fix: validation custom error with asterisk field

system/Validation/Validation.php

@@ -168,7 +168,7 @@ public function run(?array $data = null, ?string $group = null, ?string $dbGroup
             if (strpos($field, '*') !== false) {
                 // Process multiple fields
                 foreach ($values as $dotField => $value) {
-                    $this->processRules($dotField, $setup['label'] ?? $field, $value, $rules, $data);
+                    $this->processRules($dotField, $setup['label'] ?? $field, $value, $rules, $data, $field);
                 }
             } else {
                 // Process single field
@@ -203,7 +203,7 @@ public function check($value, string $rule, array $errors = []): bool
      * @param array|null   $rules
      * @param array        $data
      */
-    protected function processRules(string $field, ?string $label, $value, $rules = null, ?array $data = null): bool
+    protected function processRules(string $field, ?string $label, $value, $rules = null, ?array $data = null, ?string $originalField = null): bool
     {
         if ($data === null) {
             throw new InvalidArgumentException('You must supply the parameter: data.');
@@ -333,7 +333,8 @@ protected function processRules(string $field, ?string $label, $value, $rules =
                     $field,
                     $label,
                     $param,
-                    (string) $value
+                    (string) $value,
+                    $originalField
                 );
 
                 return false;
@@ -706,13 +707,15 @@ public function setError(string $field, string $error): ValidationInterface
      *
      * @param string|null $value The value that caused the validation to fail.
      */
-    protected function getErrorMessage(string $rule, string $field, ?string $label = null, ?string $param = null, ?string $value = null): string
+    protected function getErrorMessage(string $rule, string $field, ?string $label = null, ?string $param = null, ?string $value = null, ?string $originalField = null): string
     {
         $param ??= '';
 
         // Check if custom message has been defined by user
         if (isset($this->customErrors[$field][$rule])) {
             $message = lang($this->customErrors[$field][$rule]);
+        } elseif (null !== $originalField && isset($this->customErrors[$originalField][$rule])) {
+            $message = lang($this->customErrors[$originalField][$rule]);
         } else {
             // Try to grab a localized version of the message...
             // lang() will return the rule name back if not found,

tests/system/Validation/StrictRules/ValidationTest.php

@@ -359,6 +359,28 @@ public function testRunGroupWithCustomErrorMessage(): void
         ], $this->validation->getErrors());
     }
 
+    /**
+     * @see https://github.com/codeigniter4/CodeIgniter4/issues/6245
+     */
+    public function testRunWithCustomErrorsAndAsteriskField(): void
+    {
+        $data = [
+            'foo' => [
+                ['bar' => null],
+                ['bar' => null],
+            ],
+        ];
+        $this->validation->setRules(
+            ['foo.*.bar' => ['label' => 'foo bar', 'rules' => 'required']],
+            ['foo.*.bar' => ['required' => 'Required']]
+        );
+        $this->validation->run($data);
+        $this->assertSame([
+            'foo.0.bar' => 'Required',
+            'foo.1.bar' => 'Required',
+        ], $this->validation->getErrors());
+    }
+
     /**
      * @dataProvider rulesSetupProvider
      *