Comments: Add filter for comment types excluded from queries by default

src/wp-admin/includes/class-wp-comments-list-table.php

@@ -103,12 +103,40 @@ public function prepare_items() {
 			$comment_status = 'all';
 		}
 
+		// The 'note' type is never listed here, so it is dropped from the request.
 		$comment_type = '';
 
 		if ( ! empty( $_REQUEST['comment_type'] ) && 'note' !== $_REQUEST['comment_type'] ) {
 			$comment_type = $_REQUEST['comment_type'];
 		}
 
+		/*
+		 * WP_Comment_Query drops the default exclusions when 'all' types are
+		 * requested, so they are also passed as 'type__not_in' to keep excluded
+		 * types out of the list table in that case.
+		 *
+		 * The requested type is removed from that list, so a plugin that adds
+		 * its own default-excluded type to the type dropdown via
+		 * 'admin_comment_types_dropdown' can still list it. Type aliases are
+		 * expanded first, matching how WP_Comment_Query resolves them.
+		 */
+		switch ( $comment_type ) {
+			case 'comment':
+			case 'comments':
+				$requested_types = array( '', 'comment' );
+				break;
+
+			case 'pings':
+				$requested_types = array( 'pingback', 'trackback' );
+				break;
+
+			default:
+				$requested_types = array( $comment_type );
+				break;
+		}
+
+		$excluded_types = array_values( array_diff( wp_get_default_excluded_comment_types(), $requested_types ) );
+
 		$search = $_REQUEST['s'] ?? '';
 
 		$post_type = ( isset( $_REQUEST['post_type'] ) ) ? sanitize_key( $_REQUEST['post_type'] ) : '';
@@ -155,7 +183,7 @@ public function prepare_items() {
 			'number'                    => $number,
 			'post_id'                   => $post_id,
 			'type'                      => $comment_type,
-			'type__not_in'              => array( 'note' ),
+			'type__not_in'              => $excluded_types,
 			'orderby'                   => $orderby,
 			'order'                     => $order,
 			'post_type'                 => $post_type,

src/wp-admin/includes/comment.php

@@ -223,6 +223,8 @@ function get_comment_to_edit( $id ) {
  *
  * @since 2.3.0
  * @since 6.9.0 Exclude the 'note' comment type from the count.
+ * @since 7.1.0 The excluded comment types are derived from the
+ *              {@see 'default_excluded_comment_types'} filter.
  *
  * @global wpdb $wpdb WordPress database abstraction object.
  *
@@ -242,7 +244,19 @@ function get_pending_comments_num( $post_id ) {
 	$post_id_array = array_map( 'intval', $post_id_array );
 	$post_id_in    = "'" . implode( "', '", $post_id_array ) . "'";
 
-	$pending = $wpdb->get_results( "SELECT comment_post_ID, COUNT(comment_ID) as num_comments FROM $wpdb->comments WHERE comment_post_ID IN ( $post_id_in ) AND comment_approved = '0' AND comment_type != 'note' GROUP BY comment_post_ID", ARRAY_A );
+	$excluded_types = wp_get_default_excluded_comment_types();
+
+	$type_not_in = '';
+	if ( $excluded_types ) {
+		$type_not_in = $wpdb->prepare(
+			sprintf( ' AND comment_type NOT IN ( %s )', implode( ', ', array_fill( 0, count( $excluded_types ), '%s' ) ) ),
+			$excluded_types
+		);
+	}
+
+	// $post_id_in is built from integers and $type_not_in is prepared above.
+	// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared
+	$pending = $wpdb->get_results( "SELECT comment_post_ID, COUNT(comment_ID) as num_comments FROM $wpdb->comments WHERE comment_post_ID IN ( $post_id_in ) AND comment_approved = '0'$type_not_in GROUP BY comment_post_ID", ARRAY_A );
 
 	if ( $single ) {
 		if ( empty( $pending ) ) {

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

@@ -544,6 +544,7 @@ public function get_comments() {
 	 *
 	 * @since 4.4.0
 	 * @since 6.9.0 Excludes the 'note' comment type, unless 'all' or the 'note' types are requested.
+	 * @since 7.1.0 The default-excluded comment types are filterable via {@see 'default_excluded_comment_types'}.
 	 *
 	 * @global wpdb $wpdb WordPress database abstraction object.
 	 *
@@ -779,13 +780,40 @@ protected function get_comment_ids() {
 			'NOT IN' => (array) $this->query_vars['type__not_in'],
 		);
 
