Trouble Parsing XML File Using Perl

问题

I'm trying to parse an XML manifest file for an Articulate eLearning course (imsmanifest.xml).

An excerpt of the XML structure is provided below (I'm trying to drill down to adlcp:masteryscore):

<?xml version="1.0" encoding="UTF-8"?>
<manifest xsi:schemaLocation="http://www.imsproject.org/xsd/imscp_rootv1p1p2 imscp_rootv1p1p2.xsd http://www.imsglobal.org/xsd/imsmd_rootv1p2p1 imsmd_rootv1p2p1.xsd http://www.adlnet.org/xsd/adlcp_rootv1p2 adlcp_rootv1p2.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:adlcp="http://www.adlnet.org/xsd/adlcp_rootv1p2" xmlns="http://www.imsproject.org/xsd/imscp_rootv1p1p2" version="1.0" identifier="Electrical_Design_Part_3">
    <metadata/>
    <organizations default="Electrical_Design_Part_3_ORG">
      <organization identifier="Electrical_Design_Part_3_ORG">
        <title>Electrical Design - Part 3</title>
        <item identifier="Electrical_Design_Part_3_SCO" identifierref="Articulate_Presenter_RES" isvisible="true">
          <title>Electrical Design - Part 3</title>
          <adlcp:masteryscore>65</adlcp:masteryscore>
        </item>
      </organization>
    </organizations>
    <resources/>
</manifest>

I've tried using XML::Simple and XML::LibXML. I can get these modules to work fine with simpler XML files, but not the manifest file I actually need to parse.

The following code shows my attempt to use XML::LibXML to drill down to the title tag:

use XML::LibXML;
$filename = "imsmanifest.xml";
$parser = XML::LibXML->new();
$xmldoc = $parser->parse_file($filename);

for my $sample ($xmldoc->findnodes('/manifest/organizations/organization/item/title')) {
    for my $property ($sample->findnodes('./*')) {
        print $property->nodeName(), ": ", $property->textContent(), "\n";
    }
    print "\n"; 
};

How does one deal with the colon in the adlcp:masteryscore tag? Whenever I try to use this, I get an error - but maybe I'm not doing it right.

Could someone please show me the correct way to drill down to adlcp:masteryscore?

Thank you very much.

回答1:

You're asking to locate elements named manifest in the null namespace, but you want elements named manifest in the http://www.imsproject.org/xsd/imscp_rootv1p1p2 namespace.

Fixes:

use strict;
use warnings;

use XML::LibXML               qw( );
use XML::LibXML::XPathContext qw( );

my $xml_qfn = 'imsmanifest.xml';

my $parser = XML::LibXML->new( no_network => 1 );
my $doc = $parser->parse_file($xml_qfn);

my $xpc = XML::LibXML::XPathContext->new();
$xpc->registerNs( a => "http://www.adlnet.org/xsd/adlcp_rootv1p2" );
$xpc->registerNs( i => "http://www.imsproject.org/xsd/imscp_rootv1p1p2" );

for my $item ($xpc->findnodes('/i:manifest/i:organizations/i:organization/i:item', $doc)) {
    my $title   = $xpc->find('i:title/text()', $item);
    my $mastery = $xpc->find('a:masteryscore/text()', $item);
    print "$title: $mastery\n"; 
}

Note: The actual choice of prefix for use in an XPaths (a and i) is arbitrary. You can pick whatever you want, just like when you compose an XML document.

Note: I added no_network => 1 to prevent libxml from fetching the DTDs every time you parse the XML doc.

回答2:

step one, fix your example so it is properly formed xml

<?xml version="1.0" encoding="UTF-8"?>
<manifest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:adlcp="http://www.adlnet.org/xsd/adlcp_rootv1p2" xmlns="http://www.imsproject.org/xsd/imscp_rootv1p1p2" xsi:schemaLocation="http://www.imsproject.org/xsd/imscp_rootv1p1p2 imscp_rootv1p1p2.xsd http://www.imsglobal.org/xsd/imsmd_rootv1p2p1 imsmd_rootv1p2p1.xsd http://www.adlnet.org/xsd/adlcp_rootv1p2 adlcp_rootv1p2.xsd" version="1.0" identifier="Electrical_Design_Part_3">
    <metadata>
    <organizations default="Electrical_Design_Part_3_ORG">
      <organization identifier="Electrical_Design_Part_3_ORG">
        <title>Electrical Design - Part 3</title>
        <item identifier="Electrical_Design_Part_3_SCO" identifierref="Articulate_Presenter_RES" isvisible="true">
          <title>Electrical Design - Part 3</title>
          <adlcp:masteryscore>65</adlcp:masteryscore>
        </item>
      </organization>
    </organizations>
    <resources/>
</metadata>
</manifest>

