Implement a more reliable way to retrieve the current post to avoid conflicts when a plugin resets the $post variable

[designsimply]

Moved from #7461 (and quoting @aduth) 🙂 to make the underlying issue smaller and clearer:

Here are steps to reproduce from a fresh install:

1. Install Strong Testimonials plugin
2. Publish a new Testimonial via Testimonials > Add New
3. Create and save a new Testimonial view via Testimonials > Views > Add New
4. Copy the generated view shortcode
5. Paste shortcode into a new post via Posts > Add New
6. Save post
7. Refresh page

Specifically, Strong Testimonials is causing the $post global to be overridden via its shortcode template rendering.

Working backwards:

1. https://github.com/WordPress/wordpress-develop/blob/0e7ed499e0c9f2f5df3c26b982b9722fe83af906/src/wp-includes/class-wp-query.php#L3229
2. https://github.com/cdillon/strong-testimonials/blob/3d07e4fb47af06a1d04207a8cb76fc3f1fb51840/templates/default/content.php#L15
3. https://github.com/cdillon/strong-testimonials/blob/3d07e4fb47af06a1d04207a8cb76fc3f1fb51840/includes/class-strong-view-display.php#L163
4. https://github.com/cdillon/strong-testimonials/blob/3d07e4fb47af06a1d04207a8cb76fc3f1fb51840/includes/class-strong-testimonials-shortcode.php#L95
5. https://github.com/cdillon/strong-testimonials/blob/3d07e4fb47af06a1d04207a8cb76fc3f1fb51840/includes/class-strong-testimonials-shortcode.php#L16

While the rendered preview is not used, it's still being generated due to the default behavior of the posts REST API endpoint (i.e. post.content.rendered).

Since there's a good chance that more than just this one plugin could cause the $post variable to be reset, I think it might be in our interest to implement a more reliable way to retrieve the current post.

A few ideas:

• Recreate assignment as done in wp-admin/post.php
• Assign a Gutenberg-specific global variable using the $post value passed through the replace_editor filter

Separately, I have opened a pull request to the Strong Testimonials repository at WPChill/strong-testimonials#12 to avoid overriding the $post variable. You can copy the modifications into your own copy of the plugin and it should resolve the issue.

[cdillon]

Please help me understand. You found something that's not working in Gutenberg and that is related to a known bug in WordPress admin and you want me to update my plugin to be compatible? Am I reading this correctly?

[aduth]

@cdillon There are a few things going on here.

The existence of the core bug means that your plugin's calling of the_post in the shortcode rendering will result in the $post global being overridden. I expect this is not done intentionally. Any core logic or plugin which relies on the global (such as Gutenberg) may encounter issues such as those demonstrated in #7461.

Regardless of whether you decide to make any changes to your plugin, Gutenberg should be updated to be more resilient to this, likely by not using $post, which by the existence of this core bug is shown to be too fragile and easily changed to rely upon.

This presumably becomes a non-issue if Core Trac#18408 is resolved.

[danielbachhuber]

This was at least partially addressed by #7889 The longer term fix will need to be https://core.trac.wordpress.org/ticket/18408