Warning from pluck function on some random pages

[gautammkgarg]

While using WordPress 7.0-beta2, I was getting warnings on some random WordPress admin pages. I made a minor change to fix it and raised the PR.

PHP Warning:  Undefined property: stdClass::$plugin in \wp-includes\class-wp-list-util.php on line 168

Pull Request: ​https://github.com/WordPress/WordPress/pull/784

Add property_exists check before accessing field.
Fixed warning in PHP.

PHP Warning:  Undefined property: stdClass::$plugin in \wp-includes\class-wp-list-util.php on line 168

Trac ticket: https://core.trac.wordpress.org/ticket/64775

[mukesh27]

Hi there! Welcome to Trac 👋

Thanks for the ticket and the PR, much appreciated!

Could you please add unit tests that verify the expected behavior? It would also be helpful to include clear testing instructions in the ticket description so others can easily reproduce and validate the issue.

That will make the review process much smoother. Thanks again!

[westonruter]

Nevertheless, how would a developer discover that they are requesting an invalid key for the array of objects/arrays? What underlying code was attempting to pluck the plugin property?

[siliconforks]

See also: #59774

[westonruter]

Duplicate of #59774.

Thanks for that. Closing as duplicate.

[siliconforks]

Replying to westonruter:

Duplicate of #59774.

Thanks for that. Closing as duplicate.

I'm not sure I would call this a duplicate... I wouldn't recommend trying to change the pluck() function (because it was tried before and it caused regressions), but shouldn't we still try to figure out what code is looking for the plugin property and triggering the warning (like you said in this comment above)?

@gautammkgarg - can you describe the exact steps needed to reproduce these warnings? Which admin pages are you seeing these warnings on?

[gautammkgarg]

I was getting this warning on some random pages. Today I tried to replicate the issue again but today I am not getting the warnings. I don't remember on what pages I was getting the error. But what I do remember is that $value of below code was having data of few plugins, One of them was Angelleye Updater: ​https://github.com/angelleye/angelleye-updater, if I remember is correctly.

					$newlist[ $key ] = $value->$field;

As I am not getting this error everytime, so I am assuming that it might be triggered from some scheduler.

Replying to siliconforks:

@gautammkgarg - can you describe the exact steps needed to reproduce these warnings? Which admin pages are you seeing these warnings on?

[gautammkgarg]

Exception in Visual Studio Code

[gautammkgarg]

Hello @siliconforks, @westonruter and @mukesh27

I again got the same warning. This time I have saved more information that might help you further in debugging.

I am getting this error on "Add Plugin" page ie "/wp-admin/plugin-install.php"

I have the full stack trace with me, but WordPress is not allowing me to submit it here. If you need it, please tell me the steps to provide the full stack trace.

During the warning, value of the $value was

class stdClass { public $slug = 'angelleye-updater'; public $upgrade = FALSE }

and the value of $field was "plugin"

I also tried deactivating and activating the 'angelleye-updater' plugin after I see this warning. After reactivation the error go away.

Kindly refer attached screenshots.

[siliconforks]

I was able to reproduce this with the following steps:

1. Install the Angell EYE Updater plugin by cloning the repository at ​https://github.com/angelleye/angelleye-updater

2. Activate the plugin

3. You might need WP_DEBUG set to true in your wp-config.php file

4. Go to Dashboard → Updates. (This should trigger a check for updates, which is necessary to reproduce the issue.)

5. Go to Plugins → Add Plugin.

If it doesn't work it may be because WordPress will not check for updates more often than once every minute. Simply wait for at least 1 minute and then repeat steps 4 and 5 again.

It looks like this issue is specific to the Angell EYE Updater plugin. It adds a pre_set_site_transient_update_plugins filter to modify the update_plugins transient, and when it does this it creates an object which has only a slug property (and therefore it has no plugin property, so you end up getting the warning Undefined property: stdClass::$plugin):

​https://github.com/angelleye/angelleye-updater/blob/v2.0.22/includes/class-angelleye-updater-update-checker.php#L135-L137

[gautammkgarg]

Thanks @siliconforks for investigating this issue further and providing more detailed steps to replicate the issue.

Replying to siliconforks:

It looks like this issue is specific to the Angell EYE Updater plugin. It adds a pre_set_site_transient_update_plugins filter to modify the update_plugins transient, and when it does this it creates an object which has only a slug property (and therefore it has no plugin property, so you end up getting the warning Undefined property: stdClass::$plugin):

Good observation. It looks like the issue is due to wrong code of "Angell Eye Update" plugin because most of the plugins are not triggering this warning.

It's not under WordPress' control how developers write the code for their plugins or theme. But the warning which we get in the logs or screen is making user confused. With the error message, it's difficult to understand if the issue is at WordPress' end or at Plugin's/Theme's end.

We can trigger the warning even by executing this code

wp_list_pluck([
        (object)[]
], 'any_key');

Looks like the other similar ticket (https://core.trac.wordpress.org/ticket/59774) is currently on paused status.

In my opinion, the suggestions by @westonruter should be merged, as this will handle the warning without impacting the existing functionality.

1. ​https://github.com/WordPress/wordpress-develop/pull/11115/changes/91716f77cb3226721f508341c7cf6ab949e98d80

2. ​https://github.com/WordPress/wordpress-develop/pull/11115/changes/31a638613ca0cc79ff9beb674cc9130969d7f193