[5.x] Support custom validation rules for asset containers (#13459)

Author: duncanmcclean

src/Fields/Validator.php

@@ -122,7 +122,7 @@ public function attributes()
         }, collect())->all();
     }
 
-    private function parse($rule)
+    public function parse($rule)
     {
         if (is_string($rule) && Str::startsWith($rule, 'new ')) {
             return $this->parseClassBasedRule($rule);

src/Http/Controllers/CP/Assets/AssetsController.php

@@ -2,6 +2,7 @@
 
 namespace Statamic\Http\Controllers\CP\Assets;
 
+use Facades\Statamic\Fields\Validator as FieldValidator;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\Validator;
 use Illuminate\Validation\ValidationException;
@@ -81,8 +82,12 @@ public function store(Request $request)
         abort_unless($container->allowUploads(), 403);
         $this->authorize('store', [AssetContract::class, $container]);
 
+        $validationRules = collect($container->validationRules())
+            ->map(fn ($rule) => FieldValidator::parse($rule))
+            ->all();
+
         $request->validate([
-            'file' => array_merge(['file', new AllowedFile], $container->validationRules()),
+            'file' => array_merge(['file', new AllowedFile], $validationRules),
         ]);
 
         $file = $request->file('file');