Add revisioning of post meta, including ‘footnotes’ by default

[adamsilverstein]

Trac ticket: https://core.trac.wordpress.org/ticket/20564

Related Gutenberg Ticket: WordPress/gutenberg#52988

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This Pull Request is for code review only. Please keep all other discussion in the Trac ticket. Do not merge this Pull Request. See GitHub Pull Requests for Code Review in the Core Handbook for more details.

[adamsilverstein]

See WordPress/gutenberg#52686

[Mamaduka]

@adamsilverstein, should we try using register_meta for enabling post meta revisions instead of wp_post_revision_meta_keys filter?

[adamsilverstein]

@adamsilverstein, should we try using register_meta for enabling post meta revisions instead of wp_post_revision_meta_keys filter?

Sure, good idea - I'll give it a try

[spacedmonkey]

Pinging @swissspidy as this change may effect the web stories plugin that has a custom revision / autosave endpoint.

[spacedmonkey]

I tested this with the web stories plugin that has many custom post types and meta. Seems to work well. Just some little bits of feedback and we should be nearly ready to commit.

[adamsilverstein]

@spacedmonkey thinking we should check for 0 here as well since _wp_put_post_revision can return 0.

[spacedmonkey]

How about this?

if( 0 === $revision_id ) {
    return new WP_Error(...
}

[adamsilverstein]

$revision_id could be 0 OR a wp_error here so I think we need to check for both which is what I did.

[spacedmonkey]

Do we need to update wp_create_initial_post_meta?

[adamsilverstein]

Do we need to update wp_create_initial_post_meta?

Not sure, I'm going to get this committed then we can revisit during beta.

[spacedmonkey]

Suggested change

	// Restore any revisioned meta fields.
	wp_restore_post_revision_meta( $post_id, $revision['ID'] );

@adamsilverstein This is not need anymore, as it hooked in the next line.

[adamsilverstein]

👍🏼 will commit in a follow up

[spacedmonkey]

Good to commit. We will follow up with any issues.

[adamsilverstein]

Fixed in https://core.trac.wordpress.org/changeset/56714