http://qs321.pair.com?node_id=742458

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

I am rather new to the world of Perl, and I was wondering if anyone had some advice/experience using XPath and libXML.

I am trying to comb through an XML style document and replace some of the data. So far I have only been partially successful, and I have also generated some questions that I have not been able to answer:

How can I access an attribute of the root node?
"Regular" XPath uses . and @ characters which have different uses in Perl, is there some workaround for using these in libXML?
I found a script using "/text()", which is a valid means to access the value of an element. Are there other similar/related calls I can use?

Pretty much, it looks like I am missing the basic syntax for XPath in libXML. Any help with this is appreciated.

Thanks.

Replies are listed 'Best First'.
Re: Using XPath in libXML
by Corion (Patriarch) on Feb 09, 2009 at 15:29 UTC

    You don't show us your code, you don't show us your data, and you don't show us the error message you get. My crytal ball claims that maybe you're just running double quoted strings where you should be using single quoted strings. See perlop about how these differ - one interpolates and the other doesn't.

    For the record, I had no problems using the XPath implementation of XML::LibXML. Accessing an attribute of a root node (or rather, getting the node containing it) would be done using

    /root@foo

    [download]

    as the XPath expression. A likely sample could be:

    ...
my $query = '/root@foo';
my @nodes = $document->find_nodes($query);

    [download]
[reply]
[d/l]
[select]
      Ah, the quotes mix up. I didn't consider that. The criteria I was using to access some of the nodes was in the form: 

      my $query  = "//property[color = 'Blue']/OtherProperty/text()";

      [download]

      This threw me off. I switched to using the single (literal) quotes and this has helped quite a bit. However I am still curious if there are other "/text()" style path calls. (Just in case there are better ways of doing things.)

      Thanks for you help.
[reply]
[d/l]

Back to Seekers of Perl Wisdom