Question

I am trying to process a XML with XML::LibXML and report lines where certain elements are. According to docs linked above, line_numbers option should do the trick, but I keep getting 0. The code:

use XML::LibXML;

my $parser = XML::LibXML->new({ line_numbers => 1 });
my $xml = $parser->load_xml(location => 'some.xml');

for my $node ($xml->findnodes('//function')) {
    warn $node->nodePath,"\n";
    warn $node->line_number,"\n";
}

The node is found, my output is

/database/functions/function
0

Any idea how to get it working?

Answer 1

From the documentation:

---

$lineno = $node->line_number();

This function returns the line number where the tag was found during
parsing. If a node is added to the document the line number is 0.
Problems may occur, if a node from one document is passed to another
one.

If the line_numbers flag of the parser was not activated before
parsing, line_number() will always return 0.

---

Was the node added during the course of the XML manipulation?

---

It wasn’t. A closer investigation showed that the offending function was the load_xml. Replace it with the following and it works fine:

my $xml = $parser->parse_file('some.xml');