http://www.perlmonks.org?node_id=1004816

techie411 has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to add elements to XML using XML::LibXML. I know how to add elements, but I'm having a hard time trying to go to lower levels of the elements. For instance:

---- ORIGINAL FILE ---- 
<dict>
        <key>TEST1</key>
        <key>TEST2</key>
        <string>en</string>
        <key>TEST3</key>

</dict>

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---- RESULTS I WANT ---- 
<dict>
        <key>ADDKEY</key>
        <array>
              <dict>
                  <key>SAMPLEKEY</key>
                  <array>
                       <string>STRING</string>
                  </array>
              </dict>
        </array>

        <key>TEST1</key>
        <string>en</string>
        <key>TEST2</key>

</dict>

[download]
I'd also like to add it before the TEST1 key. The results I get from below is that it appends it to the end of the 'dict' element.

---- WHAT I HAVE SO FAR ---- 
use strict;
use warnings;

use XML::LibXML;

  # load
  open my $fh, '<', 'test.xml';
  binmode $fh; # drop all PerlIO layers possibly created by a use open
+ pragma
  my $doc = XML::LibXML->load_xml(IO => $fh);
  my $root=$doc->getDocumentElement();

  # Grabs the 'dict' element
  my $rootElement = pop(@{$root>getElementsByTagName('dict')});

my $keyElement= $doc->createElement("key");
$keyElement->appendText('Test');

$rootElement->appendChild($keyElement);

  # save
  open my $out, '>', 'out.xml';
  binmode $out; 
  $doc->toFH($out);

[download]

Replies are listed 'Best First'.
Re: Adding Elements to XML
by Anonymous Monk on Nov 20, 2012 at 23:37 UTC

    SO FAR

    Well, naturally, appendChild adds one to the end, perhaps you want  $root->insertBefore( $newNode, $root->firstChild );

    RESULTS I WANT

    You may not have a choice, but if you do, you should think about WANTing a different xml structure :) for example, one that isn't so recursive -- one where the definitions are children (not siblings) of keys -- its a dictionary :)

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[d/l]
Re: Adding Elements to XML
by choroba (Cardinal) on Nov 21, 2012 at 11:01 UTC
    Using XML::XSH2, a wrapper around XML::LibXML: 
    open 1.xml ;
cd /dict ;
insert element key prepend . ;
set key[1] 'ADDKEY' ;
my $array := insert chunk '<array><dict/></array>' after key[1] ;
my $key   := insert element key into $array/dict ;
insert text 'SAMPLEKEY' into $key ;
my $array2 := insert element array after $key ;
set $array2/string 'STRING' ;

delete key[last()] ;    
xmove :r string[last()] before preceding-sibling::key[1] ;

save :b ;

    [download]
    I tried to demonstrate several ways of creating new nodes: via insert and set (more than one node can be created by both, see insert chunk and setting of string).
    لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ
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[d/l]
[select]
Re: Adding Elements to XML
by Anonymous Monk on Nov 21, 2012 at 12:27 UTC
    Also, generally speaking, use XPath expressions to navigate an XML structure, not hard code. The day will come when you have a structure to deal with that is not-quite what your code was hard-coded to expect. Therefore, as a general approach to this problem, use XPath to find the node(s) you want, then modify them.
[reply]

      have a structure to deal with that is not-quite what your code was hard-coded to expect.

      hardcode an xpath or hardcode something else -- if it changes, your code will change, duh

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