Question

Can anyone help explain to me why the following is returning duplicate data?

<?php
$xml_test = '<array key="results">
    <array key="123">
        <string key="mask">1234</string>
    </array>
    <array key="987">
        <string key="mask">5678</string>
    </array>
</array>';

$load_test = simplexml_load_string($xml_test);

foreach ($load_test as $array)
{
    $mask = $array->xpath('//string[@key="mask"]');

    print 'Mask: ' . $mask[0] . '<br />';
}

Returns:

Mask: 1234
Mask: 1234

If I throw a print_r($array) within the foreach loop, I get:

SimpleXMLElement Object
(
    [@attributes] => Array
        (
            [key] => 123
        )

    [string] => 1234
)
Mask: 1234

SimpleXMLElement Object
(
    [@attributes] => Array
        (
            [key] => 987
        )

    [string] => 5678
)
Mask: 1234

What the hell is going on? Why am I getting duplicate masks when I use an xPath expression when both of the $array quite clearly are not holding duplicate data.

Answer 1

Starting the location path in xpath() with / makes it “absolute”, whereas you want to query “relative” to the $array element. For your example, just take out the //.

foreach ($load_test as $array)
{
    $mask = $array->xpath('string[@key="mask"]');

    print 'Mask: ' . $mask[0] . '<br />';
}

See also http://www.sitepoint.com/forums/showthread.php?723058-php-xml-loop&p=4778177&viewfull=1#post4778177