troubleshooting "pseudo-hashes are deprecated" while using xml module - perl

Question

I am just learning how to use perl hashes and ran into this message in perl. I am using XML::Simple to parse xml output and using exists to check on the hash keys.
Message:
Pseudo-hashes are deprecated at ./h2.pl line 53.
Argument "\x{2f}\x{70}..." isn't numeric in exists at ./h2.pl line 53.
Bad index while coercing array into hash at ./h2.pl line 53.
I had the script working earlier with one test directory and then executed the script on another directory for testing when I got this message. How do I resolve/workaround this?
Code that the error references:
use strict;
use warnings;
use XML::Simple;
use Data::Dumper;
#my $data = XMLin($xml);
my $data = XMLin($xml, ForceArray => [qw (file) ]);
my $size=0;
if (exists $data->{class}
and $data->{class}=~ /FileNotFound/) {
print "The directory: $Path does not exist\n";
exit;
} elsif (exists $data->{file}->{path}
and $data->{file}->{path} =~/test-out-00/) {
$size=$data->{file}->{size};
if ($size < 1024000) {
print "FILE SIZE:$size BYTES\n";
exit;
}
} else {
exit;
}
print Dumper( $data );
Working test case, data structure looks like this:
$VAR1 = {
'recursive' => 'no',
'version' => '0.20.202.1.1101050227',
'time' => '2011-09-30T02:49:39+0000',
'filter' => '.*',
'file' => {
'owner' => 'test_act',
'replication' => '3',
'blocksize' => '134217728',
'permission' => '-rw-------',
'path' => '/source/feeds/customer/test/test-out-00',
'modified' => '2011-09-30T02:48:41+0000',
'size' => '135860644',
'group' => '',
'accesstime' => '2011-09-30T02:48:41+0000'
'modified' => '2011-09-30T02:48:41+0000'
},
'exclude' => ''
};
recursive:no
version:0.20.202.1.1101050227
time:2011-10-01T07:06:16+0000
filter:.*
file:HASH(0x84c83ec)
path:/source/feeds/customer/test
directory:HASH(0x84c75d8)
exclude:
Data structure with seeing error:
$VAR1 = {
'recursive' => 'no',
'version' => '0.20.202.1.1101050227',
'time' => '2011-10-03T04:49:36+0000',
'filter' => '.*',
'file' => [
{
'owner' => 'test_act',
'replication' => '3',
'blocksize' => '134217728',
'permission' => '-rw-------',
'path' => '/source/feeds/customer/test/20110531/test-out-00',
'modified' => '2011-10-03T04:47:46+0000',
'size' => '121406618',
'group' => 'feeds',
'accesstime' => '2011-10-03T04:47:46+0000'
},
Test xml file:
<?xml version="1.0" encoding="UTF-8"?><listing time="2011-10-03T04:49:36+0000" recursive="no" path="/source/feeds/customer/test/20110531" exclude="" filter=".*" version="0.20.202.1.1101050227"><directory path="/source/feeds/customer/test/20110531" modified="2011-10-03T04:48:19+0000" accesstime="1970-01-01T00:00:00+0000" permission="drwx------" owner="test_act" group="feeds"/><file path="/source/feeds/customer/test/20110531/test-out-00" modified="2011-10-03T04:47:46+0000" accesstime="2011-10-03T04:47:46+0000" size="121406618" replication="3" blocksize="134217728" permission="-rw-------" owner="test_act" group="feeds"/><file path="/source/feeds/customer/test/20110531/test-out-01" modified="2011-10-03T04:48:04+0000" accesstime="2011-10-03T04:48:04+0000" size="127528522" replication="3" blocksize="134217728" permission="-rw-------" owner="test_act" group="feeds"/><file path="/source/feeds/customer/test/20110531/test-out-02" modified="2011-10-03T04:48:19+0000" accesstime="2011-10-03T04:48:19+0000" size="125452919" replication="3" blocksize="134217728" permission="-rw-------" owner="test_act" group="feeds"/></listing>

Answer 1

The "Pseudo-hashes are deprecated" error means you're trying to access an array as a hash, which means that either $data->{file} or $data->{file}{path} is an arrayref.
You can check the data type by using print ref $data->{file}. The Data::Dumper module may also help you to see what is in your data structure (perhaps while setting $Data::Dumper::Maxdepth = N to limit the dump to N number of levels if the structure is big).
UPDATE
Now that you are using ForceArray, $data->{file} should always point to an arrayref, which may possibly have multiple references to path. Here is a modified segment of your code to handle that. But note that the logic of the if-then-exit conditions may have to change.
if (defined $data->{class} and $data->{class}=~ /FileNotFound/) {
print "The directory: $Path does not exist\n";
exit;
}
exit if ! defined $data->{file};
# filter the list for the first file entry named test-out-00
my ( $file ) = grep {
defined $_->{path} && $_->{path} =~ /test-out-00/
} #{ $data->{file} };
exit if ! defined $file;
$size = $file->{size};
if ($size < 1024000) {
print "FILE SIZE:$size BYTES\n";
exit;
}

Answer 2

When using XML::Simple, the ForceArray option is one of the most important to understand, especially in cases when your input data has nested elements that can occur 1 or more times. For example:
use XML::Simple;
use Data::Dumper;
my #xml_snippets = (
'<opt> <name x="3" y="4">B</name> <name x="5" y="6">C</name> </opt>',
'<opt> <name x="1" y="2">A</name> </opt>',
);
for my $xs (#xml_snippets){
my $data = XMLin($xs, ForceArray => 0);
print Dumper($data);
}
Output:
$VAR1 = {
'name' => [ # Array ref because there are 2 <name> elements.
{
'y' => '4',
'content' => 'B',
'x' => '3'
},
{
'y' => '6',
'content' => 'C',
'x' => '5'
}
]
};
$VAR1 = {
'name' => { # No intermediate array ref.
'y' => '2',
'content' => 'A',
'x' => '1'
}
};
By activating the ForceArray option, you can direct XML::Simple to produce consistent data structures that always use the intermediate array reference, even when there is only 1 of a particular nested element. You can activate the option globally or for specific tags, as illustrated here:
my $data = XMLin($xs, ForceArray => 1 ); # Globally.
my $data = XMLin($xs, ForceArray => [qw(name foo bar)]);

Answer 3

First, I recommend that you use ForceArray => [qw( file )] as previously discussed. That will cause an array to be returned for file, whether there's one or more file element. This is easier to handle than having two possible formats.
As I previously indicated, the problem is that you made no provision for looping over multiple file elements. You said you wanted to exit if the file doesn't exist, so that means you want
my $found;
for my $file (#{ $data->{file} }) {
if ($file->{path} =~ m{/test-out-00\z}) {
$found = $file;
last;
}
}
die("Test file not found\n") if !$found;
... do something with file data in $found ...