4 replies

project("p").by(__.values("a", "b") Only Outputs Single Property, Bug or Expected?

I am curious why this does not behave in the way I expected. Not a problem - solution question.

I created the following Gremlin:

  g.E().
     hasLabel("hiddenFrom").
     inV().
     hasLabel("Person").
     project("Trial", "Site", "Subject ID").
       by(__.out().out().values("tag")).
       by(__.out().values("tag")).
       by(__.values("localId", "uuid"))

  g.E().
     hasLabel("hiddenFrom").
     inV().
     hasLabel("Person").
     project("Trial", "Site", "Subject ID").
       by(__.out().out().values("tag")).
       by(__.out().values("tag")).
       by(__.values("localId", "uuid"))

And in above scenario the

Subject ID

Subject ID

output only outputs the

localId

localId

property but not

uuid

uuid

property. When I change

  by(__.values("localId", "uuid"))

  by(__.values("localId", "uuid"))

  by(__.valueMap("localId", "uuid"))

  by(__.valueMap("localId", "uuid"))

I can get the

uuid

uuid

property value in the output.

A bit surprising that it did not work the way I expected but If it is an expected behavior, then I will remember so from now on. Curious if that is the case why it is designed that way.

Solution

i think the more specific way to answer this question is to say that

by()

by()

modulators only grab the first item in the traversal provided to it so if you want all of them you need to provide your own reducing operator to convert all the items into a single one. typically this is done with

fold()

fold()

 by(__.values("localId", "uuid").fold())

 by(__.values("localId", "uuid").fold())

Jump to solution

Apache TinkerPop•3y ago•

4 replies

Manabu

project("p").by(__.values("a", "b") Only Outputs Single Property, Bug or Expected?

I am curious why this does not behave in the way I expected. Not a problem - solution question.

I created the following Gremlin:

  g.E().
     hasLabel("hiddenFrom").
     inV().
     hasLabel("Person").
     project("Trial", "Site", "Subject ID").
       by(__.out().out().values("tag")).
       by(__.out().values("tag")).
       by(__.values("localId", "uuid"))

  g.E().
     hasLabel("hiddenFrom").
     inV().
     hasLabel("Person").
     project("Trial", "Site", "Subject ID").
       by(__.out().out().values("tag")).
       by(__.out().values("tag")).
       by(__.values("localId", "uuid"))

And in above scenario the

Subject ID

Subject ID

output only outputs the

localId

localId

property but not

uuid

uuid

property. When I change

  by(__.values("localId", "uuid"))

  by(__.values("localId", "uuid"))

  by(__.valueMap("localId", "uuid"))

  by(__.valueMap("localId", "uuid"))

I can get the

uuid

uuid

Solution

i think the more specific way to answer this question is to say that

by()

by()

fold()

fold()

 by(__.values("localId", "uuid").fold())

 by(__.values("localId", "uuid").fold())

Jump to solution

project("p").by(__.values("a", "b") Only Outputs Single Property, Bug or Expected?

project("p").by(__.values("a", "b") Only Outputs Single Property, Bug or Expected?

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