add default handling of Django ValidationError exceptions

rest_framework/views.py

@@ -6,6 +6,7 @@ from __future__ import unicode_literals
 import inspect
 import warnings
 
+from django.core.exceptions import ValidationError as DjangoValidationError
 from django.core.exceptions import PermissionDenied
 from django.http import Http404
 from django.utils import six
@@ -90,6 +91,12 @@ def exception_handler(exc, context):
 
         set_rollback()
         return Response(data, status=status.HTTP_403_FORBIDDEN)
+    elif isinstance(exc, DjangoValidationError):
+        msg = _('Validation error.')
+        data = {'detail': exc.messages}
+
+        set_rollback()
+        return Response(data, status=status.HTTP_400_BAD_REQUEST)
 
     # Note: Unhandled exceptions will raise a 500 error.
     return None

tests/test_views.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 import copy
 import sys
 
+from django.core.validators import validate_ipv4_address
 from django.test import TestCase
 
 from rest_framework import status
@@ -19,6 +20,8 @@ if sys.version_info[:2] >= (3, 4):
 else:
     JSON_ERROR = 'JSON parse error - No JSON object could be decoded'
 
+IPV4_VALIDATION_ERROR = ['Enter a valid IPv4 address.']
+
 
 class BasicView(APIView):
     def get(self, request, *args, **kwargs):
@@ -50,6 +53,18 @@ def error_view(request):
     raise Exception
 
 
+class ValidationErrorView(APIView):
+    def get(self, request, *args, **kwargs):
+        'raises a django ValidtionError by calling the ip4 validation function with a bad input'
+        validate_ipv4_address('a.b.c.d')
+
+
+@api_view(['GET'])
+def validation_error_view(request):
+    'raises a django ValidtionError by calling the ip4 validation function with a bad input'
+    validate_ipv4_address('a.b.c.d')
+
+
 def sanitise_json_error(error_dict):
     """
     Exact contents of JSON error messages depend on the installed version
@@ -148,3 +163,27 @@ class TestCustomExceptionHandler(TestCase):
         expected = 'Error!'
         self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
         self.assertEqual(response.data, expected)
+
+
+class TestDjangoValidationErrorHandlling(TestCase):
+    def test_class_based_validation_error_handling(self):
+        view = ValidationErrorView.as_view()
+
+        request = factory.get('/')
+        response = view(request)
+        expected = {
+            'detail': IPV4_VALIDATION_ERROR
+        }
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertEqual(response.data, expected)
+
+    def test_function_based_validation_error_handling(self):
+        view = validation_error_view
+
+        request = factory.get('/')
+        response = view(request)
+        expected = {
+            'detail': IPV4_VALIDATION_ERROR
+        }
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertEqual(response.data, expected)