Perl: Changing html element Label by ID - html

Question

How does one with perl change an html element's value using the html element's ID. How do you do this in the code.
For example:
<div id="container">
<form id="form" action="../code.cgi" method="post">
<label id="lblMessage" class="text">Message</label>
</form>
</div>
How would I change the label's text in my perl script?

Answer 1

Get an HTML or XML parser find the element (e.g., by XPath expression), and remove all its child text nodes, and add a new text node with the text you want.
use strict;
use warnings;
use XML::LibXML;
my $dom = XML::LibXML->load_html(location => 'myfile.html');
my $xpath = XML::LibXML::XPathContext->new($dom);
foreach my $label ($xpath->findnodes('//label[#id="lblMessage"]')) {
$label->removeChildNodes();
$label->addChild($dom->createTextNode("new text"));
}
Caveat: if there are other nodes (elements, like <b> or <span>) in your label, these get removed as well.
You probably need to add some code to write the modified html back to a file.

Answer 2

I, personally like HTML::TreeBuilder for this sort of task.
use HTML::TreeBuilder;
my $html = <<END;
<div id="container">
<form id="form" action="../code.cgi" method="post">
<label id="lblMessage" class="text">Message</label>
</form>
</div>
END
my $root = HTML::TreeBuilder->new_from_content( $html );
$root->elementify(); # Become a tree of HTML::Element objects.
my $message = $root->find_by_attribute( 'id', 'lblMessage' )
or die "No such element";
$message->delete_content();
$message->push_content('I am new stuff');
print $root->as_HTML();