g.V(id).property(Cardinality, key, arrayValue) bugged?

[Thomas Driessen]

Hi,

I'm not sure if this is a bug or if I'm using this method incorrectly, so here's what I've done:

When I call

   g.V(someid).property(Cardinality.list, "test", new String[]{"value1", "value2"})

I receive an java.lang.IllegalArgumentException: The provided key/value array length must be a multiple of two

However if I'm doing the same without explicitly stating the Cardinality like this:

   g.V(someId).property("test", new String[]{"value1", "value2"})

the property is added as expected and I also get the array back when I query it.

Is this a bug or am I doing something wrong?

Gremlin version I'm using: 3.4.4

Kind regards,

Thomas

[Stephen Mallette]

Your String[] is being interpreted as varargs which become meta-properties:

gremlin> g.addV().property(VertexProperty.Cardinality.list, "test", ["value1", "value2"] as String[])

The provided key/value array length must be a multiple of two

Type ':help' or ':h' for help.
Display stack trace? [yN]n
gremlin> g.addV().property(VertexProperty.Cardinality.list, "test", ["value1", "value2","value3"] as String[])
==>v[0]
gremlin> g.V().properties('test')
==>vp[test->value1]
gremlin> g.V().properties('test').properties()
==>p[value2->value3]

I suppose the question is, are you trying to do multi-properties of two strings "value1" and "value2" or are you doing multi-properties of String[]. If the former then:

gremlin> g.addV().property(VertexProperty.Cardinality.list, "test", "value1").property(VertexProperty.Cardinality.list, "test", "value2")
==>v[0]
gremlin> g.V().properties('test')
==>vp[test->value1]
==>vp[test->value2]

If the latter then I would probably try to store it as a List<String> rather than String[]. 

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[Thomas Driessen]

I was trying the latter ;)

As always: thanks for your quick answer :) 

Kind regards,

Thomas

Am Freitag, 26. Juni 2020 15:44:00 UTC+2 schrieb Stephen Mallette:

Your String[] is being interpreted as varargs which become meta-properties:

gremlin> g.addV().property(VertexProperty.Cardinality.list, "test", ["value1", "value2"] as String[])
The provided key/value array length must be a multiple of two
Type ':help' or ':h' for help.
Display stack trace? [yN]n
gremlin> g.addV().property(VertexProperty.Cardinality.list, "test", ["value1", "value2","value3"] as String[])
==>v[0]
gremlin> g.V().properties('test')
==>vp[test->value1]
gremlin> g.V().properties('test').properties()
==>p[value2->value3]

I suppose the question is, are you trying to do multi-properties of two strings "value1" and "value2" or are you doing multi-properties of String[]. If the former then:

gremlin> g.addV().property(VertexProperty.Cardinality.list, "test", "value1").property(VertexProperty.Cardinality.list, "test", "value2")
==>v[0]
gremlin> g.V().properties('test')
==>vp[test->value1]
==>vp[test->value2]

If the latter then I would probably try to store it as a List<String> rather than String[]. 

On Fri, Jun 26, 2020 at 9:08 AM Thomas Driessen <thomas.d...@gmail.com> wrote:

Hi,

I'm not sure if this is a bug or if I'm using this method incorrectly, so here's what I've done:

When I call

   g.V(someid).property(Cardinality.list, "test", new String[]{"value1", "value2"})

I receive an java.lang.IllegalArgumentException: The provided key/value array length must be a multiple of two

However if I'm doing the same without explicitly stating the Cardinality like this:

   g.V(someId).property("test", new String[]{"value1", "value2"})

the property is added as expected and I also get the array back when I query it.

Is this a bug or am I doing something wrong?

Gremlin version I'm using: 3.4.4

Kind regards,

Thomas

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[thomas.dr...@gmail.com]

Uhm maybe a small follow-up question:

If I'm storing list properties by  g.addV().property(VertexProperty.Cardinality.list, "test", "value1").property(VertexProperty.Cardinality.list, "test", "value2")  

Is there then a common pattern on how to retrieve lists back as lists and single values back as single values?

Usually I used g.V(someid).valueMap().by(__.unfold()), but this would unfold also lists and only return the first value.

I also thought of g.V(someId).valueMap().by(__.choose(__.count(Scope.local).is(1), __.unfold(), __.identity()))

but this would turn single valued lists into single values...

Any advice is appreciated :)

[Stephen Mallette]

Gremlin doesn't know anything about your schema so you would have to deal with such things manually:

gremlin> g.V().project('name','test').
......1>         by('name').
......2>         by(values('test').fold())
==>[name:thomas,test:[value1,value2]]

We tend to discuss this as a best practice in the sense that we like to see Gremlin that is explicit in terms of the data it returns. In much the same way you don't write SELECT * FROM table in SQL you typically don't want to valueMap() too conveniently. 

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[thomas.dr...@gmail.com]

Thanks!