Question

It’s like this:

$var = $obj->data->field;

echo $var; // works, I get the value of 'field'

if(empty($var)) echo '$var is empty!'; // I get this message too. wtf?

What’s the problem here? Why does empty() return true?

Answer 1

My guess: $obj->data->field “is” an object and the class does not implement the __isset() method as you’d need it in order to use empty() this way.

What does

echo "type:", gettype($obj->data), " class:", get_class($obj->data);

print?

---

self-contained example to demonstrate the effect:

<?php
class Bar {
    public $flag=false;
    public function __isset($key) {
        return $this->flag;
    }

    public function __get($key) {
        return '#'.$key.'#';
    }
}

$foo = new StdClass;
$foo->bar = new Bar;
echo empty($foo->bar->test) ? 'empty':'not empty', ", ", $foo->bar->test, "\n";

$foo->bar->flag = true;
echo empty($foo->bar->test) ? 'empty':'not empty', ", ", $foo->bar->test, "\n";

prints

empty, #test#
not empty, #test#