Parse RDF XML file to get all rdf:about values
I am using php's simple xml and xpath to parse an rdf xml file and am struggling to get a list of all the rdf开发者_JAVA百科:about values.
Any advice?
There seems to be an issue when using SimpleXml with namespaced attributes prior to PHP5.3. Basically, anything with a :
will be dropped when converted to an object property of a SimpleXml element. The following will do, but feels hackish to me:
$rdf = str_replace('rdf:about', 'rdf_about', $rdf);
$rdf = new SimpleXMLElement($rdf);
foreach($rdf->xpath('//@rdf_about') as $node) {
echo $node, PHP_EOL;
}
See here:
- http://groups.google.com/group/comp.lang.php/browse_thread/thread/d2a9b29ee21f7403/c6b24b6d398ece2c
You could use DOM instead of SimpleXml:
$dom = new DomDocument;
$dom->loadXml($rdf);
$xph = new DOMXPath($dom);
$xph->registerNamespace('rdf', "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
foreach($xph->query('//@rdf:about') as $attribute) {
echo $attribute->value, PHP_EOL;
}
But, I suggest using a dedicated library for this over SimpleXml or DOM:
- http://arc.semsol.org/docs/v2/parsing
- http://www.seasr.org/wp-content/plugins/meandre/rdfapi-php/doc/
- http://librdf.org/raptor/
- http://phpxmlclasses.sourceforge.net/show_doc.php?class=class_rdf_parser.html
And here's a blog post about the parsers:
- http://www.wasab.dk/morten/blog/archives/2004/05/31/easy-rdf-parsing-with-php
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