use strict;
use warnings;

binmode STDOUT, ":utf8";
use utf8;

use JSON;

my $json ={
	'book' => {
		'title' => 'smth',
		'num_page' => 234
	}
};

my $data = decode_json($json);
open my $fh, ">", "data_out.json";
print $fh encode_json($data);
close $fh;