Block Hooks: Allow child insertion into Template Part block.

The Block Hooks mechanism was previously extended to allow insertion of a block as a Navigation block's first or last child. This was implemented by storing the `ignoredHookedBlocks` array in the corresponding `wp_navigation` post's post meta (instead of a metadata attribute on the anchor block).

This changeset extends that mechanism to Template Part blocks, by storing said metadata in the corresponding `wp_template_part` post's post meta, thus allowing extenders to use Block Hooks to insert a block as a Template Part block's first or last child, respectively.

Props tomjcafferkey, bernhard-reiter.
Fixes #60854.
Built from https://develop.svn.wordpress.org/trunk@58614


git-svn-id: http://core.svn.wordpress.org/trunk@58047 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/block-template-utils.php

@@ -606,15 +606,35 @@ function _build_block_template_result_from_file( $template_file, $template_type
 		$template->area = $template_file['area'];
 	}
 
+	$hooked_blocks        = get_hooked_blocks();
+	$has_hooked_blocks    = ! empty( $hooked_blocks ) || has_filter( 'hooked_block_types' );
 	$before_block_visitor = '_inject_theme_attribute_in_template_part_block';
 	$after_block_visitor  = null;
-	$hooked_blocks        = get_hooked_blocks();
+
-	if ( ! empty( $hooked_blocks ) || has_filter( 'hooked_block_types' ) ) {
+	if ( $has_hooked_blocks ) {
 		$before_block_visitor = make_before_block_visitor( $hooked_blocks, $template, 'insert_hooked_blocks_and_set_ignored_hooked_blocks_metadata' );
 		$after_block_visitor  = make_after_block_visitor( $hooked_blocks, $template, 'insert_hooked_blocks_and_set_ignored_hooked_blocks_metadata' );
 	}
-	$blocks            = parse_blocks( $template->content );
+
-	$template->content = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
+	if ( 'wp_template_part' === $template->type && $has_hooked_blocks ) {
+		/**
+		 * In order for hooked blocks to be inserted at positions first_child and last_child in a template part,
+		 * we need to wrap its content a mock template part block and traverse it.
+		 */
+		$content           = get_comment_delimited_block_content(
+			'core/template-part',
+			array(),
+			$template->content
+		);
+		$content           = traverse_and_serialize_blocks( parse_blocks( $content ), $before_block_visitor, $after_block_visitor );
+		$template->content = remove_serialized_parent_block( $content );
+	} else {
+		$template->content = traverse_and_serialize_blocks(
+			parse_blocks( $template->content ),
+			$before_block_visitor,
+			$after_block_visitor
+		);
+	}
 
 	return $template;
 }
@@ -998,8 +1018,28 @@ function _build_block_template_result_from_post( $post ) {
 	if ( ! empty( $hooked_blocks ) || has_filter( 'hooked_block_types' ) ) {
 		$before_block_visitor = make_before_block_visitor( $hooked_blocks, $template, 'insert_hooked_blocks_and_set_ignored_hooked_blocks_metadata' );
 		$after_block_visitor  = make_after_block_visitor( $hooked_blocks, $template, 'insert_hooked_blocks_and_set_ignored_hooked_blocks_metadata' );
-		$blocks               = parse_blocks( $template->content );
+		if ( 'wp_template_part' === $template->type ) {
-		$template->content    = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
+			$existing_ignored_hooked_blocks = get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true );
+			$attributes                     = ! empty( $existing_ignored_hooked_blocks ) ? array( 'metadata' => array( 'ignoredHookedBlocks' => json_decode( $existing_ignored_hooked_blocks, true ) ) ) : array();
+
+			/**
+			 * In order for hooked blocks to be inserted at positions first_child and last_child in a template part,
+			 * we need to wrap its content a mock template part block and traverse it.
+			 */
+			$content           = get_comment_delimited_block_content(
+				'core/template-part',
+				$attributes,
+				$template->content
+			);
+			$content           = traverse_and_serialize_blocks( parse_blocks( $content ), $before_block_visitor, $after_block_visitor );
+			$template->content = remove_serialized_parent_block( $content );
+		} else {
+			$template->content = traverse_and_serialize_blocks(
+				parse_blocks( $template->content ),
+				$before_block_visitor,
+				$after_block_visitor
+			);
+		}
 	}
 
 	return $template;
@@ -1611,7 +1651,36 @@ function inject_ignored_hooked_blocks_metadata_attributes( $changes, $deprecated
 		return $template;
 	}
 
+	if ( 'wp_template_part' === $post->post_type ) {
+		$attributes                     = array();
+		$existing_ignored_hooked_blocks = isset( $post->ID ) ? get_post_meta( $post->ID, '_wp_ignored_hooked_blocks', true ) : '';
+
+		if ( ! empty( $existing_ignored_hooked_blocks ) ) {
+			$attributes['metadata'] = array(
+				'ignoredHookedBlocks' => json_decode( $existing_ignored_hooked_blocks, true ),
+			);
+		}
+
+		$content = get_comment_delimited_block_content(
+			'core/template-part',
+			$attributes,
+			$changes->post_content
+		);
+		$content = apply_block_hooks_to_content( $content, $template, 'set_ignored_hooked_blocks_metadata' );
+		$changes->post_content = remove_serialized_parent_block( $content );
+
+		$wrapper_block_markup  = extract_serialized_parent_block( $content );
+		$wrapper_block         = parse_blocks( $wrapper_block_markup )[0];
+		$ignored_hooked_blocks = $wrapper_block['attrs']['metadata']['ignoredHookedBlocks'] ?? array();
+		if ( ! empty( $ignored_hooked_blocks ) ) {
+			if ( ! isset( $changes->meta_input ) ) {
+				$changes->meta_input = array();
+			}
+			$changes->meta_input['_wp_ignored_hooked_blocks'] = wp_json_encode( $ignored_hooked_blocks );
+		}
+	} else {
 		$changes->post_content = apply_block_hooks_to_content( $changes->post_content, $template, 'set_ignored_hooked_blocks_metadata' );
+	}
 
 	return $changes;
 }

wp-includes/blocks.php

@@ -1045,6 +1045,23 @@ function remove_serialized_parent_block( $serialized_block ) {
 	return substr( $serialized_block, $start, $end - $start );
 }
 
+/**
+ * Accepts the serialized markup of a block and its inner blocks, and returns serialized markup of the wrapper block.
+ *
+ * @since 6.7.0
+ * @access private
+ *
+ * @see remove_serialized_parent_block()
+ *
+ * @param string $serialized_block The serialized markup of a block and its inner blocks.
+ * @return string The serialized markup of the wrapper block.
+ */
+function extract_serialized_parent_block( $serialized_block ) {
+	$start = strpos( $serialized_block, '-->' ) + strlen( '-->' );
+	$end   = strrpos( $serialized_block, '<!--' );
+	return substr( $serialized_block, 0, $start ) . substr( $serialized_block, $end );
+}
+
 /**
  * Updates the wp_postmeta with the list of ignored hooked blocks where the inner blocks are stored as post content.
  * Currently only supports `wp_navigation` post types.

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.7-alpha-58613';
+$wp_version = '6.7-alpha-58614';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.