From 6eab41377a8b8937c1b70dbbc31fa784740abf4b Mon Sep 17 00:00:00 2001
From: joshuaruesweg <ruesweg@woltlab.com>
Date: Mon, 27 Sep 2021 13:16:31 +0200
Subject: [PATCH] Fix removing reactions on guests content

Since MySQL 8 the deletion of reactions on contents created by guests might fail. The ReactionHandler tries to update the likesReceived column for a non-existent user, sending the empty string as the userID. Recent versions of MySQL 8 error out with MySQL error 1292. The following MySQL bug appears to be related:

https://bugs.mysql.com/bug.php?id=101806
---
 .../lib/system/reaction/ReactionHandler.class.php    | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php b/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
index c0394173ea..9ec09d24dd 100644
--- a/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
+++ b/wcfsetup/install/files/lib/system/reaction/ReactionHandler.class.php
@@ -687,7 +687,7 @@ class ReactionHandler extends SingletonFactory
         // reduce count of received users
         $users = [];
         foreach ($likeObjects as $likeObject) {
-            if ($likeObject->likes) {
+            if ($likeObject->likes && $likeObject->objectUserID) {
                 if (!isset($users[$likeObject->objectUserID])) {
                     $users[$likeObject->objectUserID] = 0;
                 }
@@ -699,7 +699,7 @@ class ReactionHandler extends SingletonFactory
         foreach ($users as $userID => $reactionData) {
             $userEditor = new UserEditor(new User(null, ['userID' => $userID]));
             $userEditor->updateCounters([
-                'likesReceived' => $users[$userID],
+                'likesReceived' => $reactionData,
             ]);
         }
 
@@ -714,10 +714,12 @@ class ReactionHandler extends SingletonFactory
             foreach ($likeList as $like) {
                 $likeData[$like->likeID] = $like->userID;
 
-                if (!isset($activityPoints[$like->objectUserID])) {
-                    $activityPoints[$like->objectUserID] = 0;
+                if ($like->objectUserID) {
+                    if (!isset($activityPoints[$like->objectUserID])) {
+                        $activityPoints[$like->objectUserID] = 0;
+                    }
+                    $activityPoints[$like->objectUserID]++;
                 }
-                $activityPoints[$like->objectUserID]++;
             }
 
             // delete like notifications
-- 
2.20.1