().HasLabel("tag").

  Fold().

  As("tags", "count").

  Select("tags", "count").

  By(__.Range(__.Local(), 0, 2).

  By(__.Count(__.Local())).

  ToList()

However, when I run this, I keep getting the following error:

java.lang.IllegalStateException: Could not locate exact method given the supplied arguments: DefaultGraphTraversal.local()

I'm very new to Gremlin and don't have a particularly solid grasp on concepts like anonymous traversals so I'm not sure that I've referenced all of the methods correctly. Any pointers would be greatly appreciated! Thanks!

[Cole Greer]

Hi Laura,

 

There is perhaps some room for improvement when it comes to GLV translations of many of our examples. I believe the correct translation in this case would be this:

results, err := g.V().HasLabel("tag").

     Fold().

     As("tags", "count").

     Select("tags", "count").

     By(__.Range(gremlingo.Scope.Local, 0, 2)).

     By(__.Count(gremlingo.Scope.Local)).

     ToList()

 

I hope this helps.

 

Regards,

 

Cole Greer

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[Yang Xia]

Also just to add, the confusion might have come from the concept of the local Scope (https://tinkerpop.apache.org/docs/current/reference/#a-note-on-scopes) vs the local Step (https://tinkerpop.apache.org/docs/current/reference/#local-step), which have different usage purposes. 

So the "local" in the recipe example is referring to the local Scope, which is why you are getting the illegal state error: both range() and count() are expecting the Scope local instead of the local step. 

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[Laura Poss]

These solutions worked! Thank you so much for the guidance, it's greatly appreciated!