Block Hooks: Apply to Post Content (on frontend and in editor)

backport-changelog/6.8/7898.md

@@ -0,0 +1,3 @@
+https://github.com/WordPress/wordpress-develop/pull/7898
+
+* https://github.com/WordPress/gutenberg/pull/67272

lib/compat/wordpress-6.8/blocks.php

@@ -144,3 +144,165 @@ function gutenberg_stabilize_experimental_block_supports( $args ) {
 }
 
 add_filter( 'register_block_type_args', 'gutenberg_stabilize_experimental_block_supports', PHP_INT_MAX, 1 );
+
+function gutenberg_apply_block_hooks_to_post_content( $content ) {
+	// The `the_content` filter does not provide the post that the content is coming from.
+	// However, we can infer it by calling `get_post()`, which will return the current post
+	// if no post ID is provided.
+	return apply_block_hooks_to_content( $content, get_post(), 'insert_hooked_blocks' );
+}
+// We need to apply this filter before `do_blocks` (which is hooked to `the_content` at priority 9).
+add_filter( 'the_content', 'gutenberg_apply_block_hooks_to_post_content', 8 );
+
+/**
+ * Hooks into the REST API response for the Posts endpoint and adds the first and last inner blocks.
+ *
+ * @since 6.6.0
+ * @since 6.8.0 Support non-`wp_navigation` post types.
+ *
+ * @param WP_REST_Response $response The response object.
+ * @param WP_Post          $post     Post object.
+ * @return WP_REST_Response The response object.
+ */
+function gutenberg_insert_hooked_blocks_into_rest_response( $response, $post ) {
+	if ( empty( $response->data['content']['raw'] ) || empty( $response->data['content']['rendered'] ) ) {
+		return $response;
+	}
+
+	$attributes            = array();
+	$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,
+		);
+	}
+
+	if ( 'wp_navigation' === $post->post_type ) {
+		$wrapper_block_type = 'core/navigation';
+	} else {
+		$wrapper_block_type = 'core/post-content';
+	}
+
+	$content = get_comment_delimited_block_content(
+		$wrapper_block_type,
+		$attributes,
+		$response->data['content']['raw']
+	);
+
+	$content = apply_block_hooks_to_content(
+		$content,
+		$post,
+		'insert_hooked_blocks_and_set_ignored_hooked_blocks_metadata'
+	);
+
+	// Remove mock block wrapper.
+	$content = remove_serialized_parent_block( $content );
+
+	$response->data['content']['raw'] = $content;
+
+	// No need to inject hooked blocks twice.
+	$priority = has_filter( 'the_content', 'apply_block_hooks_to_content' );
+	if ( false !== $priority ) {
+		remove_filter( 'the_content', 'apply_block_hooks_to_content', $priority );
+	}
+
+	/** This filter is documented in wp-includes/post-template.php */
+	$response->data['content']['rendered'] = apply_filters( 'the_content', $content );
+
+	// Add back the filter.
+	if ( false !== $priority ) {
+		add_filter( 'the_content', 'apply_block_hooks_to_content', $priority );
+	}
+
+	return $response;
+}
+add_filter( 'rest_prepare_page', 'gutenberg_insert_hooked_blocks_into_rest_response', 10, 2 );
+add_filter( 'rest_prepare_post', 'gutenberg_insert_hooked_blocks_into_rest_response', 10, 2 );
+
+/**
+ * Updates the wp_postmeta with the list of ignored hooked blocks
+ * where the inner blocks are stored as post content.
+ *
+ * @since 6.6.0
+ * @since 6.8.0 Support non-`wp_navigation` post types.
+ * @access private
+ *
+ * @param stdClass $post Post object.
+ * @return stdClass The updated post object.
+ */
+function gutenberg_update_ignored_hooked_blocks_postmeta( $post ) {
+	/*
+	 * In this scenario the user has likely tried to create a new post object via the REST API.
+	 * In which case we won't have a post ID to work with and store meta against.
+	 */
+	if ( empty( $post->ID ) ) {
+		return $post;
+	}
+
+	/*
+	 * Skip meta generation when consumers intentionally update specific fields
+	 * and omit the content update.
+	 */
+	if ( ! isset( $post->post_content ) ) {
+		return $post;
+	}
+
+	/*
+	 * Skip meta generation if post type is not set.
+	 */
+	if ( ! isset( $post->post_type ) ) {
+		return $post;
+	}
+
+	$attributes = array();
+
+	$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,
+		);
+	}
+
+	if ( 'wp_navigation' === $post->post_type ) {
+		$wrapper_block_type = 'core/navigation';
+	} else {
+		$wrapper_block_type = 'core/post-content';
+	}
+
+	$markup = get_comment_delimited_block_content(
+		$wrapper_block_type,
+		$attributes,
+		$post->post_content
+	);
+
+	$existing_post = get_post( $post->ID );
+	// Merge the existing post object with the updated post object to pass to the block hooks algorithm for context.
+	$context          = (object) array_merge( (array) $existing_post, (array) $post );
+	$context          = new WP_Post( $context ); // Convert to WP_Post object.
+	$serialized_block = apply_block_hooks_to_content( $markup, $context, 'set_ignored_hooked_blocks_metadata' );
+	$root_block       = parse_blocks( $serialized_block )[0];
+
+	$ignored_hooked_blocks = isset( $root_block['attrs']['metadata']['ignoredHookedBlocks'] )
+		? $root_block['attrs']['metadata']['ignoredHookedBlocks']
+		: array();
+
+	if ( ! empty( $ignored_hooked_blocks ) ) {
+		$existing_ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
+		if ( ! empty( $existing_ignored_hooked_blocks ) ) {
+			$existing_ignored_hooked_blocks = json_decode( $existing_ignored_hooked_blocks, true );
+			$ignored_hooked_blocks          = array_unique( array_merge( $ignored_hooked_blocks, $existing_ignored_hooked_blocks ) );
+		}
+
+		if ( ! isset( $post->meta_input ) ) {
+			$post->meta_input = array();
+		}
+		$post->meta_input['_wp_ignored_hooked_blocks'] = json_encode( $ignored_hooked_blocks );
+	}
+
+	$post->post_content = remove_serialized_parent_block( $serialized_block );
+	return $post;
+}
+add_filter( 'rest_pre_insert_page', 'gutenberg_update_ignored_hooked_blocks_postmeta' );
+add_filter( 'rest_pre_insert_post', 'gutenberg_update_ignored_hooked_blocks_postmeta' );

packages/block-library/src/post-content/index.php

@@ -46,10 +46,33 @@ 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 '';
 	}