-		// Exclude the 'note' comment type, unless 'all' types or the 'note' type explicitly are requested.
-		if (
-			! in_array( 'all', $raw_types['IN'], true ) &&
-			! in_array( 'note', $raw_types['IN'], true ) &&
-			! in_array( 'note', $raw_types['NOT IN'], true )
-		) {
-			$raw_types['NOT IN'][] = 'note';
+		$excluded_types = wp_get_default_excluded_comment_types( $this );
+
+		// Unless all types are requested, exclude each default-excluded type
+		// that the query does not explicitly request. The special type tokens
+		// in the request ('comment', 'comments', 'pings') are first expanded to
+		// the literal comment_type values they represent, so a type requested
+		// via an alias (for example 'pings' for 'pingback' and 'trackback') is
+		// still treated as explicitly requested and is not excluded.
+		if ( ! in_array( 'all', $raw_types['IN'], true ) ) {
+			$requested_types = array();
+			foreach ( $raw_types['IN'] as $requested_type ) {
+				switch ( $requested_type ) {
+					case 'comment':
+					case 'comments':
+						$requested_types[] = '';
+						$requested_types[] = 'comment';
+						break;
+
+					case 'pings':
+						$requested_types[] = 'pingback';
+						$requested_types[] = 'trackback';
+						break;
+
+					default:
+						$requested_types[] = $requested_type;
+						break;
+				}
+			}
+
+			foreach ( $excluded_types as $excluded_type ) {
+				if ( ! in_array( $excluded_type, $requested_types, true ) ) {
+					$raw_types['NOT IN'][] = $excluded_type;
+				}
+			}
 		}
 
 		$comment_types = array();

src/wp-includes/comment.php

@@ -2872,10 +2872,79 @@ function wp_update_comment_count( $post_id, $do_deferred = false ) {
 	return null;
 }
 
