fix: preserve sub-second precision in BaseModel datetime timestamps

system/BaseModel.php

@@ -1425,9 +1425,11 @@ protected function doProtectFieldsForInsert(array $row): array
      */
     protected function setDate(?int $userDate = null)
     {
-        $currentDate = $userDate ?? Time::now()->getTimestamp();
+        if ($userDate === null && $this->dateFormat === 'datetime') {
+            return $this->timeToDate(Time::now());
+        }
 
-        return $this->intToDate($currentDate);
+        return $this->intToDate($userDate ?? Time::now()->getTimestamp());
     }
 
     /**

tests/system/Models/GeneralModelTest.php

@@ -15,8 +15,11 @@
 
 use CodeIgniter\Database\BaseConnection;
 use CodeIgniter\Exceptions\BadMethodCallException;
+use CodeIgniter\I18n\Time;
 use CodeIgniter\Model;
 use CodeIgniter\Test\CIUnitTestCase;
+use CodeIgniter\Test\Mock\MockConnection;
+use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Attributes\Group;
 use Tests\Support\Models\JobModel;
 use Tests\Support\Models\UserModel;
@@ -39,6 +42,7 @@ protected function tearDown(): void
     {
         parent::tearDown();
         $this->resetServices();
+        Time::setTestNow();
     }
 
     /**
@@ -111,6 +115,28 @@ public function testSetAllowedFields(): void
         $this->assertSame($allowed2, $this->getPrivateProperty($model, 'allowedFields'));
     }
 
+    #[DataProvider('provideCurrentTimestampPreservesSubseconds')]
+    public function testCurrentTimestampPreservesSubseconds(string $format, string $expected): void
+    {
+        Time::setTestNow('2024-07-09 09:13:34.654321');
+
+        $db    = new MockConnection(['dateFormat' => ['datetime' => $format]]);
+        $model = $this->createModel(UserModel::class, $db);
+        $date  = self::getPrivateMethodInvoker($model, 'setDate');
+
+        $this->assertSame($expected, $date());
+    }
+
+    /**
+     * @return iterable<string, array{string, string}>
+     */
+    public static function provideCurrentTimestampPreservesSubseconds(): iterable
+    {
+        yield 'milliseconds' => ['Y-m-d H:i:s.v', '2024-07-09 09:13:34.654'];
+
+        yield 'microseconds' => ['Y-m-d H:i:s.u', '2024-07-09 09:13:34.654321'];
+    }
+
     public function testBuilderUsesModelTable(): void
     {
         $builder = $this->createModel(UserModel::class)->builder();