Allow to specify attribute name in type class

docs/validation/working-with-the-validator.md

@@ -51,6 +51,33 @@ class SongData extends Data
 }
 ```
 
+### Defining attribute in type
+
+If you want to define attribute name in the type itself, you can implement the `HasValidationAttributeName` interface:
+
+```php
+class SongData extends Data
+{
+    public function __construct(
+        public Title $title,
+    ) {
+    }
+}
+
+class Title implements HasValidationAttributeName
+{
+    public function __construct(
+        public string $value,
+    ) {
+    }
+
+    public static function validationAttributeName(): string
+    {
+        return 'Song title';
+    }
+}
+```
+
 ## Overwriting other validation functionality
 
 Next to overwriting the validator, attributes and messages it is also possible to overwrite the following functionality.

src/Contracts/HasValidationAttributeName.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace Spatie\LaravelData\Contracts;
+
+interface HasValidationAttributeName
+{
+    public static function validationAttributeName(): string;
+}

src/Resolvers/DataValidationMessagesAndAttributesResolver.php

@@ -3,7 +3,9 @@
 namespace Spatie\LaravelData\Resolvers;
 
 use Illuminate\Support\Arr;
+use Spatie\LaravelData\Contracts\HasValidationAttributeName;
 use Spatie\LaravelData\Support\DataConfig;
+use Spatie\LaravelData\Support\Types\NamedType;
 use Spatie\LaravelData\Support\Validation\ValidationPath;
 
 class DataValidationMessagesAndAttributesResolver
@@ -62,6 +64,14 @@ public function execute(
 
                 continue;
             }
+
+            if ($dataProperty->type->type instanceof NamedType) {
+                $typeClass = $dataProperty->type->type->name;
+
+                if (is_a($typeClass, HasValidationAttributeName::class, true)) {
+                    $attributes[$propertyPath->get()] = app()->call([$typeClass, 'validationAttributeName']);
+                }
+            }
         }
 
         if (method_exists($class, 'messages')) {

tests/ValidationTest.php

@@ -40,6 +40,7 @@
 use Spatie\LaravelData\Attributes\Validation\StringType;
 use Spatie\LaravelData\Attributes\Validation\Unique;
 use Spatie\LaravelData\Attributes\WithoutValidation;
+use Spatie\LaravelData\Contracts\HasValidationAttributeName;
 use Spatie\LaravelData\Data;
 use Spatie\LaravelData\DataCollection;
 use Spatie\LaravelData\Mappers\SnakeCaseMapper;
@@ -1969,6 +1970,30 @@ public static function attributes(FakeInjectable $injectable): array
     );
 });
 
+it('can resolve validation attributes from type ', function () {
+    class Address implements HasValidationAttributeName {
+        public function __construct(
+            public string $value,
+        ) {
+        }
+
+        public static function validationAttributeName(): string
+        {
+            return 'Home address';
+        }
+    }
+
+    $data = new class () extends Data {
+        public Address $address;
+    };
+
+    DataValidationAsserter::for($data)
+        ->assertAttributes(
+            ['address' => 'Home address'],
+            payload: ['address' => new Address('123 Fake Street')],
+        );
+});
+
 it('can manually set the redirect url', function () {
     $data = new class () extends Data {
         public string $name;