+/**
+ * Retrieves the comment types that are excluded from queries and counts by default.
+ *
+ * Applies the {@see 'default_excluded_comment_types'} filter and normalizes the
+ * result: non-scalar values are discarded, the rest are cast to strings, empties
+ * and duplicates are removed, and the special type tokens understood by
+ * WP_Comment_Query ('all', 'comment', 'comments', 'pings') are stripped - the
+ * filter deals in literal `comment_type` values only.
+ *
+ * @since 7.1.0
+ *
+ * @param WP_Comment_Query|null $query Optional. The current query instance when called
+ *                                     from WP_Comment_Query, or null in counting
+ *                                     contexts. Default null.
+ * @return string[] Comment types excluded by default.
+ */
+function wp_get_default_excluded_comment_types( $query = null ) {
+	/**
+	 * Filters the comment types that are excluded from query results by default.
+	 *
+	 * Comment types in this list are omitted from `WP_Comment_Query` results
+	 * unless the query explicitly requests the 'all' type, or explicitly
+	 * includes the specific type via the 'type' or 'type__in' query variables.
+	 *
+	 * This allows plugins to keep comment types out of standard comment
+	 * listings and counts by default, without having to filter every
+	 * query individually. The 'note' comment type, used by the editor, is
+	 * excluded by default. The same set is applied when recalculating a
+	 * post's stored comment count in wp_update_comment_count_now() and when
+	 * counting pending comments, so an excluded type does not inflate
+	 * get_comments_number().
+	 *
+	 * Values must be literal `comment_type` values as stored in the database;
+	 * the special type tokens understood by WP_Comment_Query ('all', 'comment',
+	 * 'comments', 'pings') are ignored, as are values that are not scalar.
+	 *
+	 * Register callbacks for this filter unconditionally (for example on
+	 * 'plugins_loaded' or 'init') rather than toggling them per call: query
+	 * results are cached against the comment `last_changed` key, which does not
+	 * account for this filter's output, so per-call toggling can serve stale
+	 * results from the cache.
+	 *
+	 * This exclusion is a default-visibility convenience, not an access-control
+	 * mechanism: callers can still retrieve excluded types explicitly (for
+	 * example with 'type' => 'all'), so do not rely on this filter to keep
+	 * comment data private. Enforce capability checks wherever the data is
+	 * displayed or exposed (for example over REST).
+	 *
+	 * @since 7.1.0
+	 *
+	 * @param string[]              $excluded_types Comment types excluded from query results by default.
+	 *                                              Default array contains the 'note' type.
+	 * @param WP_Comment_Query|null $query          The WP_Comment_Query instance, or null in counting
+	 *                                              contexts (recalculating a post's stored comment
+	 *                                              count, counting pending comments).
+	 */
+	$excluded_types = apply_filters( 'default_excluded_comment_types', array( 'note' ), $query );
+
+	// Drop values that cannot be cast to a string, so a stray object or array cannot error out.
+	$excluded_types = array_filter( (array) $excluded_types, 'is_scalar' );
+
+	$excluded_types = array_unique( array_filter( array_map( 'strval', $excluded_types ), 'strlen' ) );
+
+	// Strip the special type tokens so an alias cannot poison explicit-type queries.
+	return array_values( array_diff( $excluded_types, array( 'all', 'comment', 'comments', 'pings' ) ) );
+}
+
 /**
  * Updates the comment count for the post.
  *
  * @since 2.5.0
+ * @since 7.1.0 The excluded comment types are derived from the
+ *              {@see 'default_excluded_comment_types'} filter.
  *
  * @global wpdb $wpdb WordPress database abstraction object.
  *
@@ -2914,7 +2983,26 @@ function wp_update_comment_count_now( $post_id ) {
 	$new = apply_filters( 'pre_wp_update_comment_count_now', null, $old, $post_id );
 
 	if ( is_null( $new ) ) {
-		$new = (int) $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM $wpdb->comments WHERE comment_post_ID = %d AND comment_approved = '1' AND comment_type != 'note'", $post_id ) );
+		$excluded_types = wp_get_default_excluded_comment_types();
+
+		if ( $excluded_types ) {
+			$new = (int) $wpdb->get_var(
+				$wpdb->prepare(
+					sprintf(
+						"SELECT COUNT(*) FROM $wpdb->comments WHERE comment_post_ID = %%d AND comment_approved = '1' AND comment_type NOT IN (%s)",
+						implode( ', ', array_fill( 0, count( $excluded_types ), '%s' ) )
+					),
+					array_merge( array( $post_id ), $excluded_types )
+				)
+			);
+		} else {
+			$new = (int) $wpdb->get_var(
+				$wpdb->prepare(
+					"SELECT COUNT(*) FROM $wpdb->comments WHERE comment_post_ID = %d AND comment_approved = '1'",
+					$post_id
+				)
+			);
+		}
 	} else {
 		$new = (int) $new;
 	}

