user defined steps

[Nikhanj]

Hi 

    How to have an user defined step, returning a map.

   I tried the below code

   Gremlin.defineStep('fn1',[Vertex,Pipe],

   {

reltype,m->_().out(reltype).Name.groupCount(m).iterate();

   });

    

    m=[:];

    g.v(2).fn1('Likes',m);

    But i get class cast exception!!!

    How to resolve this ???

[Stephen Mallette]

You are calling iterate() after groupCount and that is causing that
error. Removing it and simply accessing m after the gremlin has
executed will allow you to get at the count.

If you explicitly want to return the value of the groupCount to the
next step, I guess you could define your step this way:

Gremlin.defineStep('fn', [Vertex, Pipe], { x ->
_().out(x).name.groupCount.cap})

and then do:

gremlin> g = TinkerGraphFactory.createTinkerGraph()
==>tinkergraph[vertices:6 edges:6]
gremlin> \. test.grm
==>null
gremlin> m = g.v(1).fn('created').next()
==>lop=1
gremlin> m
==>lop=1

Does that help?

Stephen

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[Nikhanj]

Hi,

      When you perform  g = TinkerGraphFactory.createTinkerGraph()  , the database that you were pointing before would be lost as you are creating a new instance of g. How will we access the old database now ?? Can't it be achieved without using TinkerGraphFactory ??

[Stephen Mallette]

"g" is just a variable and TinkerGraphFactory.createTinkerGraph(), was
just used for fully demonstrable code. You don't need to create a
TinkerGraph to create a step. Just define your step and use it
against your instance of "g" or whatever variable name you choose.

Stephen

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