update decorator to not create decorated functions per request

rest_framework_condition/decorators.py

@@ -1,36 +1,90 @@
 import functools
-from django.views.decorators.http import condition as django_condition
+import warnings
 
+from calendar import timegm
 
-def condition(etag_func=None, last_modified_func=None):
+from django.utils.cache import get_conditional_response
+from django.utils.http import http_date, quote_etag
+
+
+def condition(etag_func=None, last_modified_func=None, use_self=False):
     """
-    Decorator to support conditional retrieval (or change)
-    for a Django Rest Framework's ViewSet.
+    Decorator to support conditional retrieval (or change) for a Django Rest
+    Framework's ViewSet.
+
+    This decorator emulates Django's original decorator by wrapping the
+    underlying functionality where possible but handles the Django Rest
+    Framework request object.
 
-    It calls Django's original decorator but pass correct request object to it.
-    Django's original decorator doesn't work with DRF request object.
+    See: django.views.decorators.http.condition
     """
+
+    if not use_self:
+        warnings.warn(
+            'The etag_func and last_modified_func should accept a "self" '
+            'argument which matches how Django Rest Framework calls '
+            'view/viewset methods.\n\n'
+            'After updating the handlers pass "use_self" to the condition '
+            'decorator to enable the future functionality and silence this '
+            'warning.',
+            DeprecationWarning)
+
     def decorator(func):
         @functools.wraps(func)
-        def wrapper(obj_self, request, *args, **kwargs):
-            drf_request = request
-            wsgi_request = request._request
+        def wrapper(self, request, *args, **kwargs):
+            if etag_func:
+                if use_self:
+                    etag = etag_func(self, request, *args, **kwargs)
+                else:
+                    etag = etag_func(request, *args, **kwargs)
+
+                # The value from etag_func() could be quoted or unquoted.
+                if etag:
+                    etag = quote_etag(etag)
+            else:
+                etag = None
+
+            if last_modified_func:
+                if use_self:
+                    last_modified = last_modified_func(
+                        self, request, *args, **kwargs)
+                else:
+                    last_modified = last_modified_func(
+                        request, *args, **kwargs)
+
+                if last_modified:
+                    last_modified = timegm(last_modified.utctimetuple())
+            else:
+                last_modified = None
+
+            # pass the wrapped WSGI request for Django
+            response = get_conditional_response(
+                request._request,
+                etag=etag,
+                last_modified=last_modified,
+            )
+
+            if response is None:
+                response = func(self, request, *args, **kwargs)
+
+            # Set relevant headers on the response if they don't already exist
+            # and if the request method is safe.
+            if request.method in ('GET', 'HEAD'):
+                if last_modified and not response.has_header('Last-Modified'):
+                    response['Last-Modified'] = http_date(last_modified)
+                if etag:
+                    response.setdefault('ETag', etag)
 
-            def patched_viewset_method(*_args, **_kwargs):
-                """Call original viewset method with correct type of request"""
-                return func(obj_self, drf_request, *args, **kwargs)
+            return response
 
-            django_decorator = django_condition(etag_func, last_modified_func)
-            decorated_viewset_method = django_decorator(patched_viewset_method)
-            return decorated_viewset_method(wsgi_request, *args, **kwargs)
         return wrapper
     return decorator
 
 
 # Shortcut decorators for common cases based on ETag or Last-Modified only
-def etag(etag_func):
-    return condition(etag_func=etag_func)
+def etag(etag_func, use_self=False):
+    return condition(etag_func=etag_func, use_self=use_self)
 
 
-def last_modified(last_modified_func):
-    return condition(last_modified_func=last_modified_func)
+def last_modified(last_modified_func, use_self=False):
+    return condition(last_modified_func=last_modified_func, use_self=use_self)

tests/test_decorators.py

@@ -1,4 +1,5 @@
 import calendar
+import json
 from datetime import datetime
 
 from django.urls import reverse
@@ -209,3 +210,33 @@ def test_etag_has_access_to_kwargs_from_view(self):
         assert response.status_code == status.HTTP_200_OK
         assert response['ETag'] == '"hash-42"'
         assert response.data == {'data': 'etag', 'pk': '42'}
+
+
+class TestDecoratorMatchesBuiltin(APITestCase):
+    def check_responses(self, builtin_url, api_url):
+        builtin_response = self.client.get(builtin_url)
+        api_response = self.client.get(api_url)
+
+        assert builtin_response.status_code == api_response.status_code
+        assert json.loads(builtin_response.content) == api_response.data
+
+        # Check the headers added, but DRF is allowed to add additional
+        # headers, and the content length may differ.
+        for key in builtin_response._headers:
+            if key.lower() != 'content-length':
+                assert builtin_response[key] == api_response[key]
+
+    def test_etag(self):
+        self.check_responses(
+            builtin_url=reverse('builtin-view-etag'),
+            api_url=reverse('api-view-etag'))
+
+    def test_etag_with_kwargs(self):
+        self.check_responses(
+            builtin_url=reverse('builtin-view-etag-kwargs', args=[42]),
+            api_url=reverse('etag-kwargs-detail', args=[42]))
+
+    def test_last_modified(self):
+        self.check_responses(
+            builtin_url=reverse('builtin-view-last-modified'),
+            api_url=reverse('api-view-last-modified'))

