Comments: Add a REST API endpoint for comment types

src/wp-includes/class-wp-comment-type.php

@@ -89,6 +89,19 @@ final class WP_Comment_Type {
 	 */
 	public $internal = false;
 
+	/**
+	 * Whether to include this comment type in the REST API.
+	 *
+	 * Comment types with this enabled are exposed by the read-only
+	 * `/wp/v2/comment-types` discovery endpoint (name, slug, description,
+	 * labels). It does not affect whether comments of this type are readable
+	 * or queryable via `/wp/v2/comments`. Default is the value of $public.
+	 *
+	 * @since 7.1.0
+	 * @var bool
+	 */
+	public $show_in_rest;
+
 	/**
 	 * Whether this comment type is a native or "built-in" comment type.
 	 *
@@ -183,15 +196,27 @@ public function set_props( $args ) {
 		 * treated as a provided value and overwrite the default name with false.
 		 */
 		$defaults = array(
-			'labels'      => array(),
-			'description' => '',
-			'public'      => true,
-			'internal'    => false,
-			'_builtin'    => false,
+			'labels'       => array(),
+			'description'  => '',
+			'public'       => true,
+			'internal'     => false,
+			'show_in_rest' => null,
+			'_builtin'     => false,
 		);
 
 		$args = array_merge( $defaults, $args );
 
+		/*
+		 * If not set, default 'show_in_rest' to the setting for 'public'. This
+		 * deliberately diverges from WP_Post_Type, which defaults it to false only
+		 * for backward compatibility with post types registered before the REST API
+		 * existed. A new registry has no such constraint, and 'show_in_rest' gates
+		 * only the read-only comment-types discovery endpoint.
+		 */
+		if ( null === $args['show_in_rest'] ) {
+			$args['show_in_rest'] = $args['public'];
+		}
+
 		$args['name'] = $this->name;
 
 		/*

src/wp-includes/comment.php

@@ -413,9 +413,11 @@ function create_initial_comment_types() {
  *  - `public` states display-surface intent: whether the type is meant to be seen by site
  *    visitors. It does not affect what queries return.
  *  - `internal` marks the type as excluded from comment queries and counts by default.
+ *  - `show_in_rest` controls REST discovery of the type's metadata, and nothing else.
  *
- * An argument never implies another argument. The one cascade planned for the future is
- * `show_in_rest`, which will default from `public`.
+ * An argument never implies another argument, with one deliberate exception:
+ * `show_in_rest` defaults from `public`, since a type meant to be seen is a type worth
+ * discovering.
  *
  * Registrations live in a per-process global. Like post types, they are not scoped to a
  * site on multisite: a type registered by one site's plugins is visible after
@@ -434,22 +436,27 @@ function create_initial_comment_types() {
  * @param array|string $args {
  *     Optional. Array or string of arguments for registering a comment type. Default empty array.
  *
- *     @type string     $label       Name of the comment type. Usually plural.
- *                                   Default is the value of $labels['name'].
- *     @type string[]   $labels      An array of labels for this comment type. If not set, the
- *                                   default comment labels are used. See get_comment_type_labels()
- *                                   for a full list of supported labels.
- *     @type string     $description A short descriptive summary of what the comment type is.
- *                                   Default empty.
- *     @type bool       $public      Whether the comment type is intended for use publicly either via
- *                                   the admin interface or by front-end users. Core does not
- *                                   currently act on this argument. Default true.
- *     @type bool       $internal    Whether the comment type is for internal use only. Internal types
- *                                   are excluded from comment queries and counts by default, through
- *                                   the {@see 'default_excluded_comment_types'} filter. Default false.
- *     @type bool       $_builtin    For internal core use only. Marks the type as native to
- *                                   WordPress, which blocks it from being re-registered or
- *                                   unregistered. Default false.
+ *     @type string     $label        Name of the comment type. Usually plural.
+ *                                    Default is the value of $labels['name'].
+ *     @type string[]   $labels       An array of labels for this comment type. If not set, the
+ *                                    default comment labels are used. See get_comment_type_labels()
+ *                                    for a full list of supported labels.
+ *     @type string     $description  A short descriptive summary of what the comment type is.
+ *                                    Default empty.
+ *     @type bool       $public       Whether the comment type is intended for use publicly either via
+ *                                    the admin interface or by front-end users. Core does not
+ *                                    currently act on this argument. Default true.
+ *     @type bool       $internal     Whether the comment type is for internal use only. Internal types
+ *                                    are excluded from comment queries and counts by default, through
+ *                                    the {@see 'default_excluded_comment_types'} filter. Default false.
+ *     @type bool       $show_in_rest Whether to expose this comment type in the REST API comment types
+ *                                    discovery endpoint (`/wp/v2/comment-types`). Exposing a type
+ *                                    reveals its name, slug, description, and labels only; it does not
+ *                                    make comments of this type readable or queryable via
+ *                                    `/wp/v2/comments`. Default is the value of $public.
+ *     @type bool       $_builtin     For internal core use only. Marks the type as native to
+ *                                    WordPress, which blocks it from being re-registered or
+ *                                    unregistered. Default false.
  * }
  * @return WP_Comment_Type|WP_Error The registered comment type object on success,
  *                                  WP_Error object on failure.

src/wp-includes/rest-api.php

@@ -324,6 +324,10 @@ function create_initial_rest_routes() {
 	$controller = new WP_REST_Comments_Controller();
 	$controller->register_routes();
 
+	// Comment types.
+	$controller = new WP_REST_Comment_Types_Controller();
+	$controller->register_routes();
+
 	$search_handlers = array(
 		new WP_REST_Post_Search_Handler(),
 		new WP_REST_Term_Search_Handler(),