I'm using PHP DOM and I'm trying to get an element within a DOM node that have a given class name. What's the best way to get that sub-element?
Update: I ended up using Mechanize for PHP which was much easier to work with.
Answer
Update: Xpath version of *[@class~='my-class'] css selector
So after my comment below in response to hakre's comment, I got curious and looked into the code behind Zend_Dom_Query. It looks like the above selector is compiled to the following xpath (untested):
[contains(concat(' ', normalize-space(@class), ' '), ' my-class ')]
So the PHP would be:
$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(concat(' ', normalize-space(@class), ' '), ' $classname ')]");
Basically, all we do here is normalize the class attribute so that even a single class is bounded by spaces, and the complete class list is bounded in spaces. Then append the class we are searching for with a space. This way we are effectively looking for and find only instances of my-class .
Use an xpath selector?
$dom = new DomDocument();
$dom->load($filePath);
$finder = new DomXPath($dom);
$classname="my-class";
$nodes = $finder->query("//*[contains(@class, '$classname')]");
If it is only ever one type of element you can replace the * with the particular tagname.
If you need to do a lot of this with very complex selector I would recommend Zend_Dom_Query which supports CSS selector syntax (a la jQuery):
$finder = new Zend_Dom_Query($html);
$classname = 'my-class';
$nodes = $finder->query("*[class~=\"$classname\"]");