Fixed #16418 -- Made generic views work with ModelForms

Generic views assumed any object's _meta will be model Options. This
is not true for ModelForms for example. Took isinstance(obj, Model)
in use instead.

django/views/generic/detail.py

 from __future__ import unicode_literals
 
 from django.core.exceptions import ImproperlyConfigured, ObjectDoesNotExist
+from django.db import models
 from django.http import Http404
 from django.utils.translation import ugettext as _
 from django.views.generic.base import TemplateResponseMixin, ContextMixin, View
@@ -81,7 +82,7 @@ class SingleObjectMixin(ContextMixin):
         """
         if self.context_object_name:
             return self.context_object_name
-        elif hasattr(obj, '_meta'):
+        elif isinstance(obj, models.Model):
             return obj._meta.object_name.lower()
         else:
             return None
@@ -128,13 +129,13 @@ class SingleObjectTemplateResponseMixin(TemplateResponseMixin):
 
         # The least-specific option is the default <app>/<model>_detail.html;
         # only use this if the object in question is a model.
-        if hasattr(self.object, '_meta'):
+        if isinstance(self.object, models.Model):
             names.append("%s/%s%s.html" % (
                 self.object._meta.app_label,
                 self.object._meta.object_name.lower(),
                 self.template_name_suffix
             ))
-        elif hasattr(self, 'model') and hasattr(self.model, '_meta'):
+        elif hasattr(self, 'model') and self.model is not None and issubclass(self.model, models.Model):
             names.append("%s/%s%s.html" % (
                 self.model._meta.app_label,
                 self.model._meta.object_name.lower(),

tests/regressiontests/generic_views/detail.py

@@ -92,3 +92,8 @@ class DetailViewTest(TestCase):
 
     def test_invalid_queryset(self):
         self.assertRaises(ImproperlyConfigured, self.client.get, '/detail/author/invalid/qs/')
+
+    def test_non_model_object_with_meta(self):
+        res = self.client.get('/detail/nonmodel/1/')
+        self.assertEqual(res.status_code, 200)
+        self.assertEqual(res.context['object'].id, "non_model_1")

tests/regressiontests/generic_views/urls.py

@@ -53,6 +53,8 @@ urlpatterns = patterns('',
         views.AuthorDetail.as_view()),
     (r'^detail/author/invalid/qs/$',
         views.AuthorDetail.as_view(queryset=None)),
+    (r'^detail/nonmodel/1/$',
+        views.NonModelDetail.as_view()),
 
     # Create/UpdateView
     (r'^edit/artists/create/$',

tests/regressiontests/generic_views/views.py

@@ -226,3 +226,18 @@ class BookSigningTodayArchive(BookSigningConfig, generic.TodayArchiveView):
 
 class BookSigningDetail(BookSigningConfig, generic.DateDetailView):
     context_object_name = 'book'
+
+
+class NonModel(object):
+    id = "non_model_1"
+
+    _meta = None
+
+
+class NonModelDetail(generic.DetailView):
+
+    template_name = 'generic_views/detail.html'
+    model = NonModel
+
+    def get_object(self, queryset=None):
+        return NonModel()