transition_post_status hook always return the same status value for $old_status and $new_status arguments.

[avillegasn]

Describe the bug
The action transition_post_status is fired when you change the status of a post. It has three parameters according to the documentation:

• $new_status (string): New post status.
• $old_status (string): Old post status.
• $post (WP_Post): Post object.

In the classic editor, the hook worked fine. In Gutenberg (block editor) the hook fires properly but the values of $new_status and $old_status are always the same. When you have a draft and save it as pending, the hook is called with both $old_status and $new_status to 'pending'. The same happens all the time when you change the status of a post.

To Reproduce
Steps to reproduce the behavior:

1. Hook into transition_post_status. Something like the following code in functions.php will do the job:

add_action( 'transition_post_status', 'log_data', 10, 3 );
function log_data( $new_status, $old_status, $post ) {
   error_log( 'From ' . $old_status . ' to ' . $new_status . ' for post ' . $post->ID );
}

2. Change the status of a post in the new block editor.
3. Check the error log and you'll see the same value for $new_status and $old_status.

Expected behavior
$old_status should take the proper value instead of always returning the same value as $new_status.

[TimothyBJacobs]

I haven't been able to replicate this. I see proper transitions from draft to pending and pending back to draft. Do you have any classic meta boxes in the Block Editor?

[avillegasn]

Yes, I have. Now that's weird @TimothyBJacobs. When I put the code in functions.php and deactivate the plugins that add the classic meta boxes, everything works fine.

But when I activate the plugin that hooks to transition_post_status, the log from the functions.php works fine but the log in that plugin shows the same value for both new and old status.

The code in the theme is linked directly to transition_post_status (as in the example) while the hook in the plugin is linked to transition_post_status inside a function that is executed in the hook plugins_loaded. Not sure if that may be the problem, but that worked before in the Classic Editor. I'm confused.

[TimothyBJacobs]

And the error log is entirely of the same status to same status? No entries that are correct?

[avillegasn]

The entries that are correct are those from the code in functions.php. The entries from the plugin are entirely of the same status to same status. Both codes are the same, but the code in the theme works while the code in the plugin don't.

I got the following after transitioning from draft to post in the error log:

[11-Dec-2018 16:11:32 UTC] THEME: From draft to pending for post 281
[11-Dec-2018 16:11:32 UTC] PLUGIN: From pending to pending for post 281
[11-Dec-2018 16:11:32 UTC] THEME: From pending to pending for post 281

[avillegasn]

@TimothyBJacobs apparently I found the problem. The hook in the plugin is only done when is_admin(). It seems that is_admin() is not set to true in Gutenberg REST API requests, and that's why the hook was not working as expected.

According to #11138, @swissspidy indicated "Since Gutenberg uses the REST API to save posts, you would have to check for that, not is_admin or wp_doing_ajax". What substitutes is_admin() in this case is not clear to me. Is there an is_rest() method? I tried checking REST_REQUEST as indicated here but didn't work.

In some cases (like transition_post_status) I just want to hook when is_admin() or "is_rest" to avoid adding more load in the front end. Any clues? Thanks!

[swissspidy]

Yeah the REST_REQUEST constant can be used for that, e.g. by checking for defined( 'REST_REQUEST' ) && REST_REQUEST.

I don't see the need for that though. transition_post_status is likely never to be called on the front end, and hooking into an action that's never called has basically no impact on performance. So to me that sounds like you make it more complicated than it needs to be :-)

[avillegasn]

Thanks for the comment @swissspidy. That's true, we where doing things more complicated than they should be. I've reorganized the hooks to avoid problems like this one. The issue is now closed :-)

[niklaz]

Hi,
I can confirm that when using transition_post_status, for new posts that get published it has only:
'new_to_auto-draft' and 'publish_to_publish'