/**
* Returns collection object and assigns statically if not yet set.
*/
public static function getCollection()
{
global $db;
if (!self::$_collection) {
if (!is_a($db, 'MongoDB')) {
trigger_error("DBObjects rely on MongoDB connection", E_USER_ERROR);
}
$classname = get_called_class();
if (!defined($classname . '::collectionName')) {
throw new IncompleteImplementationException("Constant collectionName undefined in {$classname}");
}
self::$_collection = $db->selectCollection(constant($classname . '::collectionName'));
}
return self::$_collection;
}