$parent and $ current in orientDB query

Question

I read it on orientDB documentation but can't get a hold of it. It would be great if someone could explain the use of $parent and $current in detail. In a few examples I tried $parent.$parent.$current and $parent.$current, both give the same results which I feel should not happen. Below are my assumption:

1. $current gives access to the record/node currently being processed
2. $parent gives access to the parent of current record/node being processed

Answer 1

Your second assumption is wrong. It gives you access to the variables of the parent query (useful when calling traverse in a sub-query as stated here).

An example:

create class User extends V    
create class Follows extends E

create vertex User set name = 'u1'
create vertex User set name = 'u2'
create vertex User set name = 'u3'    

create edge Follows from (select from User where name = 'u1') to (select from User where name = 'u2')
create edge Follows from (select from User where name = 'u2') to (select from User where name = 'u3')


select $all from User
let $all = ( traverse out('Follows') from $parent.$current)