Added handling of validation errors in PUT-as-create.

Fixes #1035.

rest_framework/mixins.py

@@ -6,6 +6,7 @@ which allows mixin classes to be composed in interesting ways.
 """
 from __future__ import unicode_literals
 
+from django.core.exceptions import ValidationError
 from django.http import Http404
 from rest_framework import status
 from rest_framework.response import Response
@@ -127,7 +128,12 @@ class UpdateModelMixin(object):
                                          files=request.FILES, partial=partial)
 
         if serializer.is_valid():
-            self.pre_save(serializer.object)
+            try:
+                self.pre_save(serializer.object)
+            except ValidationError as err:
+                # full_clean on model instance may be called in pre_save, so we
+                # have to handle eventual errors.
+                return Response(err.message_dict, status=status.HTTP_400_BAD_REQUEST)
             self.object = serializer.save(**save_kwargs)
             self.post_save(self.object, created=created)
             return Response(serializer.data, status=success_status_code)

rest_framework/tests/test_generics.py

@@ -23,6 +23,10 @@ class InstanceView(generics.RetrieveUpdateDestroyAPIView):
     """
     model = BasicModel
 
+    def get_queryset(self):
+        queryset = super(InstanceView, self).get_queryset()
+        return queryset.exclude(text='filtered out')
+
 
 class SlugSerializer(serializers.ModelSerializer):
     slug = serializers.Field()  # read only
@@ -160,10 +164,10 @@ class TestInstanceView(TestCase):
         """
         Create 3 BasicModel intances.
         """
-        items = ['foo', 'bar', 'baz']
+        items = ['foo', 'bar', 'baz', 'filtered out']
         for item in items:
             BasicModel(text=item).save()
-        self.objects = BasicModel.objects
+        self.objects = BasicModel.objects.exclude(text='filtered out')
         self.data = [
             {'id': obj.id, 'text': obj.text}
             for obj in self.objects.all()
@@ -352,6 +356,17 @@ class TestInstanceView(TestCase):
         updated = self.objects.get(id=1)
         self.assertEqual(updated.text, 'foobar')
 
+    def test_put_to_filtered_out_instance(self):
+        """
+        PUT requests to an URL of instance which is filtered out should not be
+        able to create new objects.
+        """
+        data = {'text': 'foo'}
+        filtered_out_pk = BasicModel.objects.filter(text='filtered out')[0].pk
+        request = factory.put('/{0}'.format(filtered_out_pk), data, format='json')
+        response = self.view(request, pk=filtered_out_pk).render()
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+
     def test_put_as_create_on_id_based_url(self):
         """
         PUT requests to RetrieveUpdateDestroyAPIView should create an object