XPath keeps returning empty node list

Question

I am trying to parse a folder full of .htm files. All these files contain 1 specific element that needs to be removed. It's a td element with class="hide". So far, this is my code. $dir. entry is the full path to the file.

$page = ($dir . $entry);
$this->domDoc->loadHTMLFile($page);
// Use xpath query to find the menu and remove it
$nodeList = $xpath->query('//td[@class="hide"]');

Unfortunately, this is where things already go wrong. If I do a var_dump of the node list, I get the following:

object(DOMNodeList)#5 (0) { }

Just so you folks get an idea of what I'm trying to select, here's an excerpt:

<td width="160" align="left" valign="top" class="hide">
    lots of other TD's and content here
</td>

Does anybody see anything wrong with what I've come up with so far?

Firefox provides Xpath addons which can be useful to double check your paths :) — Martin, Oct 02 '12 at 13:27
Most of the DOM objects cannot be var_dumped, so this is expected. — Gordon, Oct 02 '12 at 13:28
@ZnArK: It's not actually XML, it's HTML I'm parsing. Still, I'll add it to clarify. — Jens Eeckhout, Oct 02 '12 at 14:13
Is your initial file xhtml (i.e. with ``)? If so then your elements will be namespaced and you'll need to set up a prefix mapping using `$xpath->registerNamespace` and use this prefix in the expression e.g. `//xhtml:td` — Ian Roberts, Oct 02 '12 at 14:27
@IanRoberts you're right. That solved it. Can't believe I spent so long trying to figure this out. Thank you. — Jens Eeckhout, Oct 02 '12 at 14:39
Also see http://stackoverflow.com/questions/4776093/why-doesnt-var-dump-work-with-domdocument-objects-while-printdom-savehtml/4776430#4776430 — Gordon, Oct 02 '12 at 15:35

score 6 · Accepted Answer · answered Oct 02 '12 at 15:41

6

Is your initial file xhtml (i.e. with <html xmlns="http://www.w3.org/1999/xhtml">)? If so then your elements will be namespaced and you'll need to set up a prefix mapping using $xpath->registerNamespace and then use this prefix in the expression

$xpath->registerNamespace('xhtml', 'http://www.w3.org/1999/xhtml');
$nodeList = $xpath->query('//xhtml:td[@class="hide"]');

answered Oct 02 '12 at 15:41

Ian Roberts

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this was the issue for me, I actually simply disabled the namespaces entirely while using this library https://github.com/Masterminds/html5-php – Timo Huovinen Aug 14 '15 at 10:20
Same for me (processing PHPUnit Coverage xml) ```php $xml = new DOMDocument; $xml->preserveWhiteSpace = false; $xml->load($coverageIndex); $xml = new DOMXPath($xml); $xml->registerNamespace('phpunit', 'https://schema.phpunit.de/coverage/1.0'); $items = $xml->query('//phpunit:build'); ``` – Adam Mar 30 '23 at 06:41

score 5 · Answer 2 · answered Oct 02 '12 at 13:27

Var dumping an xpath node list object doesn't show anything. Var dump the node list's length.

var_dump($nodeList->length);

If the value is over 0, then you can iterate over it using foreach:

foreach($nodeList as $node)var_dump($node->tagName);

Hope this helps.

For further clarification, here is a full working code snippet:

<?php
$html = <<<END
<html>
    <body>
        <td>

        </td>
        <td class="hide"></td>
        <td class="hide"></td>
    </body>
</html>
END;
$dom = new DOMDocument;
$dom->loadHtml($html);
$xpath = new DOMXpath($dom);
$nodeList = $xpath->query('//td[@class="hide"]');
// Shows a blank object
var_dump($nodeList);
// Shows 2
var_dump($nodeList->length);
// Echo out all the tag names.
foreach($nodeList as $node){
    echo $node->tagName . "\n";
}
?>

You're absolutely right about the var_dump. I've changed that now. I've also checked my code -yet- again, and I see no difference compared to your snippet. Thank you for your reply though. Unfortunately I still get no output (the length of the nodelist returns `int(0)`. — Jens Eeckhout, Oct 02 '12 at 14:17

Bogdan · Answer 3 · 2012-10-02T20:48:58.247

3

Maybe you have more then one class in the class attribute of your td element:

<td class="hide anotherclass">

So '//td[@class="hide"]' would only match:

<td class="hide">

Try it like this to see if it contains the hide class you are looking for:

$nodeList = $xpath->query('//td[contains(@class,"hide")]');

Check out this blog post: XPath: Select element by class

edited Oct 02 '12 at 20:48

answered Oct 02 '12 at 13:28

Bogdan

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Good advice. I double-checked this, but "hide" really is the only class the TD has. Still, thank you, interesting reply. – Jens Eeckhout Oct 02 '12 at 14:16

XPath keeps returning empty node list

3 Answers3