Decoding JSON in Perl

Question

I have a JSON file like this one (it is a piece of the entire JSON file):

{
  id => "mgp1310",
  samples => [
    {
      envPackage => {
        data => {
          diss_carb_dioxide => {
            aliases    => ["sediment_diss_carb_dioxide"],
            definition => "concentration of dissolved carbon dioxide",
            mixs       => 1,
            required   => 0,
            type       => "text",
            unit       => "",
            value      => "17 mM",
          },
        },
        id => "mge64559",
      },
    },
  ],
}

This has been decoded by module JSON, using:

use Data::Dumper;
use JSON;

open($fh, '<', 'hola.txt' );
$json_text   = <$fh>;
$perl = decode_json($json_text);
print Dumper($perl);

Now I know that $perl has a hash. So I'd like to print the id of the JSON file using print $perl{"id"};. However, it prints nothing I don't know why.

Never something so simple was so useful... – user2979409 Sep 26 '14 at 10:53 — user2979409, Sep 26 '14 at 10:53
`use warnings;` is real useful too. – Bill Ruppert Sep 27 '14 at 02:42 — Bill Ruppert, Sep 27 '14 at 02:42

score 5 · Answer 1 · answered Sep 26 '14 at 10:56

I found the answer by adding use strict at my code. It threw the following error:

Global symbol "%perl" requires explicit package name at json.pl line 12.

The variable $perl is a scalar, not a hash!. Of course... I didn't thought about that. So I cannot access to the hash writing $perl{"id"}. The correct way is $perl->{id}.

Decoding JSON in Perl

1 Answers1