[1.10.x] Fixed #26915 -- Fixed regression handling responses returned from view middleware.

Backport of 44a6b40280 from master

django/core/handlers/base.py

@@ -177,13 +177,14 @@ class BaseHandler(object):
         for middleware_method in self._view_middleware:
             response = middleware_method(request, callback, callback_args, callback_kwargs)
             if response:
-                return response
+                break
 
-        wrapped_callback = self.make_view_atomic(callback)
-        try:
-            response = wrapped_callback(request, *callback_args, **callback_kwargs)
-        except Exception as e:
-            response = self.process_exception_by_middleware(e, request)
+        if response is None:
+            wrapped_callback = self.make_view_atomic(callback)
+            try:
+                response = wrapped_callback(request, *callback_args, **callback_kwargs)
+            except Exception as e:
+                response = self.process_exception_by_middleware(e, request)
 
         # Complain if the view returned None (a common error).
         if response is None:

tests/middleware_exceptions/middleware.py

@@ -2,6 +2,7 @@ from __future__ import unicode_literals
 
 from django.http import Http404, HttpResponse
 from django.template import engines
+from django.template.response import TemplateResponse
 
 log = []
 
@@ -40,9 +41,15 @@ class ProcessViewNoneMiddleware(BaseMiddleware):
         return None
 
 
+class ProcessViewTemplateResponseMiddleware(BaseMiddleware):
+    def process_view(self, request, view_func, view_args, view_kwargs):
+        template = engines['django'].from_string('Processed view {{ view }}{% for m in mw %}\n{{ m }}{% endfor %}')
+        return TemplateResponse(request, template, {'mw': [self.__class__.__name__], 'view': view_func.__name__})
+
+
 class TemplateResponseMiddleware(BaseMiddleware):
     def process_template_response(self, request, response):
-        response.template_name = engines['django'].from_string('template-response middleware')
+        response.context_data['mw'].append(self.__class__.__name__)
         return response
 
 

tests/middleware_exceptions/test_legacy.py

@@ -56,12 +56,25 @@ class ViewMiddleware(TestMiddleware):
         return HttpResponse('View Middleware')
 
 
+class TemplateResponseViewMiddleware(TestMiddleware):
+    def process_view(self, request, view_func, view_args, view_kwargs):
+        super(TemplateResponseViewMiddleware, self).process_view(request, view_func, view_args, view_kwargs)
+        template = engines['django'].from_string('TemplateResponse View Middleware')
+        return TemplateResponse(request, template)
+
+
 class ResponseMiddleware(TestMiddleware):
     def process_response(self, request, response):
         super(ResponseMiddleware, self).process_response(request, response)
         return HttpResponse('Response Middleware')
 
 
+class ContentAccessingResponseMiddleware(TestMiddleware):
+    def process_response(self, request, response):
+        super(ContentAccessingResponseMiddleware, self).process_response(request, response)
+        return HttpResponse('Content-accessing Response Middleware: %d' % len(response.content))
+
+
 class TemplateResponseMiddleware(TestMiddleware):
     def process_template_response(self, request, response):
         super(TemplateResponseMiddleware, self).process_template_response(request, response)
@@ -512,6 +525,30 @@ class MiddlewareTests(BaseMiddlewareExceptionTest):
         # Check that the right middleware methods have been invoked
         self.assert_middleware_usage(middleware, True, True, True, True, False)
 
+    def test_templateresponse_from_process_view_rendered(self):
+        view_middleware = TemplateResponseViewMiddleware()
+        # ContentAccessingResponseMiddleware tries to access response.content
+        # in its process_response().
+        post_middleware = ContentAccessingResponseMiddleware()
+        self._add_middleware(view_middleware)
+        self._add_middleware(post_middleware)
+        self.assert_exceptions_handled('/middleware_exceptions/view/', [])
+        self.assert_middleware_usage(view_middleware, True, True, True, True, False)
+        self.assert_middleware_usage(post_middleware, True, True, True, True, False)
+
+    def test_templateresponse_from_process_view_passed_to_template_response_middleware(self):
+        """
+        TemplateResponses returned from process_view() should be passed to any
+        process_template_response().
+        """
+        view_middleware = TemplateResponseViewMiddleware()
+        resp_middleware = TemplateResponseMiddleware()
+        self._add_middleware(view_middleware)
+        self._add_middleware(resp_middleware)
+        self.assert_exceptions_handled('/middleware_exceptions/view/', [])
+        self.assert_middleware_usage(view_middleware, True, True, True, True, False)
+        self.assert_middleware_usage(resp_middleware, True, True, True, True, False)
+
 
 class BadMiddlewareTests(BaseMiddlewareExceptionTest):
 

tests/middleware_exceptions/tests.py

@@ -22,10 +22,40 @@ class MiddlewareTests(SimpleTestCase):
         response = self.client.get('/middleware_exceptions/view/')
         self.assertEqual(response.content, b'Processed view normal_view')
 
+    @override_settings(MIDDLEWARE=[
+        'middleware_exceptions.middleware.ProcessViewTemplateResponseMiddleware',
+        'middleware_exceptions.middleware.LogMiddleware',
+    ])
+    def test_templateresponse_from_process_view_rendered(self):
+        """
+        TemplateResponses returned from process_view() must be rendered before
+        being passed to any middleware that tries to access response.content,
+        such as middleware_exceptions.middleware.LogMiddleware.
+        """
+        response = self.client.get('/middleware_exceptions/view/')
+        self.assertEqual(response.content, b'Processed view normal_view\nProcessViewTemplateResponseMiddleware')
+
+    @override_settings(MIDDLEWARE=[
+        'middleware_exceptions.middleware.ProcessViewTemplateResponseMiddleware',
+        'middleware_exceptions.middleware.TemplateResponseMiddleware',
+    ])
+    def test_templateresponse_from_process_view_passed_to_process_template_response(self):
+        """
+        TemplateResponses returned from process_view() should be passed to any
+        template response middleware.
+        """
+        response = self.client.get('/middleware_exceptions/view/')
+        expected_lines = [
+            b'Processed view normal_view',
+            b'ProcessViewTemplateResponseMiddleware',
+            b'TemplateResponseMiddleware',
+        ]
+        self.assertEqual(response.content, b'\n'.join(expected_lines))
+
     @override_settings(MIDDLEWARE=['middleware_exceptions.middleware.TemplateResponseMiddleware'])
     def test_process_template_response(self):
         response = self.client.get('/middleware_exceptions/template_response/')
-        self.assertEqual(response.content, b'template-response middleware')
+        self.assertEqual(response.content, b'template_response OK\nTemplateResponseMiddleware')
 
     @override_settings(MIDDLEWARE=['middleware_exceptions.middleware.LogMiddleware'])
     def test_view_exception_converted_before_middleware(self):

tests/middleware_exceptions/views.py

@@ -9,8 +9,8 @@ def normal_view(request):
 
 
 def template_response(request):
-    template = engines['django'].from_string('OK')
-    return TemplateResponse(request, template)
+    template = engines['django'].from_string('template_response OK{% for m in mw %}\n{{ m }}{% endfor %}')
+    return TemplateResponse(request, template, context={'mw': []})
 
 
 def template_response_error(request):