Ticket #39578: 39578.2.diff

src/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php

@@ -552 +552 @@
                  * Filters a comment before it is inserted via the REST API.
                  *
                  * Allows modification of the comment right before it is inserted via wp_insert_comment().
+                 * Returning a WP_Error value from the filter will shortcircuit insertion and allow
+                 * skipping further processing.
                  *
                  * @since 4.7.0
+                 * @since 4.8.0 $prepared_comment can now be a WP_Error to shortcircuit insertion.
                  *
-                 * @param array           $prepared_comment The prepared comment data for wp_insert_comment().
+                 * @param array|WP_Error  $prepared_comment The prepared comment data for wp_insert_comment().
                  * @param WP_REST_Request $request          Request used to insert the comment.
                  */
                 $prepared_comment = apply_filters( 'rest_pre_insert_comment', $prepared_comment, $request );
+                if ( is_wp_error( $prepared_comment ) ) {
+                        return $prepared_comment;
+                }
 
                 $comment_id = wp_insert_comment( wp_filter_comment( wp_slash( (array) $prepared_comment ) ) );