Allow plugins to add new items to the "Add new" menu on the Site Editor

lib/compat/wordpress-6.1/template-parts-screen.php

@@ -103,6 +103,8 @@ static function( $classes ) {
 		}
 	);
 
+	$extra_template_types = apply_filters( 'extra_template_types', array() );
+
 	$indexed_template_types = array();
 	foreach ( get_default_block_template_types() as $slug => $template_type ) {
 		$template_type['slug']    = (string) $slug;
@@ -114,6 +116,7 @@ static function( $classes ) {
 		'siteUrl'                   => site_url(),
 		'postsPerPage'              => get_option( 'posts_per_page' ),
 		'styles'                    => get_block_editor_theme_styles(),
+		'extraTemplateTypes'        => $extra_template_types,
 		'defaultTemplateTypes'      => $indexed_template_types,
 		'defaultTemplatePartAreas'  => get_allowed_block_template_part_areas(),
 		'supportsLayout'            => wp_theme_has_theme_json(),

lib/compat/wordpress-6.2/template-parts-screen.php

@@ -0,0 +1,43 @@
+<?php
+
+/**
+ * Initialize the editor for the screen. Most of this is copied from `site-editor.php`.
+ *
+ * Note: Parts that need to be ported back should have inline comments.
+ *
+ * @return void
+ */
+function gutenberg_add_custom_settings() {
+	$extra_template_types = apply_filters( 'extra_template_types', array() );
+
+	$indexed_template_types = array();
+	foreach ( get_default_block_template_types() as $slug => $template_type ) {
+		$template_type['slug']    = (string) $slug;
+		$indexed_template_types[] = $template_type;
+	}
+
+	$block_editor_context = new WP_Block_Editor_Context( array( 'name' => 'core/edit-site' ) );
+	$custom_settings      = array(
+		'siteUrl'                   => site_url(),
+		'postsPerPage'              => get_option( 'posts_per_page' ),
+		'styles'                    => get_block_editor_theme_styles(),
+		'extraTemplateTypes'        => $extra_template_types,
+		'defaultTemplateTypes'      => $indexed_template_types,
+		'defaultTemplatePartAreas'  => get_allowed_block_template_part_areas(),
+		'supportsLayout'            => wp_theme_has_theme_json(),
+		'supportsTemplatePartsMode' => ! wp_is_block_theme() && current_theme_supports( 'block-template-parts' ),
+	);
+
+	$editor_settings = get_block_editor_settings( $custom_settings, $block_editor_context );
+
+	wp_add_inline_script(
+		'wp-edit-site',
+		sprintf(
+			'wp.domReady( function() {
+				wp.editSite.initializeEditor( "site-editor", %s );
+			} );',
+			wp_json_encode( $editor_settings )
+		)
+	);
+}
+add_action( 'admin_enqueue_scripts', 'gutenberg_add_custom_settings' );

lib/load.php

@@ -108,6 +108,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 require __DIR__ . '/compat/wordpress-6.2/class-wp-theme-json-6-2.php';
 require __DIR__ . '/compat/wordpress-6.2/edit-form-blocks.php';
 require __DIR__ . '/compat/wordpress-6.2/site-editor.php';
+require __DIR__ . '/compat/wordpress-6.2/template-parts-screen.php';
 
 // Experimental features.
 remove_action( 'plugins_loaded', '_wp_theme_json_webfonts_handler' ); // Turns off WP 6.0's stopgap handler for Webfonts API.

packages/edit-site/src/components/add-new-template/new-template.js

@@ -42,6 +42,7 @@ import {
 	usePostTypeMenuItems,
 	useAuthorMenuItem,
 	usePostTypeArchiveMenuItems,
+	useExtraTemplateTypes,
 } from './utils';
 import AddCustomGenericTemplateModal from './add-custom-generic-template-modal';
 import TemplateActionsLoadingScreen from './template-actions-loading-screen';
@@ -269,12 +270,13 @@ function useMissingTemplates(
 ) {
 	const existingTemplates = useExistingTemplates();
 	const defaultTemplateTypes = useDefaultTemplateTypes();
+	const extraTemplateTypes = useExtraTemplateTypes();
 	const existingTemplateSlugs = ( existingTemplates || [] ).map(
 		( { slug } ) => slug
 	);
 	const missingDefaultTemplates = ( defaultTemplateTypes || [] ).filter(
 		( template ) =>
-			DEFAULT_TEMPLATE_SLUGS.includes( template.slug ) &&
+			[ ...DEFAULT_TEMPLATE_SLUGS ].includes( template.slug ) &&
 			! existingTemplateSlugs.includes( template.slug )
 	);
 	const onClickMenuItem = ( _entityForSuggestions ) => {
@@ -326,6 +328,7 @@ function useMissingTemplates(
 		...usePostTypeArchiveMenuItems(),
 		...postTypesMenuItems,
 		...taxonomiesMenuItems,
+		...extraTemplateTypes,
 	];
 	return missingTemplates;
 }

packages/edit-site/src/components/add-new-template/utils.js

@@ -59,6 +59,11 @@ export const useDefaultTemplateTypes = () => {
 		[]
 	);
 };
+export const useExtraTemplateTypes = () => {
+	return useSelect( ( select ) => {
+		return select( editorStore ).__experimentalGetExtraTemplateTypes();
+	}, [] );
+};
 
 const usePublicPostTypes = () => {
 	const postTypes = useSelect(

packages/edit-site/src/index.js

@@ -84,6 +84,7 @@ export function reinitializeEditor( target, settings ) {
 		dispatch( editorStore ).updateEditorSettings( {
 			defaultTemplateTypes: settings.defaultTemplateTypes,
 			defaultTemplatePartAreas: settings.defaultTemplatePartAreas,
+			extraTemplateTypes: settings.extraTemplateTypes,
 		} );
 	}
 

packages/editor/src/store/selectors.js

@@ -1549,6 +1549,17 @@ export function __experimentalGetDefaultTemplateTypes( state ) {
 	return getEditorSettings( state )?.defaultTemplateTypes;
 }
 
+/**
+ * Returns the extra template slugs.
+ *
+ * @param {Object} state Global application state.
+ *
+ * @return {Array} The template slugs.
+ */
+export function __experimentalGetExtraTemplateTypes( state ) {
+	return getEditorSettings( state )?.extraTemplateTypes;
+}
+
 /**
  * Returns the default template part areas.
  *