How to fix the __PHP_Incomplete_Class Object error in PHP $_SESSION’s

I ran into a problem recently where I was instantiating an object and passing it login credentials in order to authenticate a user. If the users email address and password were correct my method will return me an object containing all of an individual users information that’s important to their $_SESSION so it can persist across pages, as you normally want in an authenticated system.

Note: I have not tested this with normal arrays. I have only tested this with the $_SESSION superglobal array.

The __PHP_Incomplete_Class Error

If you initialize a session (session_start) before you have instantiated the object and then you assign the object to a $_SESSION variable then you print_r($_SESSION) you will receive this error.

__PHP_Incomplete_Class Object (
[__PHP_Incomplete_Class_Name] => user
[user] => __PHP_Incomplete_Class Object (
…
No bueno
…
)

Here’s a code example

session_start();
$user = user::authenticate($email, $password);

if ($user !== false) {
$_SESSION['user'] = $user;
}

// __PHP_Incomplete_Class
print_r($_SESSION['user']);

This will give you a similar error to the example provided above. Don’t ask me why.  I haven’t gone balls deep (forgive the crude analogy) in the parser code to analyze the origination of this issue, I just know how to fix it.

Fix the __PHP_Incomplete_Class Error

If you instantiate the object before you initialize the session then you’re golden.  Take this code in its for instance:

$user = user::authenticate($email, $password);

if ($user !== false) {
session_start();

$_SESSION['user'] = serialize($user);
}

// Fixed!
print_r($_SESSION);

P.S. You  want to turn  session.auto_start OFF in the php.ini
If you don’t know how to do this make sure in your php.ini that session.auto_start = Off.

That’s basically it. If you have any questions, feel free to post in the comments section.

Your welcome,
bryan