doc: update validation exception code to 422 (#1206)

Author: ahmed-bhs

core/errors.md

@@ -79,6 +79,9 @@ api_platform:
         ApiPlatform\Core\Exception\FilterValidationException: 400
         Doctrine\ORM\OptimisticLockException: 409
 
+        # Validation exception
+        ApiPlatform\Core\Bridge\Symfony\Validator\Exception\ValidationException: !php/const Symfony\Component\HttpFoundation\Response::HTTP_UNPROCESSABLE_ENTITY
+
         # Custom mapping
         App\Exception\ProductNotFoundException: 404 # Here is the handler for our custom exception
 ```

core/graphql.md

@@ -1292,7 +1292,7 @@ It's because a built-in [custom exception normalizer](#custom-exception-normaliz
 If you are in `dev` mode, more entries will be added in the response: `debugMessage` (containing the actual exception message, for instance in the case of a `LogicException`) and `trace` (the formatted exception trace).
 
 For some specific exceptions, built-in [custom exception normalizers](#custom-exception-normalizer) are also used to add more information.
-It's the case for a `HttpException` for which the `status` entry will be added under `extensions` and for a `ValidationException` for which `status` (always 400) and `violations` entries will be added.
+It's the case for a `HttpException` for which the `status` entry will be added under `extensions` and for a `ValidationException` for which `status` (by default 422) and `violations` entries will be added.
 
 #### Custom Exception Normalizer
 

core/validation.md

@@ -102,7 +102,7 @@ final class MinimalPropertiesValidator extends ConstraintValidator
 }
 ```
 
-If the data submitted by the client is invalid, the HTTP status code will be set to `400 Bad Request` and the response's
+If the data submitted by the client is invalid, the HTTP status code will be set to `422 Unprocessable Entity` and the response's
 body will contain the list of violations serialized in a format compliant with the requested one. For instance, a validation
 error will look like the following if the requested format is JSON-LD (the default):
 

distribution/testing.md

@@ -152,7 +152,7 @@ class BooksTest extends ApiTestCase
             'isbn' => 'invalid',
         ]]);
 
-        $this->assertResponseStatusCodeSame(400);
+        $this->assertResponseStatusCodeSame(422);
         $this->assertResponseHeaderSame('content-type', 'application/ld+json; charset=utf-8');
 
         $this->assertJsonContains([