Notice with clean_user_cache when deleting a user

[blueyed]

I just got the following error when deleting a user in a network setup site / multisite setup:

Notice: Trying to get property of non-object in /srv/wordpress/wp-includes/user.php on line 1152
Call Stack:
    0.0000     342776   1. {main}() /srv/wordpress/wp-admin/network/users.php:0
    0.1137    3522036   2. wpmu_delete_user() /srv/wordpress/wp-admin/network/users.php:201
    0.1278    3528060   3. clean_user_cache() /srv/wordpress/wp-admin/includes/ms.php:165

This can happen when $user = WP_User::get_data_by( 'id', $id ); is "false".

The patch appears to be trivial, so I am attaching it inline:

diff --git i/wp-includes/user.php w/wp-includes/user.php
index 463f311..8d99dd5 100644
--- i/wp-includes/user.php
+++ w/wp-includes/user.php
@@ -1149,9 +1149,11 @@ function clean_user_cache($id) {
        $user = WP_User::get_data_by( 'id', $id );
 
        wp_cache_delete($id, 'users');
-       wp_cache_delete($user->user_login, 'userlogins');
-       wp_cache_delete($user->user_email, 'useremail');
-       wp_cache_delete($user->user_nicename, 'userslugs');
+       if ( is_object($user) ) {
+               wp_cache_delete($user->user_login, 'userlogins');
+               wp_cache_delete($user->user_email, 'useremail');
+               wp_cache_delete($user->user_nicename, 'userslugs');
+       }
 }
 
 /**

Apart from that I suggest the following documentation fix:

diff --git i/wp-includes/capabilities.php w/wp-includes/capabilities.php
index 19568e5..481edd8 100644
--- i/wp-includes/capabilities.php
+++ w/wp-includes/capabilities.php
@@ -482,7 +482,7 @@ class WP_User {
         *
         * @param string $field The field to query against: 'id', 'slug', 'email' or 'login'
         * @param string|int $value The field value
-        * @return object Raw user object
+        * @return object|boolean Raw user object, false on error.
         */
        static function get_data_by( $field, $value ) {
                global $wpdb;

I am using WP trunk (via the Github mirror).

[duck_]

The problem with the patch is that it could leave old data in the cache.

Previously noticed by jjj on #19500 with a patch provided. Though I'm tempted to leave this ticket open as it is a separate issue really.

Similar issue with post caches at the end of #19690.

[ryan]

Looks good.

[duck_]

In [20522]:

Pass full user objects to clean_user_cache(). See #19500, fixes #20460.

Prevents notices when clean_user_cache() is called for a user that has been removed from the database.

[duck_]

In [20523]:

clean_user_cache() after the DELETE query in wp_delete_user(). See #20460.

This is to prevent plugins managing to hook in between the cache cleaning and the actual deletion.

[duck_]

In [20532]:

Don't deprecate cleaning the user cache by ID. See #20460.

[blueyed]

This code should take into account that WP_User->get_data_by might return false.
This would lead to a fatal error then with $user->exists() (where $user is a non-object).

[duck_]

Replying to blueyed:

This code should take into account that WP_User->get_data_by might return false.
This would lead to a fatal error then with $user->exists() (where $user is a non-object).

The WP_User::get_data_by() method is not used directly anymore. It was replaced with "new WP_User()" which will always return a WP_User object.