From 4ba54c210415341065d1b95f0a7e694aee9694ab Mon Sep 17 00:00:00 2001
From: Adam Silverstein <adamsilverstein@git.wordpress.org>
Date: Tue, 10 Sep 2019 18:41:03 +0000
Subject: [PATCH] Comments: add a new `comments_pre_query` filter to short
 circuit WP_Comment_Query 'get_comments' queries.

Return a non-null value to bypass WordPress's default comment queries.

Props felipeelia, spacedmonkey.
Fixes #45800.



git-svn-id: https://develop.svn.wordpress.org/trunk@46086 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/class-wp-comment-query.php | 24 +++++++++++++++++
 tests/phpunit/tests/comment/query.php      | 31 ++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/src/wp-includes/class-wp-comment-query.php b/src/wp-includes/class-wp-comment-query.php
index eba9ddf54e..28ac6082e3 100644
--- a/src/wp-includes/class-wp-comment-query.php
+++ b/src/wp-includes/class-wp-comment-query.php
@@ -379,6 +379,30 @@ class WP_Comment_Query {
 			$this->meta_query_clauses = $this->meta_query->get_sql( 'comment', $wpdb->comments, 'comment_ID', $this );
 		}
 
+		$comment_data = null;
+
+		/**
+		 * Filter the comments data before the query takes place.
+		 *
+		 * Return a non-null value to bypass WordPress's default comment queries.
+		 *
+		 * The expected return type from this filter depends on the value passed in the request query_vars:
+		 * When $this->query_vars['count'] is set, the filter should return the comment count as an int.
+		 * When `'ids' == $this->query_vars['fields']`, the filter should return an array of comment ids.
+		 * Otherwise the filter should return an array of WP_Comment objects.
+		 *
+		 * @since 5.3.0
+		 *
+		 * @param array|int|null   $comment_data Return an array of comment data to short-circuit WP's comment query,
+		 *                                       or null to allow WP to run its normal queries.
+		 * @param WP_Comment_Query $this         The WP_Comment_Query instance, passed by reference.
+		 */
+		$comment_data = apply_filters_ref_array( 'comments_pre_query', array( $comment_data, &$this ) );
+
+		if ( null !== $comment_data ) {
+			return $comment_data;
+		}
+
 		/*
 		 * Only use the args defined in the query_var_defaults to compute the key,
 		 * but ignore 'fields', which does not affect query results.
diff --git a/tests/phpunit/tests/comment/query.php b/tests/phpunit/tests/comment/query.php
index 9966f2d1bd..372fa475c4 100644
--- a/tests/phpunit/tests/comment/query.php
+++ b/tests/phpunit/tests/comment/query.php
@@ -4882,4 +4882,35 @@ class Tests_Comment_Query extends WP_UnitTestCase {
 
 		$this->assertEqualSets( $c1, $found );
 	}
+
+	/**
+	 * @ticket 45800
+	 */
+	public function test_comments_pre_query_filter_should_bypass_database_query() {
+		global $wpdb;
+
+		add_filter( 'comments_pre_query', array( __CLASS__, 'filter_comments_pre_query' ), 10, 2 );
+
+		$num_queries = $wpdb->num_queries;
+
+		$q       = new WP_Comment_Query();
+		$results = $q->query( array() );
+
+		remove_filter( 'comments_pre_query', array( __CLASS__, 'filter_comments_pre_query' ), 10, 2 );
+
+		// Make sure no queries were executed.
+		$this->assertSame( $num_queries, $wpdb->num_queries );
+
+		// We manually inserted a non-existing site and overrode the results with it.
+		$this->assertSame( array( 555 ), $results );
+
+		// Make sure manually setting total_users doesn't get overwritten.
+		$this->assertEquals( 1, $q->found_comments );
+	}
+
+	public static function filter_comments_pre_query( $comments, $query ) {
+		$query->found_comments = 1;
+
+		return array( 555 );
+	}
 }