hash-array-hash confused

mitchreward has asked for the wisdom of the Perl Monks concerning the following question:

Hi guys,

Am still pretty new to perl and I'd like to parse a JSON object. I'm lost between hash in arrays ...

my $json = JSON->new;
my $data = $json->decode($res);

my @result = $data->{'results'};
print Dumper @result;
[download]

Here is the output of data Dumper

$VAR1 = [
          {
            'closed_at' => 1404289092,
            'elapsed_resolution_first' => '61511',
            'num_messages' => '4',
            'owner__context' => 'cerberusweb.contexts.worker',
            'latest_message__context' => 'cerberusweb.contexts.message
+',
            'latest_message_id' => 4540513,
            'bucket_id' => 0,
          }
         {
            'closed_at' => 1404289092,
            'elapsed_resolution_first' => '61511',
            ....
          }
        ]
[download]

So I guess this is several hash in an array, am I wrong ? And then I'd like to itterate all 'closed at' with a foreach. Any help to do this ? I've read like 4 times the perldoc on references, and Im even more confuse now.

Thanks guys

Comment on hash-array-hash confused Select or Download Code

Replies are listed 'Best First'.
Re: hash-array-hash confused by AppleFritter (Vicar) on Jul 17, 2014 at 16:04 UTC
Howdy mitch, welcome back to the Monastery! You're almost right. It's several hashes in an array indeed, but `$data->{'results'}` is itself an array reference, so in your example, `@result` is a one-element list (i.e. array) containing a single reference to an anonymous array containing several anonymous hashes. In order to iterate through all these, your best bet is to dereference the outermost array reference, obtaining the array of hashes again, then iterating through its elements (the hashes) and looking at each hash's `closed_at` key, like this: `... my $result_ref = $data->{'results'}; my @result = @$result_ref; foreach my $hash_ref (@result) { say "closed_at: ", $hash_ref->{'closed_at'}; ... }` [download] Of course, you don't have to save `$result_ref` and `@result` unless you need them. The `foreach` loop could also be written this way: `... foreach my $hash_ref (@{ $data->{'results'} }) { ... }` [download] The result's the same, but the above will perhaps make it a little more clear what's going on.	[reply] [d/l] [select]
Re^2: hash-array-hash confused by mitchreward (Acolyte) on Jul 18, 2014 at 06:44 UTC
thank you both, for the quality of our answers!	[reply]
Re: hash-array-hash confused by toolic (Bishop) on Jul 17, 2014 at 15:24 UTC
Here's one way: `use warnings; use strict; my $VAR1 = [ { 'closed_at' => 1404289092, 'elapsed_resolution_first' => '61511', 'num_messages' => '4', 'owner__context' => 'cerberusweb.contexts.worker', 'latest_message__context' => 'cerberusweb.contexts.message +', 'latest_message_id' => 4540513, 'bucket_id' => 0, }, { 'closed_at' => 1404289092, 'elapsed_resolution_first' => '61511', } ]; my @result = @{ $VAR1 }; for my $href (@result) { print "$href->{closed_at}\n"; } __END__ 1404289092 1404289092` [download] See also perldsc	[reply] [d/l]