Question

I am reading a xml file, and I add some additional text, but I can’t get exact text because some special characters automatically converted.

I try this:

<book>
  <book-meta>
    <book-id pub-id-type="doi">1545</book-id>
    <book-title>Regenerating <?tex?> the Curriculum</book-title>
  </book-meta>
</book>

Script:

use strict;

use XML::Twig;

open(my $out, '>', 'Output.xml') or die "can't Create stroy file $!\n";

my $story_file = XML::Twig->new(
    twig_handlers => {
        'book-id'       => sub { $_->set_text('<?sample?>') },
        keep_atts_order => 1,
    },
    pretty_print => 'indented',
);

$story_file->parsefile('sample.xml');
$story_file->print($out);

Output:

<book>
  <book-meta>
    <book-id pub-id-type="doi">&lt;?sample?></book-id>
      <book-title>Regenerating <?tex?> the Curriculum</book-title>
  </book-meta>
</book>

I would like output as:

<book>
      <book-meta>
        <book-id pub-id-type="doi"><?sample?></book-id>
          <book-title>Regenerating <?tex?> the Curriculum</book-title>
      </book-meta>
    </book>

How can I escape this type of character in XML twig. I tried the set_asis option, but I can’t get it to work.

Answer 1

XML::Twig is correctly inserting the string <?sample?> for you as you are asking for a PCDATA node to be added and < must be replaced with < in such a node. However what you want is a processing instruction node.

The easiest way to insert such a node using XML::Twig is using the set_inner_xml method, which will parse an XML tree fragment from a string and insert it as the contents of the current node.

If you replace

$_->set_text('<?sample?>')

with

$_->set_inner_xml('<?sample?>')

then your code should do what you want. The output I get is

<book>
  <book-meta>
    <book-id pub-id-type="doi"><?sample?></book-id>
    <book-title>Regenerating <?tex?> the Curriculum</book-title>
  </book-meta>
</book>