More robust form rendering in the browsable API (#4181)

rest_framework/renderers.py

@@ -472,31 +472,37 @@ class BrowsableAPIRenderer(BaseRenderer):
                 return
 
             if existing_serializer is not None:
-                serializer = existing_serializer
+                try:
+                    return self.render_form_for_serializer(existing_serializer)
+                except TypeError:
+                    pass
+
+            if has_serializer:
+                if method in ('PUT', 'PATCH'):
+                    serializer = view.get_serializer(instance=instance, **kwargs)
+                else:
+                    serializer = view.get_serializer(**kwargs)
             else:
-                if has_serializer:
-                    if method in ('PUT', 'PATCH'):
-                        serializer = view.get_serializer(instance=instance, **kwargs)
-                    else:
-                        serializer = view.get_serializer(**kwargs)
+                # at this point we must have a serializer_class
+                if method in ('PUT', 'PATCH'):
+                    serializer = self._get_serializer(view.serializer_class, view,
+                                                      request, instance=instance, **kwargs)
                 else:
-                    # at this point we must have a serializer_class
-                    if method in ('PUT', 'PATCH'):
-                        serializer = self._get_serializer(view.serializer_class, view,
-                                                          request, instance=instance, **kwargs)
-                    else:
-                        serializer = self._get_serializer(view.serializer_class, view,
-                                                          request, **kwargs)
-
-            if hasattr(serializer, 'initial_data'):
-                serializer.is_valid()
-
-            form_renderer = self.form_renderer_class()
-            return form_renderer.render(
-                serializer.data,
-                self.accepted_media_type,
-                {'style': {'template_pack': 'rest_framework/horizontal'}}
-            )
+                    serializer = self._get_serializer(view.serializer_class, view,
+                                                      request, **kwargs)
+
+            return self.render_form_for_serializer(serializer)
+
+    def render_form_for_serializer(self, serializer):
+        if hasattr(serializer, 'initial_data'):
+            serializer.is_valid()
+
+        form_renderer = self.form_renderer_class()
+        return form_renderer.render(
+            serializer.data,
+            self.accepted_media_type,
+            {'style': {'template_pack': 'rest_framework/horizontal'}}
+        )
 
     def get_raw_data_form(self, data, view, method, request):
         """

tests/browsable_api/test_form_rendering.py

+from django.test import TestCase
+
+from rest_framework import generics, renderers, serializers, status
+from rest_framework.response import Response
+from rest_framework.test import APIRequestFactory
+from tests.models import BasicModel
+
+factory = APIRequestFactory()
+
+
+class BasicSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = BasicModel
+
+
+class ManyPostView(generics.GenericAPIView):
+    queryset = BasicModel.objects.all()
+    serializer_class = BasicSerializer
+    renderer_classes = (renderers.BrowsableAPIRenderer, renderers.JSONRenderer)
+
+    def post(self, request, *args, **kwargs):
+        serializer = self.get_serializer(self.get_queryset(), many=True)
+        return Response(serializer.data, status.HTTP_200_OK)
+
+
+class TestManyPostView(TestCase):
+    def setUp(self):
+        """
+        Create 3 BasicModel instances.
+        """
+        items = ['foo', 'bar', 'baz']
+        for item in items:
+            BasicModel(text=item).save()
+        self.objects = BasicModel.objects
+        self.data = [
+            {'id': obj.id, 'text': obj.text}
+            for obj in self.objects.all()
+        ]
+        self.view = ManyPostView.as_view()
+
+    def test_post_many_post_view(self):
+        """
+        POST request to a view that returns a list of objects should
+        still successfully return the browsable API with a rendered form.
+
+        Regression test for https://github.com/tomchristie/django-rest-framework/pull/3164
+        """
+        data = {}
+        request = factory.post('/', data, format='json')
+        with self.assertNumQueries(1):
+            response = self.view(request).render()
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertEqual(len(response.data), 3)