Iterating Through Array Of Hash References In Perl?

Question

I am using XML::Simple to load some XML into a data structure which basically contains file/directory information. The problem I am having is iterating through the resulting data structure. I can get to the data I need by using the following:

$lsResults->{file}

If I dump that structure using Dumper, what I see is something like:

$VAR1 = [
          {
            'owner' => 'reps_hd',
            'replication' => '3',
            'blocksize' => '134217728',
            'permission' => '-rw-r-----',
            'path' => '/projects/mdataeng/feeds/customer_care/mail_q_grid_data_20110816.dat',
            'modified' => '2011-08-18T21:41:11+0000',
            'size' => '625182',
            'group' => 'mdataeng',
            'accesstime' => '2011-08-18T21:41:11+0000'
          },
          {
            'owner' => 'reps_hd',
            'replication' => '3',
            'blocksize' => '134217728',
            'permission' => '-rw-r--r--',
            'path' => '/projects/mdataeng/feeds/customer_care/mail_q_grid_data_20110817.dat',
            'modified' => '2011-08-19T23:29:06+0000',
            'size' => '600199',
            'group' => 'mdataeng',
            'accesstime' => '2011-08-19T23:29:06+0000'
          }, 
   ....

Isn't this basically an array of hash references? I know I can reference the data in the first element by doing:

print Dumper($lsResults->{file}[0]);

$VAR1 = {
          'owner' => 'reps_hd',
          'replication' => '3',
          'blocksize' => '134217728',
          'permission' => '-rw-r-----',
          'path' => '/projects/mdataeng/feeds/customer_care/mail_q_grid_data_20110816.dat',
          'modified' => '2011-08-18T21:41:11+0000',
          'size' => '625182',
          'group' => 'mdataeng',
          'accesstime' => '2011-08-18T21:41:11+0000'
        };

So, the question is, how do I iterate through all of the results in the $lsResults->{file} structure to get say the "path" key value for each entry? I know I could manually reference this by doing something like:

print $lsResults->{file}[0]->{path};
print $lsResults->{file}[1]->{path};
print $lsResults->{file}[2]->{path};
print $lsResults->{file}[3]->{path};

But I can't seem to figure out how to iterate through

$lsResults->{file}

What exactly am I doing wrong here?

Lucas · Accepted Answer · 2019-01-29 14:59:41Z

6

Try this:

for my $file ( @{$lsResults->{file}} ) {
    print $file->{path};
}

The variable $lsResults->{file} is actually an array reference, not an array, so you have to de-reference it to iterate over it with the for loop.

edited Jan 29, 2019 at 14:59

answered Oct 6, 2011 at 17:16

Lucas

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Platinum Azure · Accepted Answer · 2011-10-06 17:27:25Z

1

You can also use map to get a list transformation:

use strict;
use warnings;

my @allPaths = map {$_->{path}} @{$lsResults->{file}}

print "$_\n" foreach @allPaths;

answered Oct 6, 2011 at 17:27

Platinum Azure

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