Fixed #27688 -- Made messages' add_message() request check use ducktyping.

django/contrib/messages/api.py

@@ -1,6 +1,5 @@
 from django.contrib.messages import constants
 from django.contrib.messages.storage import default_storage
-from django.http import HttpRequest
 
 __all__ = (
     'add_message', 'get_messages',
@@ -18,16 +17,21 @@ def add_message(request, level, message, extra_tags='', fail_silently=False):
     """
     Attempts to add a message to the request using the 'messages' app.
     """
-    if not isinstance(request, HttpRequest):
-        raise TypeError("add_message() argument must be an HttpRequest object, "
-                        "not '%s'." % request.__class__.__name__)
-    if hasattr(request, '_messages'):
-        return request._messages.add(level, message, extra_tags)
-    if not fail_silently:
-        raise MessageFailure(
-            'You cannot add messages without installing '
-            'django.contrib.messages.middleware.MessageMiddleware'
-        )
+    try:
+        messages = request._messages
+    except AttributeError:
+        if not hasattr(request, 'META'):
+            raise TypeError(
+                "add_message() argument must be an HttpRequest object, not "
+                "'%s'." % request.__class__.__name__
+            )
+        if not fail_silently:
+            raise MessageFailure(
+                'You cannot add messages without installing '
+                'django.contrib.messages.middleware.MessageMiddleware'
+            )
+    else:
+        return messages.add(level, message, extra_tags)
 
 
 def get_messages(request):

tests/messages_tests/test_api.py

@@ -42,3 +42,24 @@ class ApiTests(SimpleTestCase):
     def test_middleware_missing_silently(self):
         messages.add_message(self.request, messages.DEBUG, 'some message', fail_silently=True)
         self.assertEqual(self.storage.store, [])
+
+
+class CustomRequest(object):
+    def __init__(self, request):
+        self._request = request
+
+    def __getattribute__(self, attr):
+        try:
+            return super(CustomRequest, self).__getattribute__(attr)
+        except AttributeError:
+            return getattr(self._request, attr)
+
+
+class CustomRequestApiTests(ApiTests):
+    """
+    add_message() should use ducktyping to allow request wrappers such as the
+    one in Django REST framework.
+    """
+    def setUp(self):
+        super(CustomRequestApiTests, self).setUp()
+        self.request = CustomRequest(self.request)