tests/phpunit/tests/admin/includes/comment/GetPendingCommentsNum_Test.php

@@ -0,0 +1,137 @@
+<?php
+
+/**
+ * @group admin
+ * @group comment
+ *
+ * @covers ::get_pending_comments_num
+ */
+class Admin_Includes_Comment_GetPendingCommentsNum_Test extends WP_UnitTestCase {
+
+	/**
+	 * Creates a pending (unapproved) comment of a given type on a post.
+	 *
+	 * @param int    $post_id      Post to attach the comment to.
+	 * @param string $comment_type Comment type slug.
+	 * @return int The new comment ID.
+	 */
+	private function make_pending( $post_id, $comment_type = 'comment' ) {
+		return self::factory()->comment->create(
+			array(
+				'comment_post_ID'  => $post_id,
+				'comment_type'     => $comment_type,
+				'comment_approved' => '0',
+			)
+		);
+	}
+
+	/**
+	 * @ticket 65537
+	 */
+	public function test_counts_only_pending_comments() {
+		$post_id = self::factory()->post->create();
+		$this->make_pending( $post_id );
+		self::factory()->comment->create(
+			array(
+				'comment_post_ID'  => $post_id,
+				'comment_approved' => '1',
+			)
+		);
+
+		$this->assertSame( 1, get_pending_comments_num( $post_id ) );
+	}
+
+	/**
+	 * @ticket 65537
+	 */
+	public function test_excludes_note_type_by_default() {
+		$post_id = self::factory()->post->create();
+		$this->make_pending( $post_id );
+		$this->make_pending( $post_id, 'note' );
+
+		$this->assertSame( 1, get_pending_comments_num( $post_id ) );
+	}
+
+	/**
+	 * A type added to the excluded set must drop out of the pending count.
+	 *
+	 * @ticket 65537
+	 */
+	public function test_excludes_a_filtered_type() {
+		$post_id = self::factory()->post->create();
+		$this->make_pending( $post_id );
+		$this->make_pending( $post_id, 'review' );
+
+		// 'review' is counted by default.
+		$this->assertSame( 2, get_pending_comments_num( $post_id ) );
+
+		$filter = static function ( $types ) {
+			$types[] = 'review';
+			return $types;
+		};
+		add_filter( 'default_excluded_comment_types', $filter );
+		$num = get_pending_comments_num( $post_id );
+		remove_filter( 'default_excluded_comment_types', $filter );
+
+		$this->assertSame( 1, $num );
+	}
+
+	/**
+	 * The exclusion is filter-driven, not a hard-coded 'note' literal.
+	 *
+	 * @ticket 65537
+	 */
+	public function test_emptying_filter_counts_note_type() {
+		$post_id = self::factory()->post->create();
+		$this->make_pending( $post_id, 'note' );
+
+		$this->assertSame( 0, get_pending_comments_num( $post_id ) );
+
+		add_filter( 'default_excluded_comment_types', '__return_empty_array' );
+		$num = get_pending_comments_num( $post_id );
+		remove_filter( 'default_excluded_comment_types', '__return_empty_array' );
+
+		$this->assertSame( 1, $num );
+	}
+
+	/**
+	 * A filter callback returning false degrades gracefully to no exclusions.
+	 *
+	 * Scalar returns are cast to an array and treated as a single excluded type;
+	 * only values that normalize to an empty set disable the exclusions.
+	 *
+	 * @ticket 65537
+	 */
+	public function test_false_filter_return_counts_all_types() {
+		$post_id = self::factory()->post->create();
+		$this->make_pending( $post_id, 'note' );
+
+		add_filter( 'default_excluded_comment_types', '__return_false' );
+		$num = get_pending_comments_num( $post_id );
+		remove_filter( 'default_excluded_comment_types', '__return_false' );
+
+		$this->assertSame( 1, $num );
+	}
+
+	/**
+	 * @ticket 65537
+	 */
+	public function test_array_input_returns_counts_keyed_by_post() {
+		$post_a = self::factory()->post->create();
+		$post_b = self::factory()->post->create();
+		$this->make_pending( $post_a );
+		$this->make_pending( $post_a, 'note' );
+		$this->make_pending( $post_b );
+		$this->make_pending( $post_b );
+
+		$counts = get_pending_comments_num( array( $post_a, $post_b ) );
+
+		$this->assertSame(
+			array(
+				$post_a => 1,
+				$post_b => 2,
+			),
+			$counts
+		);
+	}
+}