Update docs

README.md

@@ -122,7 +122,46 @@ If you have some validation rules which depends of payload data, then you can ha
 
 ### Handle validation errors
 
-TODO
+If validated data is invalid, library will throw exception which wil contain validation errors and request object.
+
+But if you don't want to handle it via `kernel.exception` listener, you have several options.
+
+First is to use your controller action to handle errors:
+
+```php
+
+public function registerUserAction(RegisterUserRequest $request, ConstraintViolationList $errors)
+{
+    if (0 !== count($errors)) {
+        // handle errors
+    }
+}
+
+```
+
+But this not so handy and will break DRY if you just need to return common error response. Thats why
+library provide you `ErrorResponseProvider` interface. You can impllement it in you request object and move this
+code to `getErrorResponse` method:
+
+```php
+public function getErrorResponse(ConstraintViolationListInterface $errors)
+{
+    return new JsonResponse([
+        'message' => 'Please check your data',
+        'errors' => array_map(function (ConstraintViolation $violation) {
+
+            return [
+                'path' => $violation->getPropertyPath(),
+                'message' => $violation->getMessage()
+            ];
+        }, iterator_to_array($errors))
+    ], 400);
+}
+```
+
+## More examples
+
+If you still not sure is it useful for you, please see `examples` directory for more use cases.
 
 ## Contribution
 

examples/Request/ResponseProvidingRequest.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace Fesor\RequestObject\Examples\Request;
+
+use Fesor\RequestObject\ErrorResponseProvider;
+use Fesor\RequestObject\RequestObject;
+use Symfony\Component\HttpFoundation\JsonResponse;
+use \Symfony\Component\Validator\Constraints as Assert;
+use Symfony\Component\Validator\ConstraintViolation;
+use Symfony\Component\Validator\ConstraintViolationListInterface;
+
+class ResponseProvidingRequest extends RequestObject implements ErrorResponseProvider
+{
+    public function rules()
+    {
+        return new Assert\Collection([
+            'test' => new Assert\NotBlank()
+        ]);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function getErrorResponse(ConstraintViolationListInterface $errors)
+    {
+        return new JsonResponse([
+            'message' => 'Please check your data',
+            'errors' => array_map(function (ConstraintViolation $violation) {
+                return [
+                    'path' => $violation->getPropertyPath(),
+                    'message' => $violation->getMessage()
+                ];
+            }, iterator_to_array($errors))
+        ], 400);
+    }
+}