Using PHP to get DOM Element

Question

I'm struggling big time understanding how to use the DOMElement object in PHP. I found this code, but I'm not really sure it's applicable to me:

$dom = new DOMDocument();
$dom->loadHTML("index.php");

$div = $dom->getElementsByTagName('div');
foreach ($div->attributes as $attr) {
     $name = $attr->nodeName;
     $value = $attr->nodeValue;
     echo "Attribute '$name' :: '$value'<br />";
}

Basically what I need is to search the DOM for an element with a particular id, after which point I need to extract a non-standard attribute (i.e. one that I made up and put on with JS) so I can see the value of that. The reason is I need one piece from the $_GET and one piece that is in the HTML based from a redirect. If someone could just explain how I use DOMDocument for this purpose, that would be helpful. I'm really struggling understanding what's going on and how to properly implement it, because I clearly am not doing it right.

EDIT (Where I'm at based on comment):

This is my code lines 4-26 for reference:

<div id="column_profile">
    <?php
        require_once($_SERVER["DOCUMENT_ROOT"] . "/peripheral/profile.php");            
        $searchResults = isset($_GET["s"]) ? performSearch($_GET["s"]) : "";

        $dom = new DOMDocument();
        $dom->load("index.php");

        $divs = $dom->getElementsByTagName('div');
        foreach ($divs as $div) {
            foreach ($div->attributes as $attr) {
              $name = $attr->nodeName;
              $value = $attr->nodeValue;
              echo "Attribute '$name' :: '$value'<br />";
            }
        }
        $div = $dom->getElementById('currentLocation');
        $attr = $div->getAttribute('srckey');   
        echo "<h1>{$attr}</a>";
    ?>
</div>

<div id="column_main">

Here is the error message I'm getting:

Warning: DOMDocument::load() [domdocument.load]: Extra content at the end of the document in ../public_html/index.php, line: 26 in ../public_html/index.php on line 10

Fatal error: Call to a member function getAttribute() on a non-object in ../public_html/index.php on line 21

Answer 1

getElementsByTagName returns you a list of elements, so first you need to loop through the elements, then through their attributes.

$divs = $dom->getElementsByTagName('div');
foreach ($divs as $div) {
    foreach ($div->attributes as $attr) {
      $name = $attr->nodeName;
      $value = $attr->nodeValue;
      echo "Attribute '$name' :: '$value'<br />";
    }
}

In your case, you said you needed a specific ID. Those are supposed to be unique, so to do that, you can use (note getElementById might not work unless you call $dom->validate() first):

$div = $dom->getElementById('divID');

Then to get your attribute:

$attr = $div->getAttribute('customAttr');

EDIT: $dom->loadHTML just reads the contents of the file, it doesn't execute them. index.php won't be ran this way. You might have to do something like:

$dom->loadHTML(file_get_contents('http://localhost/index.php'))