php SimpleXML check if a child exists

Question

A->b->c might exist but c might not exist. How do I check it?

Answer 1

After some experimentation, I've discovered that the only reliable method of checking if a node exists is using count($xml->someNode).

Here's a test case: https://gist.github.com/Thinkscape/6262156

Answer 2

I use a helper function to check if a node is a valid node provided as a parameter in function.

private static function isValidNode($node) {
  return isset($node) && $node instanceof SimpleXMLElement && !empty($node);
}

Usage example:

public function getIdFromNode($node) {
  if (!self::isValidNode($node)) {
    return 0;
  }
  return (int)$node['id'];
}

Answer 3

Name Spaces

Be aware that if you are using name spaces in your XML file you will need to include those in your function calls when checking for children otherwise it will return ZERO every time:

if ($XMLelement->children($nameSpace,TRUE)->count()){
    //do something here 
}

Answer 4

SimpleXML always return Object. If there is no child, empty object is returned.

if( !empty($a->b)){
  var_dump($a->b);
}

Answer 5

Thought I'd share my experience. Running on 5.4 I tried testing with 'isset' and 'empty' but neither worked for me. I ended up using is_null.

if(!is_null($xml->scheduler->outterList->innerList)) {
    //do something
}

Answer 6

It might be better to wrap this in an isset()

if(isset($A->b->c)) { // c exists

That way if $A or $A->b don't exist... it doesn't blow up.