Fix: Post_type template is not used when creating a page in site edit…

…or. (#62488)

Co-authored-by: jorgefilipecosta <jorgefilipecosta@git.wordpress.org>
Co-authored-by: oandregal <oandregal@git.wordpress.org>
Co-authored-by: ellatrix <ellatrix@git.wordpress.org>
Co-authored-by: colorful-tones <colorful-tones@git.wordpress.org>
Co-authored-by: fabiankaegy <fabiankaegy@git.wordpress.org>
Co-authored-by: bacoords <bacoords@git.wordpress.org>

lib/rest-api.php

@@ -18,3 +18,49 @@ function gutenberg_register_global_styles_endpoints() {
 	$global_styles_controller->register_routes();
 }
 add_action( 'rest_api_init', 'gutenberg_register_global_styles_endpoints' );
+
+if ( ! function_exists( 'gutenberg_register_wp_rest_post_types_controller_fields' ) ) {
+	/**
+	 * Adds `template` and `template_lock` fields to WP_REST_Post_Types_Controller class.
+	 */
+	function gutenberg_register_wp_rest_post_types_controller_fields() {
+		register_rest_field(
+			'type',
+			'template',
+			array(
+				'get_callback' => function ( $item ) {
+					$post_type = get_post_type_object( $item['slug'] );
+					if ( ! empty( $post_type ) && ! empty( $post_type->template ) ) {
+						return $post_type->template;
+					}
+				},
+				'schema'       => array(
+					'type'        => 'array',
+					'description' => __( 'The template associated with the post type.', 'gutenberg' ),
+					'readonly'    => true,
+					'context'     => array( 'view', 'edit', 'embed' ),
+				),
+			)
+		);
+		register_rest_field(
+			'type',
+			'template_lock',
+			array(
+				'get_callback' => function ( $item ) {
+					$post_type = get_post_type_object( $item['slug'] );
+					if ( ! empty( $post_type ) && ! empty( $post_type->template_lock ) && false !== $post_type->template_lock ) {
+						return $post_type->template_lock;
+					}
+				},
+				'schema'       => array(
+					'type'        => 'string',
+					'enum'        => array( 'all', 'insert', 'contentOnly' ),
+					'description' => __( 'The template_lock specified for the post type.', 'gutenberg' ),
+					'readonly'    => true,
+					'context'     => array( 'view', 'edit', 'embed' ),
+				),
+			)
+		);
+	}
+}
+add_action( 'rest_api_init', 'gutenberg_register_wp_rest_post_types_controller_fields' );

packages/edit-site/src/components/add-new-page/index.js

@@ -9,11 +9,12 @@ import {
 	TextControl,
 } from '@wordpress/components';
 import { __, sprintf } from '@wordpress/i18n';
-import { useDispatch } from '@wordpress/data';
+import { useDispatch, useRegistry } from '@wordpress/data';
 import { useState } from '@wordpress/element';
 import { store as coreStore } from '@wordpress/core-data';
 import { store as noticesStore } from '@wordpress/notices';
 import { decodeEntities } from '@wordpress/html-entities';
+import { serialize, synchronizeBlocksWithTemplate } from '@wordpress/blocks';
 
 export default function AddNewPageModal( { onSave, onClose } ) {
 	const [ isCreatingPage, setIsCreatingPage ] = useState( false );
@@ -22,6 +23,7 @@ export default function AddNewPageModal( { onSave, onClose } ) {
 	const { saveEntityRecord } = useDispatch( coreStore );
 	const { createErrorNotice, createSuccessNotice } =
 		useDispatch( noticesStore );
+	const { resolveSelect } = useRegistry();
 
 	async function createPage( event ) {
 		event.preventDefault();
@@ -31,13 +33,23 @@ export default function AddNewPageModal( { onSave, onClose } ) {
 		}
 		setIsCreatingPage( true );
 		try {
+			const pagePostType =
+				await resolveSelect( coreStore ).getPostType( 'page' );
 			const newPage = await saveEntityRecord(
 				'postType',
 				'page',
 				{
 					status: 'draft',
 					title,
 					slug: title || __( 'No title' ),
+					content: !! pagePostType.template
+						? serialize(
+								synchronizeBlocksWithTemplate(
+									[],
+									pagePostType.template
+								)
+						  )
+						: undefined,
 				},
 				{ throwOnError: true }
 			);