Fix: Validation of fields with a leading asterisk.

system/Validation/Validation.php

@@ -147,7 +147,9 @@ public function run(?array $data = null, ?string $group = null, ?string $dbGroup
 
             if (strpos($field, '*') !== false) {
                 $values = array_filter(array_flatten_with_dots($data), static fn ($key) => preg_match(
-                    '/^' . str_replace('\.\*', '\..+', preg_quote($field, '/')) . '$/',
+                    '/^'
+                    . str_replace(['\.\*', '\*\.'], ['\..+', '.+\.'], preg_quote($field, '/'))
+                    . '$/',
                     $key
                 ), ARRAY_FILTER_USE_KEY);
                 // if keys not found
@@ -657,7 +659,7 @@ public function getError(?string $field = null): string
         }
 
         $errors = array_filter($this->getErrors(), static fn ($key) => preg_match(
-            '/^' . str_replace('\.\*', '\..+', preg_quote($field, '/')) . '$/',
+            '/^' . str_replace(['\.\*', '\*\.'], ['\..+', '.+\.'], preg_quote($field, '/')) . '$/',
             $key
         ), ARRAY_FILTER_USE_KEY);
 

tests/system/Validation/ValidationTest.php

@@ -1098,6 +1098,12 @@ public function validationArrayDataCaseProvider(): iterable
                 ['foo' => ['boz']],
             ]],
         ];
+
+        yield 'leading-asterisk' => [
+            true,
+            ['*.foo' => 'required'],
+            [['foo' => 'bar']],
+        ];
     }
 
     /**
@@ -1324,4 +1330,17 @@ public function testNestedArrayThrowsException(): void
             'beneficiaries_accounts.account_2.purpose'       => 'The PURPOSE field must be at least 3 characters in length.',
         ], $this->validation->getErrors());
     }
+
+    public function testRuleWithLeadingAsterisk(): void
+    {
+        $data = [
+            ['foo' => 1],
+            ['foo' => null],
+        ];
+
+        $this->validation->setRules(['*.foo' => 'required'], ['1.foo' => ['required' => 'Required {field}']]);
+
+        $this->assertFalse($this->validation->run($data));
+        $this->assertSame('Required *.foo', $this->validation->getError('*.foo'));
+    }
 }

user_guide_src/source/changelogs/v4.2.2.rst

@@ -25,6 +25,7 @@ Changes
 *******
 
 - Fixed: ``BaseBuilder::increment()`` and ``BaseBuilder::decrement()`` do not reset the ``BaseBuilder`` state after a query.
+- Fixed: Validation of fields with a leading asterisk (wildcard).
 - Now ``CLIRequest::isCLI()`` always returns true.
 - Now ``IncommingRequest::isCLI()`` always returns false.