tests/urls.py

@@ -2,6 +2,9 @@
 from rest_framework.routers import DefaultRouter
 
 from tests.views import (
+    builtin_etag_kwargs_view,
+    builtin_etag_view,
+    builtin_last_modified_view,
     ETagApiView,
     EtagFromKwargsViewSet,
     EtagViewSet,
@@ -20,15 +23,26 @@
 
 urlpatterns = [
     path(
-        "^api-view/no-condition/$",
+        "api-view/no-condition/",
         NoConditionApiView.as_view(),
         name="api-view-no-condition",
     ),
     path(
-        "^api-view/last-modified/$",
+        "api-view/last-modified/",
         LastModifiedApiView.as_view(),
         name="api-view-last-modified",
     ),
-    path("^api-view/etag/$", ETagApiView.as_view(), name="api-view-etag"),
-    path("^view-set/", include(router.urls)),
+    path("api-view/etag/", ETagApiView.as_view(), name="api-view-etag"),
+    path(
+        "builtin/last-modified/",
+        builtin_last_modified_view,
+        name="builtin-view-last-modified"
+    ),
+    path("builtin/etag/", builtin_etag_view, name="builtin-view-etag"),
+    path(
+        "builtin/etag/<pk>/",
+        builtin_etag_kwargs_view,
+        name="builtin-view-etag-kwargs",
+    ),
+    path("view-set/", include(router.urls)),
 ]

tests/views.py

@@ -1,36 +1,57 @@
 from datetime import datetime
 
+from django.http import JsonResponse
 from rest_framework import views, viewsets
 from rest_framework.response import Response
 
+from django.views.decorators.http import (
+    etag as builtin_etag,
+    last_modified as builtin_last_modified,
+)
 from rest_framework_condition import etag, last_modified
 
 
-def my_last_modified(request, *args, **kwargs):
+def my_last_modified(self, request, *args, **kwargs):
     return datetime(2019, 1, 1)
 
 
-def my_etag(request, *args, **kwargs):
+def my_etag(self, request, *args, **kwargs):
     return 'hash123'
 
 
-def etag_from_kwargs(request, *args, **kwargs):
+def etag_from_kwargs(self, request, *args, **kwargs):
     return 'hash-{}'.format(kwargs['pk'])
 
 
+@builtin_last_modified(lambda request: my_last_modified(None, request))
+def builtin_last_modified_view(request):
+    return JsonResponse({'data': '2019'})
+
+
+@builtin_etag(lambda request: my_etag(None, request))
+def builtin_etag_view(request):
+    return JsonResponse({'data': 'etag'})
+
+
+@builtin_etag(
+    lambda request, **kwargs: etag_from_kwargs(None, request, **kwargs))
+def builtin_etag_kwargs_view(request, pk):
+    return JsonResponse({'data': 'etag', 'pk': pk})
+
+
 class NoConditionApiView(views.APIView):
     def get(self, request):
         return Response({'data': 'no-condition'})
 
 
 class LastModifiedApiView(views.APIView):
-    @last_modified(my_last_modified)
+    @last_modified(my_last_modified, use_self=True)
     def get(self, request):
         return Response({'data': '2019'})
 
 
 class ETagApiView(views.APIView):
-    @etag(my_etag)
+    @etag(my_etag, use_self=True)
     def get(self, request):
         return Response({'data': 'etag'})
 
@@ -44,26 +65,26 @@ def retrieve(self, request, pk=None):
 
 
 class LastModifiedViewSet(viewsets.ViewSet):
-    @last_modified(my_last_modified)
+    @last_modified(my_last_modified, use_self=True)
     def list(self, request):
         return Response({'data': '2019'})
 
-    @last_modified(my_last_modified)
+    @last_modified(my_last_modified, use_self=True)
     def retrieve(self, request, pk=None):
         return Response({'data': '2019', 'pk': pk})
 
 
 class EtagViewSet(viewsets.ViewSet):
-    @etag(my_etag)
+    @etag(my_etag, use_self=True)
     def list(self, request):
         return Response({'data': 'etag'})
 
-    @etag(my_etag)
+    @etag(my_etag, use_self=True)
     def retrieve(self, request, pk=None):
         return Response({'data': 'etag', 'pk': pk})
 
 
 class EtagFromKwargsViewSet(viewsets.ViewSet):
-    @etag(etag_from_kwargs)
+    @etag(etag_from_kwargs, use_self=True)
     def retrieve(self, request, pk=None):
         return Response({'data': 'etag', 'pk': pk})

tox.ini

@@ -12,4 +12,4 @@ deps =
     pytest-cov
 commands =
     # NOTE: you can run any command line tool here - not just tests
-    pytest --cov=rest_framework_condition/
+    pytest --cov=rest_framework_condition/ {posargs}