fire up the perl debugger

DB<2> use XML::Simple

  DB<3> $x=XMLin("example.xml")

  DB<4> x $x
0  HASH(0x2733c48)
   'identifier' => 'Electrical_Design_Part_3'
   'metadata' => HASH(0x2733828)
      'organizations' => HASH(0x2733288)
         'default' => 'Electrical_Design_Part_3_ORG'
         'organization' => HASH(0x272d7e8)
            'identifier' => 'Electrical_Design_Part_3_ORG'
            'item' => HASH(0x27285f8)
               'adlcp:masteryscore' => 65
               'identifier' => 'Electrical_Design_Part_3_SCO'
               'identifierref' => 'Articulate_Presenter_RES'
               'isvisible' => 'true'
               'title' => 'Electrical Design - Part 3'
            'title' => 'Electrical Design - Part 3'
      'resources' => HASH(0x27333d8)
           empty hash
   'version' => 1.0
   'xmlns' => 'http://www.imsproject.org/xsd/imscp_rootv1p1p2'
   'xmlns:adlcp' => 'http://www.adlnet.org/xsd/adlcp_rootv1p2'
   'xmlns:xsi' => 'http://www.w3.org/2001/XMLSchema-instance'
   'xsi:schemaLocation' => 'http://www.imsproject.org/xsd/imscp_rootv1p1p2 imscp_rootv1p1p2.xsd http://www.imsglobal.org/xsd/imsmd_rootv1p2p1 imsmd_rootv1p2p1.xsd http://www.adlnet.org/xsd/adlcp_rootv1p2 adlcp_rootv1p2.xsd'

  DB<6> x keys %$x
0  'xmlns'
1  'xmlns:xsi'
2  'identifier'
3  'version'
4  'metadata'
5  'xsi:schemaLocation'
6  'xmlns:adlcp'
  DB<9> x keys %{$x->{metadata}}
0  'resources'
1  'organizations'
  DB<10> x keys %{$x->{metadata}{organizations}}
0  'default'
1  'organization'
  DB<11> x keys %{$x->{metadata}{organizations}{organizations}
Missing right curly or square bracket at (eval 22)[/usr/share/perl/5.14/perl5db.pl:640] line 4, at end of line
syntax error at (eval 22)[/usr/share/perl/5.14/perl5db.pl:640] line 4, at EOF
  DB<12> x keys %{$x->{metadata}{organizations}{organizations}}
  empty array
  DB<13> x keys %{$x->{metadata}{organizations}{organization}}
0  'identifier'
1  'item'
2  'title'
  DB<14> x keys %{$x->{metadata}{organizations}{organization}{item}}
0  'identifier'
1  'identifierref'
2  'isvisible'
3  'title'
4  'adlcp:masteryscore'
  DB<19> x $x->{metadata}{organizations}{organization}{item}{'adlcp:masteryscore'}
0  65
  DB<20>

so all you have to do is

use XML::Simple;
$x=XMLIN("example.xml");
print $x->{metadata}{organizations}{organization}{item}{'adlcp:masteryscore'};

Hope this helps

回答3:

the xml is not valid, you need to close the tags metadata and resources

after that XML::Simple will work with this code

#!/usr/bin/env perl 

use strict;
use warnings;
use XML::Simple;
use Data::Dumper;


use XML::Simple qw(:strict);

my $ref = XMLin('test.xml',ForceArray => [], KeyAttr => {});
print STDERR Dumper $ref;

来源：https://stackoverflow.com/questions/15711673/trouble-parsing-xml-file-using-perl

标签

xml

perl

parsing

manifest