From b05ad49a1943ca2f876ed23658d523cabf8b33a2 Mon Sep 17 00:00:00 2001
From: Oleg Poludnenko <ua.oleg@gmail.com>
Date: Mon, 11 Sep 2023 19:38:41 +0300
Subject: [PATCH 1/2] trim(): Passing null to parameter #1 ($string) of type
 string is deprecated

---
 framework/db/Query.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/framework/db/Query.php b/framework/db/Query.php
index f0b215859dc..1819c9c3107 100644
--- a/framework/db/Query.php
+++ b/framework/db/Query.php
@@ -1049,7 +1049,7 @@ public function rightJoin($table, $on = '', $params = [])
 
     /**
      * Sets the GROUP BY part of the query.
-     * @param string|array|ExpressionInterface $columns the columns to be grouped by.
+     * @param string|array|ExpressionInterface|null $columns the columns to be grouped by.
      * Columns can be specified in either a string (e.g. "id, name") or an array (e.g. ['id', 'name']).
      * The method will automatically quote the column names unless a column contains some parenthesis
      * (which means the column contains a DB expression).
@@ -1067,7 +1067,7 @@ public function groupBy($columns)
     {
         if ($columns instanceof ExpressionInterface) {
             $columns = [$columns];
-        } elseif (!is_array($columns)) {
+        } elseif (!is_array($columns) && !is_null($columns)) {
             $columns = preg_split('/\s*,\s*/', trim($columns), -1, PREG_SPLIT_NO_EMPTY);
         }
         $this->groupBy = $columns;

From fd5c1bbf275702e88012bcedd22f0af86de2ba1f Mon Sep 17 00:00:00 2001
From: Oleg Poludnenko <ua.oleg@gmail.com>
Date: Wed, 20 Sep 2023 12:27:33 +0300
Subject: [PATCH 2/2] Update CHANGELOG.md

---
 framework/CHANGELOG.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/framework/CHANGELOG.md b/framework/CHANGELOG.md
index e468b61f786..e2eefa083b9 100644
--- a/framework/CHANGELOG.md
+++ b/framework/CHANGELOG.md
@@ -7,6 +7,7 @@ Yii Framework 2 Change Log
 - Bug #19925: Improved PHP version check when handling MIME types (schmunk42)
 - Bug #19940: File Log writer without newline (terabytesoftw)
 - Bug #19951: Removed unneeded MIME file tests (schmunk42)
+- Bug #19950: Fix `Query::groupBy(null)` causes error for PHP 8.1: `trim(): Passing null to parameter #1 ($string) of type string is deprecated`
 
 
 2.0.49 August 29, 2023