[% USE docroot = XML.LibXML("helloworld.xml") %]

   The message is: [% docroot.find("/greeting/text") %]

Specifying a Data Source

   # value contains the filename of the xml
   [% USE docroot = XML.LibXML(file => value) %]

   # value contains an open filehandle to some xml
   [% USE docroot = XML.LibXML(fh => value) %]

   # value contains the html string
   [% USE docroot = XML.LibXML(html_string => value) %]

   # value contains the filename of the html
   [% USE docroot = XML.LibXML(html_file => value) %]

   # value contains an open filehandle to some html
   [% USE docroot = XML.LibXML(html_fh => value) %]

Or, if you want you can use similar names to that the XML.XPath plugin uses:

   # value contains the xml string
   [% USE docroot = XML.LibXML(xml => value) %] or
   [% USE docroot = XML.LibXML(text => value) %]

   # value contains the filename of the xml
   [% USE docroot = XML.LibXML(filename => value) %]

   # value contains the html string
   [% USE docroot = XML.LibXML(html => value) %] or
   [% USE docroot = XML.LibXML(html_text => value) %]

   # value contains the filename of the html
   [% USE docroot = XML.LibXML(html_file => value) %]
   [% USE docroot = XML.LibXML(html_filename => value) %]

You can provide extra arguments which will be used to set parser options. See XML::LibXML for details on these. I will repeat the following warning however: ``LibXML options are global (unfortunately this is a limitation of the underlying implementation, not this interface)...Note that even two forked processes will share some of the same options, so be careful out there!''

   # turn off expanding entities
   [% USE docroot = XML.LibXML("file.xml",
                               expand_entities => 0);

Obtaining Parts of an XML Document

  # get the text contained within a node
  [% htmldoc.findvalue("/html/body/h1[1]/text()") %]

Nodes of the xml document can be found with the "findnodes"

  # get all the pages ('pages' is a list of nodes)
  [% pages = docroot.findnodes("/website/section/page") %]

  # get the first page (as TT folds single elements arrays
  # to scalars, 'page1' is the one node that matched)
  [% page1 = docroot.findnodes("/website/section/page[1]") %]

Then further xpath commands can then be applied to those nodes in turn:

  # get the title attribute of the first page
  [% page1.findvalue("@title") %]

An alternative approach is to use individual method calls to move around the tree. So the above could be written:

  # get the text of the h1 node
   [% htmlroot.documentElement
              .getElementsByLocalName("body").first
              .getElementsByLocalName("h1").first
              .textContent %]

  # get the title of the first page
  [% docroot.documentElement
            .getElementsByLocalName("section").first
            .getElementsByLocalName("page").first
            .getAttribute("title") %]

You should use the technique that makes the most since in the particular situation. These approaches can even be mixed:

  # get the first page title
  [% page1 = htmlroot.findnodes("/website/section/page[1]");
     page1.getAttribute("title") %]

Much more information can be found in XML::LibXML::Node.

Rendering XML

or

   The title of the first page is '[%
     docroot.documentElement
            .getElementsByLocalName("section").first
            .getElementsByLocalName("page").first
            .getAttribute("title") %]'

You might want to discard whitespace from text areas. XPath can remove all leading and following whitespace, and condense all multiple spaces in the text to single spaces.

   <p>[% htmlroot.findvalue("normalize-space(
                              /html/body/p[1]/text()
                           )" | html %]</p>

Note that, as above, when we're inserting the values extracted into a XML or HTML document we have to be careful to re-encode the attributes we need to escape with something like the html filter. A slightly more advanced technique is to extract a whole node and use the toString method call on it to convert it to a string of XML. This is most useful when you are extracting an existing chunk of XML en mass, as things like <b> and <i> tags will be passed thought correctly and entities will be encoded suitably (for example '"' will be turned into '&quot;')

  # get the second paragraph and insert it here as XML
  [% htmlroot.findnodes("/html/body/p[2]").toString %]

The most powerful technique is to use a view (as defined by the VIEW keyword) to recursively render out the XML. By loading this plugin "present" methods will be created in the XML::LibXML::Node classes and subclasses. Calling "present" on a node with a VIEW will cause it to be rendered by the view block matching the local name of that node (with any non alphanumeric charecters turned to underscores. So a <author> tag will be rendered by the 'author' block. Text nodes will call the 'text' block with the text of the node.

As the blocks can refer back to both the node it was called with and the view they can choose to recursively render out it's children using the view again. To better facilitate this technique the extra methods "starttag" (recreate a string of the starting tag, including attributes,) "endtag" (recreate a string of the ending tag) and "content" (when called with a view, will render by calling all the children of that node in turn with that view) have been added.

This is probably best shown with a well commented example:

  # create the view
  [% VIEW myview notfound => 'passthru' %]

    # default tag that will recreate the tag 'as is' meaning
    # that unknown tags will 'passed though' by the view
    [% BLOCK passthru; item.starttag;
                       item.content(view);
                       item.endtag;
    END %]

    # convert all sections to headed paragraphs
    [% BLOCK section %]
    <h2>[% item.getAttribute("title") %]</h2>
    <p>[% item.content(view) %]</p>
    [% END %]

    # urls link to themselves
    [% BLOCK url %]
    <a href="[% item.content(view) %]">[% item.content(view) %]</a>
    [% END %]

    # email link to themselves with mailtos
    [% BLOCK email %]
    <a href="mailto:[% item.content(view) %]">[% item.content(view) %]</a>
    [% END %]

    # make pod links bold
    [% BLOCK pod %]
    <b>[% item.content(view) %]</b>
    [% END %]

    # render text, re-encoding the attributes as we go
    [% BLOCK text; item | html; END %]

    # render arrays out
    [% BLOCK list; FOREACH i = item; view.print(i); END ; END %]

  [% END %]

  # use it to render the paragraphs
  [% USE doc = XML.LibXML("mydoc.xml") %]
  <html>
   <head>
    <title>[% doc.findvalue("/doc/page[1]/@title") %]</title>
   </head>
   <body>
    [% sections = doc.findnodes("/doc/page[1]/section");
       FOREACH section = sections %]
    <!-- next section -->
    [% section.present(myview);
       END %]
   </body>
  </html>

Copyright Mark Fowler 2002-3, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

This module wouldn't have been possible without the wonderful work that has been put into the libxml library by the gnome team or the equally wonderful work put in by Matt Sergeant and Christian Glahn in creating XML::LibXML.