From 948029f5836fa31665339f45e9d149be378ad68d Mon Sep 17 00:00:00 2001
From: Arkeins <7311955+Arkeins@users.noreply.github.com>
Date: Sun, 4 Dec 2022 17:55:12 +0100
Subject: [PATCH] Fix #19693: Fix db/Command not caching `NULL` result with
 scalar fetchMode

---
 framework/CHANGELOG.md           | 2 +-
 framework/db/Command.php         | 2 +-
 tests/framework/db/QueryTest.php | 5 +++++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index c8d1a77e85..eadc5ff691 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -4,12 +4,12 @@ Yii Framework 2 Change Log
 2.0.48 under development
 ------------------------
 
+- Bug #19693: Fix db/Command not caching `NULL` result with scalar fetchMode (Arkeins)
 - Enh #15376: Added cache usage for `yii2\rbac\DbManager::getRolesByUser()` (manchenkoff)
 - Enh #9740: Usage of DI instead of new keyword in Schemas (manchenkoff)
 - Enh #19689: Remove empty elements from the `class` array in `yii\helpers\BaseHtml::renderTagAttributes()` to prevent unwanted spaces (MoritzLost)
 - Chg #19696: Change visibility of `yii\web\View::isPageEnded` to `protected` (lubosdz, samdark)
 
-
 2.0.47 November 18, 2022
 ------------------------
 
diff --git a/framework/db/Command.php b/framework/db/Command.php
index 6f5d5daede..2b8d77ff60 100644
--- a/framework/db/Command.php
+++ b/framework/db/Command.php
@@ -1153,7 +1153,7 @@ class Command extends Component
                 $cache = $info[0];
                 $cacheKey = $this->getCacheKey($method, $fetchMode, '');
                 $result = $cache->get($cacheKey);
-                if (is_array($result) && isset($result[0])) {
+                if (is_array($result) && array_key_exists(0, $result)) {
                     Yii::debug('Query result served from cache', 'yii\db\Command::query');
                     return $result[0];
                 }
diff --git a/tests/framework/db/QueryTest.php b/tests/framework/db/QueryTest.php
index 5dbcc0b0b7..4de2910704 100644
--- a/tests/framework/db/QueryTest.php
+++ b/tests/framework/db/QueryTest.php
@@ -727,6 +727,11 @@ abstract class QueryTest extends DatabaseTestCase
             $this->assertEquals('user1', $query->noCache()->where(['id' => 1])->scalar($db));
             $this->assertEquals('user11', $query->cache()->where(['id' => 1])->scalar($db));
         }, 10);
+
+        $update->bindValues([':id' => 3, ':name' => null])->execute();
+        $this->assertEquals(null, $query->cache()->where(['id' => 3])->scalar($db));
+        $update->bindValues([':id' => 3, ':name' => 'user3'])->execute();
+        $this->assertEquals(null, $query->cache()->where(['id' => 3])->scalar($db), 'Null value should be cached.');
     }