empty() returns wrong result

Question

$user = new User(1);

var_dump($user->ID);
if (empty($user->ID))
    echo "empty";

// output string(2) "77" empty

So why is empty() returning true even when $user var is not empty?

The relevant parts of my User class:

class User {
    protected $data = null;

    public function __construct($userID) {
        // sql select
        $this->data = $sqlResult;
    }

    // ...

    public function __get($name) {
        if (isset($this->data[$name]))
            return $this->data[$name];
        else
            return null;
    }

}

UPDATE:

So I updated my User class and added the __isset() method

public function __isset($name) {
        if (isset($this->data[$name]) && !empty($this->data[$name]))
                return true;
        else
                return false;
}

This leads me to another problem: When calling empty() on my not empty var empty($user->ID) it will return false, but when using isset($user->ID) on a declared var which is empty (e.g. $user->ID = '') it will also return false, because isset() will call __isset() inside the class, right?

Is there a way to fix this behaviour? PHP notes, that I should copy the overloaded property into a local variable, which seems too much paperwork for me ;)

The answer is here: http://stackoverflow.com/questions/6241039/php-empty-doesnt-work-with-a-getter-method — graup, Apr 04 '13 at 14:23
it is evaluating to see if `ID` exists in the `User` class. It is case sensitive — karthikr, Apr 04 '13 at 14:23

score 9 · Accepted Answer · edited Jan 24 '14 at 21:42

9

empty() doesn't call __get(). You need to implement __isset().

edited Jan 24 '14 at 21:42

Eran

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answered Apr 04 '13 at 14:24

Rob

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Good answer! You should consider to give a short example. Just for future reference. – hek2mgl Apr 04 '13 at 14:25
Updated my answer, please check it one more time! Thanks! – Chris Apr 04 '13 at 14:49

score 2 · Answer 2 · edited Jun 20 '20 at 09:12

2

Quoting from the manual:

Note:

It is not possible to use overloaded properties in other language constructs than isset(). This means if empty() is called on an overloaded property, the overloaded method is not called.

edited Jun 20 '20 at 09:12

Community

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answered Apr 04 '13 at 14:25

Mark Baker

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Updated my answer, please check it one more time! Thanks! – Chris Apr 04 '13 at 14:49

score 2 · Answer 3 · answered Apr 04 '13 at 14:29

2

According to the docs, you should overload __isset() for empty to work

answered Apr 04 '13 at 14:29

Steve Lazaridis

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Updated my answer, please check it one more time! Thanks! – Chris Apr 04 '13 at 14:50

empty() returns wrong result

3 Answers3