Testcase and tentative fix for #1237

rest_framework/renderers.py

@@ -346,6 +346,7 @@ class HTMLFormRenderer(BaseRenderer):
         request = renderer_context['request']
 
         template = loader.get_template(self.template)
+        data = None if data.empty else data
         context = RequestContext(request, {'form': data})
         return template.render(context)
 

rest_framework/serializers.py

@@ -340,6 +340,7 @@ class BaseSerializer(WritableField):
         """
         ret = self._dict_class()
         ret.fields = self._dict_class()
+        ret.empty = obj is None
 
         for field_name, field in self.fields.items():
             if field.read_only and obj is None:

rest_framework/tests/test_issue_1237.py

@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+# This is based on https://github.com/kevin-brown/django-rest-framework/compare/issue_1237.
+from __future__ import unicode_literals
+
+from django.test import TestCase
+from rest_framework.compat import patterns, url
+from rest_framework.generics import GenericAPIView
+from rest_framework.renderers import BrowsableAPIRenderer
+from rest_framework.response import Response
+from rest_framework.serializers import Serializer, HyperlinkedRelatedField
+from rest_framework.tests.models import Album
+
+
+class TestSerializer(Serializer):
+    field = HyperlinkedRelatedField(queryset=Album.objects, view_name="")
+
+
+class TestView(GenericAPIView):
+    renderer_classes = (BrowsableAPIRenderer, )
+    serializer_class = TestSerializer
+
+    def post(self, request, **kwargs):
+        return Response("text")
+
+
+urlpatterns = patterns('',
+    url(r"^view/(?P<pk>\d+)$", TestView.as_view(), name="view"),
+)
+
+
+class FailingTestCase(TestCase):
+    urls = 'rest_framework.tests.test_issue_1237'
+
+    def test_issue_1237(self):
+        album = Album(title="test")
+        album.save()
+
+        response = self.client.post("/view/{0}".format(album.pk))
+        self.assertEqual(200, response.status_code)