Can I use an xpath query on a result already obtained using xpath?
Add a comment
|
3 Answers
In most hosting languages/environments (like XSLT, XQuery, DOM) you can. Don't know about PHP, but it would be strange if it doesn't allow this.
Of course, the result of the first query must be a node-set, in order for a future "/" operator to be possible/allowed/successful on it.
answered Apr 9, 2010 at 18:07
Dimitre Novatchev
244k27 gold badges307 silver badges438 bronze badges
Comments
I have done it in PHP/SimpleXML. The thing that I didn't understand at first is that you're still dealing with the full SimpleXML object, so if you start with "/nodename", you're operating on root. If you start with "nodename" you are starting at the beginning of the result node. Here's my example:
$parsed=simplexml_load_string($XML);
$s = '/ItemSearchResponse/Items/Item';
$items = $parsed->xpath($s);
foreach($items as $item)
{
$s = 'ItemAttributes/Feature';
$features[]=$item->xpath($s);
$s = 'ASIN';
$asins[]=$item->xpath($s);
$s = 'ImageSets/ImageSet[@Category="primary"]';
$primary_img_set=$item->xpath($s);
$s = 'MediumImage/URL';
$medium_image_url[] = $primary_img_set[0]->xpath($s);
}
Comments
In PHP, for example, you can run a query with a context, i.e. a given node. So if you have got a DOMNodeList as a result of the first query you can do things like this:
$query1 = '//p';
$query2 = './a'; // do not forget the dot
$node = $xpath->query($query1)->item(0);
$result = $xpath->query($query2, $node);
Of course this is a silly example because it could have been done just in one shot with the correct XPath experssion but I believe it illustrates your question.
