Yshyeeni has asked for the wisdom of the Perl Monks concerning the following question:

I am trying to add an attribute to existing XML, using XML::LibXML.

    <arbre>
      <branche name="courbe" >
        <description>
          <![CDATA[une belle branche]]>
        </description>
        <feuilles>
          <fleur color="blue" order="1" />
          <fleur color="white" order="2" />
          <fleur color="yellow" order="3" />
        </feuilles>
      </branche>
      <branche name="droite" >
        <description>
          <![CDATA[une branche commune]]>
        </description>
        <feuilles>
          <fleur color="purple" order="1" />
          <fleur color="green" order="2" />
        </feuilles>
      </branche>
    </arbre>

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That I am trying to transform into :

    <arbre>
      <branche name="courbe" type="conifere">
        <description>
          <![CDATA[une belle branche]]>
        </description>
        <feuilles>
          <fleur color="blue" order="1" />
          <fleur color="white" order="2" />
          <fleur color="yellow" order="3" />
        </feuilles>
      </branche>
      <branche name="droite" type="resineux">
        <description>
          <![CDATA[une branche commune]]>
        </description>
        <feuilles>
          <fleur color="purple" order="1" />
          <fleur color="green" order="2" />
        </feuilles>
      </branche>
    </arbre>

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Notice the type attribute in branche tag.
So far I have the following :

    #!/usr/bin/env perl -w
    
    use strict;
    use XML::LibXML;
    
    $parser = XML::LibXML->new();
    $dom    = $parser->load_xml();
    # now I do what?
    exit 0;

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I know how to do this with XML::Simple, but someone told me that the use of this librairie is not recommended.
Which might be true because I have encodings and stripped CDATA problems

From what I understand from the documentation $dom is a document object which has a method called createAttribute that I might be able to use.
Any solution?.
Thanks

Replies are listed 'Best First'.
Re: Add attribute to xml with XML::LibXML
by Loops (Curate) on Jul 30, 2013 at 14:11 UTC

    Create an iterator, pass over each element looking for 'branche' nodes, and update them when found:

    use strict;
use warnings;
use XML::LibXML;
use XML::LibXML::Iterator;

my $parser = XML::LibXML->new();
my $dom    = $parser->load_xml(location => 'input.xml');

my %newtypes = ( courbe => 'conifere', droite => 'resineux' );

my $iter = XML::LibXML::Iterator->new( $dom->documentElement );
while ( $iter->nextNode() ) {
     my $node = $iter->current();
     next unless $node->nodeName eq 'branche';
     $node->setAttribute( 'type',
        $newtypes{$node->getAttribute('name')} );
}

print $dom->toString;
exit 0;

    [download]
    produces: 
    <?xml version="1.0"?>
<arbre>
    <branche name="courbe" type="conifere">
        <description>
            <![CDATA[une belle branche]]>
        </description>
        <feuilles>
            <fleur color="blue" order="1"/>
            <fleur color="white" order="2"/>
            <fleur color="yellow" order="3"/>
        </feuilles>
    </branche>
    <branche name="droite" type="resineux">
        <description>
            <![CDATA[une branche commune]]>
        </description>
        <feuilles>
            <fleur color="purple" order="1"/>
            <fleur color="green" order="2"/>
        </feuilles>
    </branche>
</arbre>

    [download]
[reply]
[d/l]
[select]

      FYI, if your version of XML::LibXML is vaguely recent (since 1.9x), then this:

      $node->setAttribute( 'type',
        $newtypes{$node->getAttribute('name')} );

      [download]

      Can be written as:

      $node->{type} = $newtypes{ $node->{name} };

      [download]

      That is, XML::LibXML::Element acts like a hashref, and you can get/set attributes that way.

      package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name
[reply]
[d/l]
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Re: Add attribute to xml with XML::LibXML
by daxim (Curate) on Jul 30, 2013 at 13:49 UTC
[reply]

      Yes, but my question was answered and editing it seemed an ugly choice.

[reply]
Re: Add attribute to xml with XML::LibXML
by ikegami (Patriarch) on Jul 31, 2013 at 01:35 UTC
    Or using XPaths: 
    use strict;
use warnings;
use XML::LibXML;

my $parser = XML::LibXML->new();
my $doc    = $parser->load_xml(location => 'input.xml');

my %types = ( courbe => 'conifere', droite => 'resineux' );

for my $branch_node ($doc->findnodes('/arbre/branche')) {
    $branch_node->setAttribute(type => $types{$branch_node->getAttribu
+te('name')});
}

print $doc->toString;

    [download]
[reply]
[d/l]
Re: Add attribute to xml with XML::LibXML
by Yshyeeni (Initiate) on Jul 31, 2013 at 13:24 UTC

    Hi,
    Thanks for your help.
    For your information (or future readers), I had to take two xml files, add attributes to them xml and join them.

    For example :

    File1 had:

        <?xml version="1.0" encoding="UTF-8"?>
    <arbre>
      <branche name="courbe" >
        <description>
          <![CDATA[une belle branche]]>
        </description>
        <feuilles>
          <fleur color="blue" order="1" />
          <fleur color="white" order="2" />
          <fleur color="yellow" order="3" />
        </feuilles>
      </branche>
      <!--etc...-->
    </arbre>

    [download]

    File2 had :

        <?xml version="1.0" encoding="UTF-8"?>
    <arbre>
      <branche name="droite" >
        <description>
          <![CDATA[une branche commune]]>
        </description>
        <feuilles>
          <fleur color="purple" order="1" />
          <fleur color="green" order="2" />
        </feuilles>
      </branche>
      <!--etc...-->
    </arbre>

    [download]

    And the expected result was

        <arbre>
      <branche name="courbe" type="conifere">
        <description>
          <![CDATA[une belle branche]]>
        </description>
        <feuilles>
          <fleur color="blue" order="1" />
          <fleur color="white" order="2" />
          <fleur color="yellow" order="3" />
        </feuilles>
      </branche>
      <!--etc...-->
      <branche name="droite" type="resineux">
        <description>
          <![CDATA[une branche commune]]>
        </description>
        <feuilles>
          <fleur color="purple" order="1" />
          <fleur color="green" order="2" />
        </feuilles>
      </branche>
      <!--etc...-->
    </arbre>

    [download]

    Here is the code :

    sub _mergeXML
{
    my $FILE1   = shift;
    my $FILE2   = shift;
    my $FILEOUT = shift;

    my $parser = XML::LibXML->new();
    my @wanted;

    my $genericDom = $parser->load_xml(location => $FILE1);
    for my $branch_node ($genericDom->findnodes("/arbre/branche"))
    { $branch_node->setAttribute(type => "conifere"); }
    push(@wanted, $genericDom->documentElement->findnodes("./*"));

    my $customDom = $parser->load_xml(location => $FILE2);
    for my $branch_node ($customDom->findnodes("/arbre/branche"))
    { $branch_node->setAttribute(type => "resineux"); }
    push(@wanted, $customDom->documentElement->findnodes("./*"));

    my $new = XML::LibXML::Document->new( '1.0', 'UTF-8' );
    $new->addChild($new->createComment("So, in the end we have a fores
+t..."));

    my $root = XML::LibXML::Element->new( 'arbre' );
    $new->addChild( $root );

    $root->addChild( $_ ) for @wanted;

    my $pp = XML::LibXML::PrettyPrint->new(indent_string => "    ");
    $pp->pretty_print($new);

    open(FILE,">$FILEOUT") or die $!; print FILE $new->toString;close 
+FILE;
}

    [download]

    Cheers

[reply]
[d/l]
[select]
      Nop... Nothing to say.
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