Re: "Beginner" question on parsing XML file with XML::Simple

From: Johan Landerholm <[email protected]>
> I have just come across a XML parsing problem that I thought perl would 
> be good in solving for me.
> But, I have struggled with the XML::Simple module to get the information 
> from a xml report that I get from a system.
> 
> If someone is willing to help me with this problem, I would be very 
> thankful!
> 
> I have a report that I need to pull a few pieces of data from and do 
> something else with.
> The report looks like this:
> 
> 
> <?xml version="1.0" encoding="UTF-8"?>
> <ReportOutput>
>     <ReportHead>
>         <Report oid="-1y2p0ij32e7uh:-1y2p0ij30wn8z" name="export log" 
> type="systemlog_rpt">
>             <Description>Test report</Description>
>         </Report>
>     </ReportHead>
>     <ReportBody>
>         <ReportSection name="messages" category="messages">
>             <ReportSection name="12/14/08 7:15 AM" category="message">
>                 <String name="user">administrator</String>
>                 <Timestamp name="messageTime" displayvalue="12/14/08 
> 7:15 AM">1229267714000</Timestamp>
>                 <String name="message">Modified Rule 'test rule'.
> 
> Added '/bin'.
> </String>
>                 <String name="level">Information</String>
>                 <String name="category">Rule Change</String>
>             </ReportSection>
>         </ReportSection>
>         <ReportSection name="reportTotals" category="reportTotals">
>             <Integer name="summary.messages">1</Integer>
>             <Integer name="summary.information">1</Integer>
>             <Integer name="summary.error">0</Integer>
>         </ReportSection>
>     </ReportBody>
> </ReportOutput>
> 
> The information that I need is the <String 
> name="user">*administrator*</String> and the <String 
> name="message">*Modified Rule 'test rule'. Added '/bin'.*</String>.
> How is it possible to find this information in a perl script ?
> I have tried to use the examples in the documentation but I can't get it 
> right ?

You may use XML::Rules. And either transform the data into a 
datastructure that'll fit your needs or print the stuff you need as 
you go along:


use strict;
use XML::Rules;

my $parser = XML::Rules->new(
  stripspaces => 7,
  start_rules => {
    ReportHead => 'skip',
    ReportSection => sub {
      if ($_[1]->{category} eq 'messages') {
          # nothing to write at the end of the messages ReportSection
          print "Writing messages from the report section '$_[1]-
>{name}'\n\n";
      }
      return 1;
    },
  },
  rules => {
    'String,Integer' => sub {return '_'.$_[1]->{name} => $_[1]-
>{_content}},
    'Timestamp' => sub {return '_'.$_[1]->{name} => $_[1]-
>{displayvalue}},
    'ReportSection' => sub {
      if ($_[1]->{category} eq 'message') {
        print "The message at $_[1]->{name} written by $_[1]->{_user} 
at $_[1]->{_messageTime} was:
$_[1]->{_message}\n\n";
      } elsif ($_[1]->{category} eq 'messages') {
        # nothing to write at the end of the messages ReportSection
      } elsif ($_[1]->{category} eq 'reportTotals') {
        print "There were $_[1]->{'_summary.messages'} messages.\n";
      } else {
        print "Unknown category '$_[1]->{category}'\n";
      }
      return;
    },
  },
);

$parser->parse(\*DATA);

__DATA__
<?xml version="1.0" encoding="UTF-8"?>
<ReportOutput>
    <ReportHead>
        <Report oid="-1y2p0ij32e7uh:-1y2p0ij30wn8z" name="export log" 
type="systemlog_rpt">
            <Description>Test report</Description>
        </Report>
    </ReportHead>
    <ReportBody>
        <ReportSection name="messages" category="messages">
            <ReportSection name="12/14/08 7:15 AM" 
category="message">
                <String name="user">administrator</String>
                <Timestamp name="messageTime" displayvalue="12/14/08 
7:15 AM">1229267714000</Timestamp>
                <String name="message">Modified Rule 'test rule'.

Added '/bin'.
</String>
                <String name="level">Information</String>
                <String name="category">Rule Change</String>
            </ReportSection>
        </ReportSection>
        <ReportSection name="reportTotals" category="reportTotals">
            <Integer name="summary.messages">1</Integer>
            <Integer name="summary.information">1</Integer>
            <Integer name="summary.error">0</Integer>
        </ReportSection>
    </ReportBody>
</ReportOutput>

===== [email protected] === http://Jenda.Krynicky.cz =====
When it comes to wine, women and song, wizards are allowed 
to get drunk and croon as much as they like.
	-- Terry Pratchett in Sourcery

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