Converting hash to json format file [Perl] - perl

Question

So I created a function that creates a hash %data which looks as follows:
{
'10517' => {
'parent' => '10516',
'start' => 1545321095,
'end' => 1545321098,
'name' => 'A'
},
'10515' => {
'parent' => '10513',
'start' => 1545321091,
'end' => 1545321095,
'name' => 'B'
},
'10514' => {
'parent' => '10513',
'start' => 1545321091,
'end' => 1545321095,
'name' => 'C'
},
'10516' => {
'parent' => '10513',
'start' => 1545321091,
'end' => 1545321095,
'name' => 'D',
},
'10511' => {
'parent' => '#####',
'start' => 1545321090,
'end' => 1545321099,
'name' => 'E'
},
'10513' => {
'parent' => '10511',
'start' => 1545321091
'end' => 1545321097
'name' => 'F'
},
'10518' => {
'parent' => '10516',
'start' => 1545321094,
'end' => 1545321098,
'name' => 'G',
},
'10519' => {
'parent' => '10517',
'start' => 1545321096,
'end' => 1545321097,
'name' => 'H',
}
}
I would like to create a function which converts the data into the following output:
{
'children' : [
{
'id' : 10511,
'start' : 1545321090,
'end' : 1545321099,
'name' : 'E'
'children' : [
{
'id' : 10513,
'start' : 1545321091,
'end' : 1545321097,
'name' : 'F'
'children' : [
{
'id' : 10516,
'start' : 1545321091,
'end' : 1545321095,
'name' : 'D'
},
{
'id' : 10514,
'start' : 1545321091,
'end' : 1545321095,
'name' : 'C'
},
{
'id' : 10515,
'start' : 1545321091,
'end' : 1545321095,
'name' : 'B'
},
{
'id' : '10517',
'start' : 1545321095,
'end' : 1545321098,
'name' : 'A'
}
]
}
]
}
],
}
It is not the fully expected data (meaning I was too lazy to add the other ids into the nested format).
I would like to convert the hash %data to be contain a tree-type format as was showen in the example. The final goal is to have a nested data so each parent hash an array of each children, and each one of those children has an array of their own children (if they have of course), and so on.
How should I approch this problem? I'm looking for the cleanest and most effiecnt way possible. Also If possible, without any additional modules.

Answer 1

Just push the child elements into a children array in the parent:
use strict;
use warnings;
use Data::Dumper;
my $data =
{
'10517' => {
'parent' => '10516',
'start' => 1545321095,
'end' => 1545321098,
'name' => 'A'
},
'10515' => {
'parent' => '10513',
'start' => 1545321091,
'end' => 1545321095,
'name' => 'B'
},
'10514' => {
'parent' => '10513',
'start' => 1545321091,
'end' => 1545321095,
'name' => 'C'
},
'10516' => {
'parent' => '10513',
'start' => 1545321091,
'end' => 1545321095,
'name' => 'D',
},
'10511' => {
'parent' => '#####',
'start' => 1545321090,
'end' => 1545321099,
'name' => 'E'
},
'10513' => {
'parent' => '10511',
'start' => 1545321091,
'end' => 1545321097,
'name' => 'F'
},
'10518' => {
'parent' => '10516',
'start' => 1545321094,
'end' => 1545321098,
'name' => 'G',
},
'10519' => {
'parent' => '10517',
'start' => 1545321096,
'end' => 1545321097,
'name' => 'H',
}
};
my $root = [];
for my $id (keys %$data) {
my $entry = $data->{$id};
$entry->{id} = $id;
my $parent = $data->{$entry->{parent}};
unless ($parent){
push #$root, $entry
}
else{
push #{$parent->{children}},$entry;
}
}
print Dumper $root;
see
perldoc perldsc
for an introduction to nested data structures.