From 8ee63e90b87989c5c22d92e3440ec3e689ca8bfd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alejandro=20R=2E=20Sede=C3=B1o?= <asedeno@mit.edu>
Date: Tue, 23 Feb 2016 13:01:46 -0500
Subject: [PATCH] Collect serialziers to try when rendering the Browsable API

The first one should work, if it doesn't because of Issue #2918, then
the second one should work. If no collected serializer worked, raise
the exception generated by the last one.
---
 rest_framework/renderers.py | 52 +++++++++++++++++++++----------------
 1 file changed, 30 insertions(+), 22 deletions(-)

diff --git a/rest_framework/renderers.py b/rest_framework/renderers.py
index 024f0eb8b..9740a0409 100644
--- a/rest_framework/renderers.py
+++ b/rest_framework/renderers.py
@@ -473,32 +473,40 @@ class BrowsableAPIRenderer(BaseRenderer):
             ):
                 return
 
+            serializers = []
             if existing_serializer is not None:
-                serializer = existing_serializer
-            else:
-                if has_serializer:
-                    if method in ('PUT', 'PATCH'):
-                        serializer = view.get_serializer(instance=instance, **kwargs)
-                    else:
-                        serializer = view.get_serializer(**kwargs)
+                serializers.append(existing_serializer)
+
+            if has_serializer:
+                if method in ('PUT', 'PATCH'):
+                    serializers.append(view.get_serializer(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)
+                    serializers.append(view.get_serializer(**kwargs))
+            else:
+                # at this point we must have a serializer_class
+                if method in ('PUT', 'PATCH'):
+                    serializers.append(self._get_serializer(view.serializer_class, view,
+                                                            request, instance=instance, **kwargs))
+                else:
+                    serializers.append(self._get_serializer(view.serializer_class, view,
+                                                            request, **kwargs))
 
-            if hasattr(serializer, 'initial_data'):
-                serializer.is_valid()
+            for serializer in serializers:
+                try:
+                    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'}}
-            )
+                    form_renderer = self.form_renderer_class()
+                    return form_renderer.render(
+                        serializer.data,
+                        self.accepted_media_type,
+                        {'style': {'template_pack': 'rest_framework/horizontal'}}
+                    )
+                except TypeError:
+                    pass
+            # If none of the rendering attempts succeeded, raise the TypeError generated by the last
+            # attempt.
+            raise
 
     def get_raw_data_form(self, data, view, method, request):
         """