How can I extract attributes from repeated tags in XML using Perl?

Question

I am trying to parse a set of XML files. The XML file may have single flag tag or multiple flag tags:

<job>   <flag exit="0">aaa</flag> </job>

OR

<job>
  <flag exit="0">aaa</flag>
  <flag exit="1">bbb</flag>
  <flag exit="2">ccc</flag>
</job>

But determining this "flag" count has to be determined on the fly. What's the best way to determine the flag count and print the values in it?

Answer 1

use XML::Simple;
use Data::Dumper;

# This reads the data after the __DATA__ pragma
# into an array, which is then joined with no spaces
# to build the string $xml    
my $xml = join '', <DATA>;

# XMLin takes a filename, string or an IO::Handle object
# and slurps that data appropriately into a hash structure
my $config = XMLin($xml);

# Just look at the structure...
# print Dumper $config;

my $tag_count = @{$config->{flag}};

# As suggested in a comment below, 
# an alternative is to force the structure to be array based
# even for single elements, with XMLin($xml, ForceArray => 1);
if ($tag_count > 1) {
    print $_->{content}, q{ } for @{$config->{flag}}; # => aaa bbb ccc
    print $_->{exit},    q{ } for @{$config->{flag}}; # => 0 1 2
}
else {
    print $config->{flag}{content}; # => aaa
    print $config->{flag}{exit};    # => 0
}


__DATA__
<job>
    <flag exit="0">aaa</flag>
    <flag exit="1">bbb</flag>
    <flag exit="2">ccc</flag>
</job>

Answer 2

You can use XML::Simple's ForceArray option to force every tags or some tags to be extracted in array.