Navigation screen: Add opt-in Navigation block rendering

Allows themes to opt-in to having `wp_nav_menu()` render a complete
Navigation block in place of the menu. This allows arbitrarily complex
Navigation block structures can be used in an existing theme.

When a theme declares `add_theme_support( 'block-nav-menus' )`, users
are able to add non-link blocks to a Navigation using the Navigation
screen.

This block tree is stored as menu items and re-assembled into a
Navigation block for display using `render_block()` in the frontend.

Non-link blocks are stored using a menu item with type `'block'` which
renders properly in `nav-menus.php`. This allows users to switch to a
theme that does not support block menus and still see their data in WP
Admin.

lib/class-wp-rest-menu-items-controller.php

@@ -440,10 +440,10 @@ protected function prepare_item_for_database( $request ) {
 			}
 		}
 
-		// If menu item is type html, then content is required.
-		if ( 'html' === $prepared_nav_item['menu-item-type'] ) {
+		// If menu item is type block, then content is required.
+		if ( 'block' === $prepared_nav_item['menu-item-type'] ) {
 			if ( empty( $prepared_nav_item['menu-item-content'] ) ) {
-				return new WP_Error( 'rest_content_required', __( 'Content required if menu item of type html.', 'gutenberg' ), array( 'status' => 400 ) );
+				return new WP_Error( 'rest_content_required', __( 'Content required if menu item of type block.', 'gutenberg' ), array( 'status' => 400 ) );
 			}
 		}
 
@@ -819,7 +819,7 @@ public function get_item_schema() {
 		$schema['properties']['type'] = array(
 			'description' => __( 'The family of objects originally represented, such as "post_type" or "taxonomy".', 'gutenberg' ),
 			'type'        => 'string',
-			'enum'        => array( 'taxonomy', 'post_type', 'post_type_archive', 'custom', 'html' ),
+			'enum'        => array( 'taxonomy', 'post_type', 'post_type_archive', 'custom', 'block' ),
 			'context'     => array( 'view', 'edit', 'embed' ),
 			'default'     => 'custom',
 		);
@@ -894,7 +894,7 @@ public function get_item_schema() {
 		);
 
 		$schema['properties']['content'] = array(
-			'description' => __( 'HTML content to display for this menu item. May contain blocks.', 'gutenberg' ),
+			'description' => __( 'HTML content to display for this block menu item.', 'gutenberg' ),
 			'context'     => array( 'view', 'edit', 'embed' ),
 			'type'        => 'object',
 			'arg_options' => array(

lib/compat.php

@@ -532,114 +532,6 @@ function gutenberg_render_block_with_assigned_block_context( $pre_render, $parse
 }
 add_filter( 'pre_render_block', 'gutenberg_render_block_with_assigned_block_context', 9, 2 );
 
