Question

I am experiencing a very odd error. I am writing a function to validate XML based on element names, in this case passed in as an array. First, I normalize the input to a SimpleXMLElement object; in this case I am passing in a DOMDocument, and I tested it, it is converting correctly to SimpleXMLElement.

What confuses me is that calling getName() will throw the following:

PHP Fatal error:  Call to a member function getName() on a non-object

But using exit($xml->getName()) (or echo) will return the correct result – the root element name!

Relevant code:

function validateXML($xml, $format='') {
(get_class($xml) !== 'SimpleXMLElement') ?
    ((get_class($xml) === 'DOMDocument') ?
        $xml = simplexml_import_dom($xml)
        : $xml = simplexml_load_string($xml))
    : $xml = $xml;
$rootName = ($xml->getName());
if ($rootName != $format[0]) {
    exit($xml->getName())));
}

Also, in case it matters, the server is running PHP 5.3

I am very new to PHP so help is extremely appreciated!

P.S. To be clear about what exactly is going on, the following code:

function validateXML($xml, $format='') {
    echo(get_class($xml);
    $xml = simplexml_import_dom($xml);
    echo(get_class($xml);
    echo($xml->getName());
}

outputs to the server

DOMDocument
SimpleXMLElement
'ElementName' (the correct root name of my XML document)

… so it appears to be working, except that the fatal error still gets thrown.

Answer 1

Your code (assuming it is close enough to what you have written in the question) will fail when $xml is invalid XML, because simplexml_load_string():

Returns an object of class SimpleXMLElement with properties containing the data held within the xml document, or FALSE on failure.

If you still do not see this, I suggest rewriting your code using if statements instead of tertiary statements. Your function, when $xml is not SimpleXMLElement instance, nor DOMDocument instance, will be effectively coming down to the following function:

function validateXML($xml, $format='') {
    simplexml_load_string($xml);
    $rootName = ($xml->getName());
    if ($rootName != $format[0]) {
        exit($xml->getName());
    };
}