PHP's SimpleXML doesn't save edited data

Question

I'm trying to edit some xml data. After this I want to save the data to file.

The problem is that the edited data isn't saved by simplexml but the node has changed.

$spieler = $xml->xpath("/planer/spieltag[@datum='" .$_GET['date']. "']/spielerliste/spieler");

for ( $i = 1; $i < 13; $i++ ){
    if (!empty($_POST['spieler' .$i ])){
        $spieler[$i-1] = $_POST['spieler' .$i];
    }
}
var_dump($spieler);
$xml->asXML("data.xml");

var_dump() shows the new data, but asXML() doesn't.

Answer 1

Make sure your script has write permission to data.xml

Answer 2

The XPath result array elements aren't PHP ($ref = &$var) references to the actual tree nodes, so this line

    $spieler[$i-1] = $_POST['spieler' .$i];

isn't modifying anything in the tree, you're simply overwriting an entry in a completely independent array.