PHP Warning in notify_logout method

[hidetaka-dc]

Description:

PHP Warning occurs when attempting to read property "user_login" on a boolean value in the Shifter WordPress MU plugin.

Error Details:

PHP Warning: Attempt to read property "user_login" on bool in /var/www/html/web/wp/mu-plugins/shifter-wp-mu/api/class-shifter-api.php on line 172  

Root Cause:
The issue occurs in the notify_logout method where get_user_by('ID', $user_id) returns false when an invalid user ID is passed, but the code attempts to access the user_login property without checking if the user object is valid.

Steps to Reproduce:

Trigger a WordPress logout event with an invalid or non-existent user ID
The wp_logout hook calls the notify_logout method
get_user_by() returns false for invalid user IDs
Code attempts to access $user->user_login on the boolean false value
Expected Behavior:
The method should handle cases where get_user_by() returns false gracefully without throwing PHP warnings.

Suggested Fix:

Add validation to check if $user is a valid user object before accessing its properties:

public function notify_logout( $user_id ) {  
    $user = get_user_by( 'ID', $user_id );  
    if ( $user && isset( $user->user_login ) ) {  
        $result = $this->call_update_active_user( false, $user->user_login );  
    }  
}

Environment:

Plugin: Shifter WordPress MU shifter.php:15-18
File: api/class-shifter-api.php
Line: 172 (in the notify_logout method)

Notes

This error typically occurs during user session management when invalid user IDs are passed to the logout notification system. The Shifter API's update_active_user functionality tracks active users on WordPress sites and notifies the Shifter platform of login/logout events.

Wiki pages you might want to explore:

Development Workflow (getshifter/shifter-wp-mu)
Coding Standards (getshifter/shifter-wp-mu)