From cb38bc973eaf574dafc92b981ffd1776337e2659 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Thu, 17 Sep 2020 19:53:47 +0000
Subject: [PATCH] Comments: Assign the array of comment data returned from the
 `comments_pre_query` filter to the `comments` property of the current
 `WP_Comment_Query` instance.

This avoids the performance overhead of calling `WP_Comment_Query::get_comments()` twice: first when creating the object instance, then to retrieve the filtered results.

This also makes the filter a bit more consistent with other similar filters, e.g. `posts_pre_query`, `terms_pre_query`, or `users_pre_query`.

Follow-up to [46086].

Props dinhtungdu, imath, spacedmonkey, adamsilverstein, SergeyBiryukov.
Fixes #50521.

git-svn-id: https://develop.svn.wordpress.org/trunk@48990 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/class-wp-comment-query.php | 14 +++++++++++
 tests/phpunit/tests/comment/query.php      | 29 ++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/src/wp-includes/class-wp-comment-query.php b/src/wp-includes/class-wp-comment-query.php
index c04584b9d1..f8836ca80a 100644
--- a/src/wp-includes/class-wp-comment-query.php
+++ b/src/wp-includes/class-wp-comment-query.php
@@ -394,7 +394,17 @@ class WP_Comment_Query {
 		 *   an array of comment IDs.
 		 * - Otherwise the filter should return an array of WP_Comment objects.
 		 *
+		 * Note that if the filter returns an array of comment data, it will be assigned
+		 * to the `comments` property of the current WP_Comment_Query instance.
+		 *
+		 * Filtering functions that require pagination information are encouraged to set
+		 * the `found_comments` and `max_num_pages` properties of the WP_Comment_Query object,
+		 * passed to the filter by reference. If WP_Comment_Query does not perform a database
+		 * query, it will not have enough information to generate these values itself.
+		 *
 		 * @since 5.3.0
+		 * @since 5.6.0 The returned array of comment data is assigned to the `comments` property
+		 *              of the current WP_Comment_Query instance.
 		 *
 		 * @param array|int|null   $comment_data Return an array of comment data to short-circuit WP's comment query,
 		 *                                       the comment count as an integer if `$this->query_vars['count']` is set,
@@ -404,6 +414,10 @@ class WP_Comment_Query {
 		$comment_data = apply_filters_ref_array( 'comments_pre_query', array( $comment_data, &$this ) );
 
 		if ( null !== $comment_data ) {
+			if ( is_array( $comment_data ) && ! $this->query_vars['count'] ) {
+				$this->comments = $comment_data;
+			}
+
 			return $comment_data;
 		}
 
diff --git a/tests/phpunit/tests/comment/query.php b/tests/phpunit/tests/comment/query.php
index 012284eca6..9dab4adc46 100644
--- a/tests/phpunit/tests/comment/query.php
+++ b/tests/phpunit/tests/comment/query.php
@@ -4916,4 +4916,33 @@ class Tests_Comment_Query extends WP_UnitTestCase {
 
 		return array( 555 );
 	}
+
+	/**
+	 * @ticket 50521
+	 */
+	public function test_comments_pre_query_filter_should_set_comments_property() {
+		add_filter( 'comments_pre_query', array( __CLASS__, 'filter_comments_pre_query_and_set_comments' ), 10, 2 );
+
+		$q       = new WP_Comment_Query();
+		$results = $q->query( array() );
+
+		remove_filter( 'comments_pre_query', array( __CLASS__, 'filter_comments_pre_query_and_set_comments' ), 10, 2 );
+
+		// Make sure the comments property is the same as the results.
+		$this->assertSame( $results, $q->comments );
+
+		// Make sure the comment type is `foobar`.
+		$this->assertSame( 'foobar', $q->comments[0]->comment_type );
+	}
+
+	public static function filter_comments_pre_query_and_set_comments( $comments, $query ) {
+		$c = self::factory()->comment->create(
+			array(
+				'comment_type'     => 'foobar',
+				'comment_approved' => '1',
+			)
+		);
+
+		return array( get_comment( $c ) );
+	}
 }