fix(Validation): correct required_without logic and prevent array key warnings

system/Validation/Rules.php

@@ -429,15 +429,22 @@ public function required_without(
 
                 $fieldData       = dot_array_search($otherField, $data);
                 $fieldSplitArray = explode('.', $field);
-                $fieldKey        = $fieldSplitArray[1];
+                $fieldKey        = $fieldSplitArray[1] ?? null;
 
                 if (is_array($fieldData)) {
-                    return ! empty(dot_array_search($otherField, $data)[$fieldKey]);
+                    if (empty($fieldData[$fieldKey])) {
+                        return false;
+                    }
+
+                    continue;
                 }
-                $nowField      = str_replace('*', $fieldKey, $otherField);
+
+                $nowField      = str_replace('*', (string) $fieldKey, $otherField);
                 $nowFieldVaule = dot_array_search($nowField, $data);
 
-                return null !== $nowFieldVaule;
+                if (null === $nowFieldVaule) {
+                    return false;
+                }
             }
         }
 

tests/system/Validation/ValidationTest.php

@@ -1854,6 +1854,28 @@ public function testRequireWithoutWithAsterisk(): void
         );
     }
 
+    /**
+     * Test that `required_without` checks all fields in dot-notation when there are multiple fields.
+     */
+    public function testRequireWithoutMultipleWithAsterisk(): void
+    {
+        $data = [
+            'a' => [
+                ['b' => 1, 'c' => 2, 'd' => ''],
+                ['b' => 1, 'c' => '', 'd' => ''],
+            ],
+        ];
+
+        $this->validation->setRules([
+            'a.*.d' => 'required_without[a.*.b,a.*.c]',
+        ])->run($data);
+
+        $this->assertSame(
+            'The a.*.d field is required when a.*.b,a.*.c is not present.',
+            $this->validation->getError('a.1.d'),
+        );
+    }
+
     /**
      * @see https://github.com/codeigniter4/CodeIgniter4/issues/8128
      */