Patterns, Templates: Inject theme attr into Template Part blocks.

It was found that Template Part blocks were broken in the Site Editor, showing the `Template part has been deleted or is unavailable` message, due to a missing `theme` attribute.

This bug seems to have been introduced by [56896], whose goal was to only inject that attribute into the markup returned by the templates and patterns REST API endpoints but not on the frontend, in order to improve performance. It has been demonstrated locally that reverting that changeset fixes the bug.

Reverts [56896].
Props mmcalister, swisspidy, thelovelist, hellofromTonya, pbiron, Pauthake015, richtabor, nicolefurlan, huzaifaalmesbah, annezazu, kafleg, aegkr, sunitarai, shresthaaman, andraganescu, onemaggie, gziolo.
Fixes #59629.
Built from https://develop.svn.wordpress.org/trunk@56960


git-svn-id: https://core.svn.wordpress.org/trunk@56471 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/block-template-utils.php

@@ -547,18 +547,15 @@ function _build_block_template_result_from_file( $template_file, $template_type
 		$template->area = $template_file['area'];
 	}
 
-	$before_block_visitor = ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ? '_inject_theme_attribute_in_template_part_block' : null;
+	$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' ) ) {
 		$before_block_visitor = make_before_block_visitor( $hooked_blocks, $template );
 		$after_block_visitor  = make_after_block_visitor( $hooked_blocks, $template );
 	}
-	if ( null !== $before_block_visitor || null !== $after_block_visitor ) {
-		$blocks           = parse_blocks( $template_content );
-		$template_content = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
-	}
-	$template->content = $template_content;
+	$blocks            = parse_blocks( $template_content );
+	$template->content = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
 
 	return $template;
 }

wp-includes/blocks.php

@@ -779,9 +779,7 @@ function make_before_block_visitor( $hooked_blocks, $context ) {
 	 * @return string The serialized markup for the given block, with the markup for any hooked blocks prepended to it.
 	 */
 	return function ( &$block, $parent_block = null, $prev = null ) use ( $hooked_blocks, $context ) {
-		if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
-			_inject_theme_attribute_in_template_part_block( $block );
-		}
+		_inject_theme_attribute_in_template_part_block( $block );
 
 		$markup = '';
 

wp-includes/class-wp-block-patterns-registry.php

@@ -165,16 +165,14 @@ public function unregister( $pattern_name ) {
 	private function prepare_content( $pattern, $hooked_blocks ) {
 		$content = $pattern['content'];
 
-		$before_block_visitor = ( defined( 'REST_REQUEST' ) && REST_REQUEST ) ? '_inject_theme_attribute_in_template_part_block' : null;
+		$before_block_visitor = '_inject_theme_attribute_in_template_part_block';
 		$after_block_visitor  = null;
 		if ( ! empty( $hooked_blocks ) || has_filter( 'hooked_block_types' ) ) {
 			$before_block_visitor = make_before_block_visitor( $hooked_blocks, $pattern );
 			$after_block_visitor  = make_after_block_visitor( $hooked_blocks, $pattern );
 		}
-		if ( null !== $before_block_visitor || null !== $after_block_visitor ) {
-			$blocks  = parse_blocks( $content );
-			$content = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
-		}
+		$blocks  = parse_blocks( $content );
+		$content = traverse_and_serialize_blocks( $blocks, $before_block_visitor, $after_block_visitor );
 
 		return $content;
 	}

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-beta4-56959';
+$wp_version = '6.4-beta4-56960';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.