I use my own custom function...
public function areNull() {
if (func_num_args() == 0) return false;
$arguments = func_get_args();
foreach ($arguments as $argument):
if (is_null($argument)) return true;
endforeach;
return false;
}
$var = areNull("username", "password", "etc");
I'm sure it can easily be changed for you scenario. Basically it returns true if any of the values are NULL, so you could change it to empty or whatever.