Block Hooks: Add apply_block_hooks_to_content_from_post_object

[ockham]

Port of WordPress/gutenberg#68926 and WordPress/gutenberg#69241.

introduc[e] a new function, apply_block_hooks_to_content_from_post_object, to colocate the logic used to temporarily wrap content in a parent block (with ignoredHookedBlocks information fetched from post meta) alongside the call to apply_block_hooks_to_content.

Allow insertion of a hooked block as the first or last child of the Post Content block (and, less importantly, of the Synced Pattern and Navigation blocks).

Fixes #61074, #62716.

Trac ticket: https://core.trac.wordpress.org/ticket/62716

---

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.

[github-actions]

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[Mamaduka]

Adding a unit test for unhappy paths might be a good idea. When post_content returns something different due to the filter.

[Mamaduka]

@ockham, is this ready for review?

[ockham]

@ockham, is this ready for review?

Not quite yet -- I still need to increase test coverage, and audit other callsites of apply_block_hooks_to_content to see if they should be changed to call apply_block_hooks_to_content_from_post_object instead.

I won't be able to work on this PR this week, but I'll continue work next week. I hope that works for you time-wise, @Mamaduka?

[Mamaduka]

Thanks, @ockham!

That timeline should be okay for now. We just need to make sure this is merged before Beta 1.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Core Committers: Use this line as a base for the props when committing in SVN:

Props bernhard-reiter, gziolo, mamaduka.

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[ockham]

Switching back to draft mode since I might've encountered a bug while testing.

Edit: Figured it out, see below.

[ockham]

Note that when testing this with a block theme (e.g. TT5), hooked blocks in the first_child or last_child positions of the Post Content block will be inserted twice. E.g. when using this plugin for testing:

This problem will go away once changes to the Post Content block that were made in WordPress/gutenberg#68926 are synced over to Core.

You can simulate this by applying this patch.

diff --git a/src/wp-includes/blocks/post-content.php b/src/wp-includes/blocks/post-content.php
index e0a06b7217..25be880cc4 100644
--- a/src/wp-includes/blocks/post-content.php
+++ b/src/wp-includes/blocks/post-content.php
@@ -46,33 +46,10 @@ function render_block_core_post_content( $attributes, $content, $block ) {
 		$content .= wp_link_pages( array( 'echo' => 0 ) );
 	}
 
-	$ignored_hooked_blocks = get_post_meta( $post_id, '_wp_ignored_hooked_blocks', true );
-	if ( ! empty( $ignored_hooked_blocks ) ) {
-		$ignored_hooked_blocks  = json_decode( $ignored_hooked_blocks, true );
-		$attributes['metadata'] = array(
-			'ignoredHookedBlocks' => $ignored_hooked_blocks,
-		);
-	}
-
-	// Wrap in Post Content block so the Block Hooks algorithm can insert blocks
-	// that are hooked as first or last child of `core/post-content`.
-	$content = get_comment_delimited_block_content(
-		'core/post-content',
-		$attributes,
-		$content
-	);
-
-	// We need to remove the `core/post-content` block wrapper after the Block Hooks algorithm,
-	// but before `do_blocks` runs, as it would otherwise attempt to render the same block again --
-	// thus recursing infinitely.
-	add_filter( 'the_content', 'remove_serialized_parent_block', 8 );
-
 	/** This filter is documented in wp-includes/post-template.php */
 	$content = apply_filters( 'the_content', str_replace( ']]>', ']]>', $content ) );
 	unset( $seen_ids[ $post_id ] );
 
-	remove_filter( 'the_content', 'remove_serialized_parent_block', 8 );
-
 	if ( empty( $content ) ) {
 		return '';
 	}

[ockham]

Heads-up, I'm thinking to include changes from WordPress/gutenberg#69241 in this. (Should take a couple of minutes only.)

[ockham]

Heads-up, I'm thinking to include changes from WordPress/gutenberg#69241 in this. (Should take a couple of minutes only.)

Done: 970eef5

[gziolo]

I started with reviewing and testing WordPress/gutenberg#69241. In effect, I gained confidence these changes can be safely included here as well. The changes mirror the edits applied in the Gutenberg plugin and they all look good to me.

[github-actions]

A commit was made that fixes the Trac ticket referenced in the description of this pull request.

SVN changeset: 59838
GitHub commit: d455334

This PR will be closed, but please confirm the accuracy of this and reopen if there is more work to be done.