-/**
- * Shim that hooks into `wp_update_nav_menu_item` and makes it so that nav menu
- * items support a 'content' field. This field contains HTML and is used by nav
- * menu items with `type` set to `'html'`.
- *
- * Specifically, this shim makes it so that:
- *
- * 1) The `wp_update_nav_menu_item()` function supports setting
- * `'menu-item-content'` on a menu item. When merged to Core, this functionality
- * should exist in `wp_update_nav_menu_item()`.
- *
- * 2) The `customize_save` ajax action supports setting `'content'` on a nav
- * menu item. When merged to Core, this functionality should exist in
- * `WP_Customize_Manager::save()`.
- *
- * This shim can be removed when the Gutenberg plugin requires a WordPress
- * version that has the ticket below.
- *
- * @see https://core.trac.wordpress.org/ticket/50544
- *
- * @param int   $menu_id         ID of the updated menu.
- * @param int   $menu_item_db_id ID of the new menu item.
- * @param array $args            An array of arguments used to update/add the menu item.
- */
-function gutenberg_update_nav_menu_item_content( $menu_id, $menu_item_db_id, $args ) {
-	global $wp_customize;
-
-	// Support setting content in customize_save admin-ajax.php requests by
-	// grabbing the unsanitized $_POST values.
-	if ( isset( $wp_customize ) ) {
-		$values = $wp_customize->unsanitized_post_values();
-		if ( isset( $values[ "nav_menu_item[$menu_item_db_id]" ]['content'] ) ) {
-			if ( is_string( $values[ "nav_menu_item[$menu_item_db_id]" ]['content'] ) ) {
-				$args['menu-item-content'] = $values[ "nav_menu_item[$menu_item_db_id]" ]['content'];
-			} elseif ( isset( $values[ "nav_menu_item[$menu_item_db_id]" ]['content']['raw'] ) ) {
-				$args['menu-item-content'] = $values[ "nav_menu_item[$menu_item_db_id]" ]['content']['raw'];
-			}
-		}
-	}
-
-	$defaults = array(
-		'menu-item-content' => '',
-	);
-
-	$args = wp_parse_args( $args, $defaults );
-
-	update_post_meta( $menu_item_db_id, '_menu_item_content', wp_slash( $args['menu-item-content'] ) );
-}
-add_action( 'wp_update_nav_menu_item', 'gutenberg_update_nav_menu_item_content', 10, 3 );
-
-/**
- * Shim that hooks into `wp_setup_nav_menu_items` and makes it so that nav menu
- * items have a 'content' field. This field contains HTML and is used by nav
- * menu items with `type` set to `'html'`.
- *
- * Specifically, this shim makes it so that the `wp_setup_nav_menu_item()`
- * function sets `content` on the returned menu item. When merged to Core, this
- * functionality should exist in `wp_setup_nav_menu_item()`.
- *
- * This shim can be removed when the Gutenberg plugin requires a WordPress
- * version that has the ticket below.
- *
- * @see https://core.trac.wordpress.org/ticket/50544
- *
- * @param object $menu_item The menu item object.
- */
-function gutenberg_setup_html_nav_menu_item( $menu_item ) {
-	if ( 'html' === $menu_item->type ) {
-		$menu_item->type_label = __( 'HTML', 'gutenberg' );
-		$menu_item->content    = ! isset( $menu_item->content ) ? get_post_meta( $menu_item->db_id, '_menu_item_content', true ) : $menu_item->content;
-	}
-
-	return $menu_item;
-}
-add_filter( 'wp_setup_nav_menu_item', 'gutenberg_setup_html_nav_menu_item' );
-
-/**
- * Shim that hooks into `walker_nav_menu_start_el` and makes it so that the
- * default walker which renders a menu will correctly render the HTML associated
- * with any navigation menu item that has `type` set to `'html`'.
- *
- * Specifically, this shim makes it so that `Walker_Nav_Menu::start_el()`
- * renders the `content` of a nav menu item when its `type` is `'html'`. When
- * merged to Core, this functionality should exist in
- * `Walker_Nav_Menu::start_el()`.
- *
- * This shim can be removed when the Gutenberg plugin requires a WordPress
- * version that has the ticket below.
- *
- * @see https://core.trac.wordpress.org/ticket/50544
- *
- * @param string   $item_output The menu item's starting HTML output.
- * @param WP_Post  $item        Menu item data object.
- * @param int      $depth       Depth of menu item. Used for padding.
- * @param stdClass $args        An object of wp_nav_menu() arguments.
- */
-function gutenberg_output_html_nav_menu_item( $item_output, $item, $depth, $args ) {
-	if ( 'html' === $item->type ) {
-		$item_output = $args->before;
-		/** This filter is documented in wp-includes/post-template.php */
-		$item_output .= apply_filters( 'the_content', $item->content );
-		$item_output .= $args->after;
-	}
-
-	return $item_output;
-}
-add_filter( 'walker_nav_menu_start_el', 'gutenberg_output_html_nav_menu_item', 10, 4 );
-
 /**
  * Amends the paths to preload when initializing edit post.
  *

lib/load.php

@@ -108,6 +108,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 require dirname( __FILE__ ) . '/block-directory.php';
 require dirname( __FILE__ ) . '/demo.php';
 require dirname( __FILE__ ) . '/widgets.php';
+require dirname( __FILE__ ) . '/navigation.php';
 require dirname( __FILE__ ) . '/navigation-page.php';
 require dirname( __FILE__ ) . '/experiments-page.php';
 require dirname( __FILE__ ) . '/customizer.php';

lib/navigation-page.php

@@ -63,6 +63,7 @@ function gutenberg_navigation_init( $hook ) {
 		'imageSizes'             => $available_image_sizes,
 		'isRTL'                  => is_rtl(),
 		'maxUploadFileSize'      => $max_upload_size,
+		'blockNavMenus'          => get_theme_support( 'block-nav-menus' ),
 	);
 
 	list( $color_palette, ) = (array) get_theme_support( 'editor-color-palette' );