First stab at new view decorators

2 files changed, 186 insertions, 30 deletions

diff --git a/djangorestframework/decorators.py b/djangorestframework/decorators.py
index 814f321a..22bb8d3e 100644
--- a/djangorestframework/decorators.py
+++ b/djangorestframework/decorators.py
@@ -1,12 +1,68 @@
 from functools import wraps
-from django.http import Http404
 from django.utils.decorators import available_attrs
-from django.core.exceptions import PermissionDenied
-from djangorestframework import exceptions
-from djangorestframework import status
-from djangorestframework.response import Response
-from djangorestframework.request import Request
-from djangorestframework.settings import api_settings
+from djangorestframework.views import APIView
+
+
+class LazyViewCreator(object):
+
+    """
+    This class is responsible for dynamically creating an APIView subclass that
+    will wrap a function-based view. Instances of this class are created
+    by the function-based view decorators (below), and each decorator is
+    responsible for setting attributes on the instance that will eventually be
+    copied onto the final class-based view. The CBV gets created lazily the first
+    time it's needed, and then cached for future use.
+
+    This is done so that the ordering of stacked decorators is irrelevant.
+    """
+
+    def __init__(self):
+
+        # Each item in this dictionary will be copied onto the final
+        # class-based view that gets created when this object is called
+        self.final_view_attrs = {
+            'renderer_classes': APIView.renderer_classes,
+            'parser_classes': APIView.parser_classes,
+            'authentication_classes': APIView.authentication_classes,
+            'throttle_classes': APIView.throttle_classes,
+            'permission_classes': APIView.permission_classes,
+        }
+        self._cached_view = None
+
+    @property
+    def view(self):
+        """
+        Accessor for the dynamically created class-based view. This will
+        be created if necessary and cached for next time.
+        """
+
+        if self._cached_view is None:
+
+            class WrappedAPIView(APIView):
+                pass
+
+            for attr, value in self.final_view_attrs.items():
+                setattr(WrappedAPIView, attr, value)
+
+            self._cached_view = WrappedAPIView.as_view()
+
+        return self._cached_view
+
+    def __call__(self, *args, **kwargs):
+        """
+        This is the actual code that gets run per-request
+        """
+        return self.view(*args, **kwargs)
+
+    @staticmethod
+    def maybe_create(func):
+        """
+        If the argument is already an instance of LazyViewCreator,
+        just return it. Otherwise, create a new one.
+        """
+        if isinstance(func, LazyViewCreator):
+            return func
+        return LazyViewCreator()
 
 
 def api_view(allowed_methods):
@@ -19,35 +75,33 @@ def api_view(allowed_methods):
             # `Response` objects will have .request set automatically
             # APIException instances will be handled
     """
-    allowed_methods = [method.upper() for method in allowed_methods]
 
     def decorator(func):
-        @wraps(func, assigned=available_attrs(func))
-        def inner(request, *args, **kwargs):
-            try:
-
-                request = Request(request)
+        wrapper = LazyViewCreator.maybe_create(func)
 
-                if request.method not in allowed_methods:
-                    raise exceptions.MethodNotAllowed(request.method)
-
-                response = func(request, *args, **kwargs)
+        @wraps(func, assigned=available_attrs(func))
+        def handler(self, *args, **kwargs):
+            return func(*args, **kwargs)
 
-                if isinstance(response, Response):
-                    response.request = request
-                    if api_settings.FORMAT_SUFFIX_KWARG:
-                        response.format = kwargs.get(api_settings.FORMAT_SUFFIX_KWARG, None)
-                return response
+        for method in allowed_methods:
+            wrapper.final_view_attrs[method.lower()] = handler
 
-            except exceptions.APIException as exc:
-                return Response({'detail': exc.detail}, status=exc.status_code)
+        return wrapper
+    return decorator
 
-            except Http404 as exc:
-                return Response({'detail': 'Not found'},
-                                status=status.HTTP_404_NOT_FOUND)
 
