I want to use XML::LibXML to process OpenOffice (sxw) files. OpenOffice stores its information in a Zip archive containing several XML files. I have extracted the content.xml file from such an archive.

I have used XML::LibXML before, but never with XML documents that use namespaces. OpenOffice files use various namespaces for the different types of content.

Normally, I would write something like:

my $parser = XML::LibXML->new() or die $!;
my $tree = $parser->parse_file('content.xml') or die $!;
my @nodes = $tree->findnodes('//p');
[download]

to retrieve all the nodes of type p. OpenOffice stores paragraphs in p elements within the text namespace. So, I replaced the findnodes line above with:

my @nodes = $tree->findnodes('//text:p');
[download]

but this returns the error XPath error Undefined namespace prefix in //text:p xmlXPathCompiledEval: evaluation failed.

I fixed this problem with:

my @nodes = $tree->documentElement->findnodes('//text:p');
[download]

but I don't understand why one way works and the other way doesn't. Both contexts (tree and documentElement) work with another XML document that does not use namespaces.

Can anyone here enlighten me?

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