[wp-trac] [WordPress Trac] #52935: oEmbed cache is no longer refreshed upon post update

[WordPress Trac]

#52935: oEmbed cache is no longer refreshed upon post update
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 Reporter:  david.binda   |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Embeds        |    Version:  5.0
 Severity:  normal        |   Keywords:
  Focuses:                |
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 Before the Block editor was introduced, an AJAX request was used for
 refreshing oEmbed cache of a given post upon it's update.

 See related code:

 https://core.trac.wordpress.org/browser/trunk/src/wp-includes/class-wp-
 embed.php?rev=48586#L81

 and

 https://core.trac.wordpress.org/browser/trunk/src/wp-admin/includes/ajax-
 actions.php?rev=48586#L253

 However, this code is no longer being triggered by the block editor for
 multiple reasons ( post update is happening via REST API, thus there is no
 redirect and the `edit_form_advanced` action prints only hidden fields in
 the block editor ), and even if it were, the `WP_Embed::cache_oembed` does
 not seem to properly parse the Block's editor notation. So, even switching
 to classic editor and updating the post won't make the oEmbeds to refresh.

 The only way to refresh oEmbeds is a WP CLI command ( see
 https://developer.wordpress.org/cli/commands/embed-2/cache/ ).

 Due to the way the Block editor handles display during the editing part
 and it's discrepancy in the front-end displaying part, an embed which, for
 whaterver reason failed to cache ( there is this `{{unknown}}` post meta
 for the URL stored in the database ), the embed may appear working in the
 edit post screen, but would appear broken when rendered on frontend.

 Steps to reproduce / debug the issue would be:
 1. adding a mu-plugin blocking any oEmbeds ( eg.: `add_filter(
 'pre_oembed_result', function() { return false; }, 11 );` ),
 1. create a new post with YouTube oembed
 1. view the post, see it's broken
 1. remove the mu-plugin
 1. open the post in editor, see YouTube working, eventually try to re-save
 the post
 1. view the post on front-end, see it's still broken

 The above steps do not produce broken oEmbed in the last step, when all
 are performed in the classic editor.

 While there is a WP CLI command for refreshing the oEmbed cache, there is
 no longer an easy way for a user w/o access to the server to refresh the
 oEmbed cache (which used to be as easy as re-saving the post).

 Perhaps a cache refreshing logic could be introduced server-side, during
 the post update action?

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Ticket URL: <https://core.trac.wordpress.org/ticket/52935>
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