-            except PermissionDenied as exc:
-                return Response({'detail': 'Permission denied'},
-                                status=status.HTTP_403_FORBIDDEN)
+def _create_attribute_setting_decorator(attribute):
+    def decorator(value):
+        def inner(func):
+            wrapper = LazyViewCreator.maybe_create(func)
+            wrapper.final_view_attrs[attribute] = value
+            return wrapper
         return inner
     return decorator
+
+
+renderer_classes = _create_attribute_setting_decorator('renderer_classes')
+parser_classes = _create_attribute_setting_decorator('parser_classes')
+authentication_classes = _create_attribute_setting_decorator('authentication_classes')
+throttle_classes = _create_attribute_setting_decorator('throttle_classes')
+permission_classes = _create_attribute_setting_decorator('permission_classes')
diff --git a/djangorestframework/tests/decorators.py b/djangorestframework/tests/decorators.py
new file mode 100644
index 00000000..0d3be8f3
--- /dev/null
+++ b/djangorestframework/tests/decorators.py
@@ -0,0 +1,102 @@
+from django.test import TestCase
+from djangorestframework.response import Response
+from djangorestframework.compat import RequestFactory
+from djangorestframework.renderers import JSONRenderer
+from djangorestframework.parsers import JSONParser
+from djangorestframework.authentication import BasicAuthentication
+from djangorestframework.throttling import SimpleRateThottle
+from djangorestframework.permissions import IsAuthenticated
+from djangorestframework.decorators import (
+    api_view,
+    renderer_classes,
+    parser_classes,
+    authentication_classes,
+    throttle_classes,
+    permission_classes,
+    LazyViewCreator
+)
+
+
+class DecoratorTestCase(TestCase):
+
+    def setUp(self):
+        self.factory = RequestFactory()
+
+    def test_wrap_view(self):
+
+        @api_view(['GET'])
+        def view(request):
+            return Response({})
+
+        self.assertTrue(isinstance(view, LazyViewCreator))
+
+    def test_calling_method(self):
+
+        @api_view(['GET'])
+        def view(request):
+            return Response({})
+
+        request = self.factory.get('/')
+        response = view(request)
+        self.assertEqual(response.status_code, 200)
+
+        request = self.factory.post('/')
+        response = view(request)
+        self.assertEqual(response.status_code, 405)
+
+    def test_renderer_classes(self):
+
+        @renderer_classes([JSONRenderer])
+        @api_view(['GET'])
+        def view(request):
+            return Response({})
+
+        request = self.factory.get('/')
+        response = view(request)
+        self.assertEqual(response.renderer_classes, [JSONRenderer])
+
+    def test_parser_classes(self):
+
+        @parser_classes([JSONParser])
+        @api_view(['GET'])
+        def view(request):
+            return Response({})
+
+        request = self.factory.get('/')
+        response = view(request)
+        self.assertEqual(response.request.parser_classes, [JSONParser])
+
+    def test_authentication_classes(self):
+
+        @authentication_classes([BasicAuthentication])
+        @api_view(['GET'])
+        def view(request):
+            return Response({})
+
+        request = self.factory.get('/')
+        response = view(request)
+        self.assertEqual(response.request.authentication_classes, [BasicAuthentication])
+
+# Doesn't look like these bits are working quite yet
+
+#    def test_throttle_classes(self):
+#
+#        @throttle_classes([SimpleRateThottle])
+#        @api_view(['GET'])
+#        def view(request):
+#            return Response({})
+#
+#        request = self.factory.get('/')
+#        response = view(request)
+#        self.assertEqual(response.request.throttle, [SimpleRateThottle])
+
+#    def test_permission_classes(self):
+
+#        @permission_classes([IsAuthenticated])
+#        @api_view(['GET'])
+#        def view(request):
+#            return Response({})
+
+#        request = self.factory.get('/')
+#        response = view(request)
+#        self.assertEqual(response.request.permission_classes, [IsAuthenticated])