Async view implementation

.github/workflows/main.yml

@@ -12,6 +12,7 @@ jobs:
     runs-on: ubuntu-20.04
 
     strategy:
+      fail-fast: false
       matrix:
         python-version:
         - '3.6'

docs/api-guide/views.md

@@ -217,6 +217,22 @@ You may pass `None` in order to exclude the view from schema generation.
     def view(request):
         return Response({"message": "Will not appear in schema!"})
 
+# Async Views
+
+When using Django 4.1 and above, REST framework allows you to work with async class and function based views.
+
+For class based views, all handler methods must be async, otherwise Django will raise an exception. For function based views, the function itself must be async.
+
+For example:
+
+    class AsyncView(APIView):
+        async def get(self, request):
+            return Response({"message": "This is an async class based view."})
+
+
+    @api_view(['GET'])
+    async def async_view(request):
+        return Response({"message": "This is an async function based view."})
 
 [cite]: https://reinout.vanrees.org/weblog/2011/08/24/class-based-views-usage.html
 [cite2]: http://www.boredomandlaziness.org/2012/05/djangos-cbvs-are-not-mistake-but.html

rest_framework/compat.py

@@ -41,6 +41,17 @@ except ImportError:
     uritemplate = None
 
 
+# async_to_sync is required for async view support
+if django.VERSION >= (4, 1):
+    from asgiref.sync import async_to_sync, iscoroutinefunction, sync_to_async
+else:
+    async_to_sync = None
+    sync_to_async = None
+
+    def iscoroutinefunction(func):
+        return False
+
+
 # coreschema is optional
 try:
     import coreschema

rest_framework/decorators.py

@@ -10,6 +10,7 @@ import types
 
 from django.forms.utils import pretty_name
 
+from rest_framework.compat import iscoroutinefunction
 from rest_framework.views import APIView
 
 
@@ -46,8 +47,12 @@ def api_view(http_method_names=None):
         allowed_methods = set(http_method_names) | {'options'}
         WrappedAPIView.http_method_names = [method.lower() for method in allowed_methods]
 
-        def handler(self, *args, **kwargs):
-            return func(*args, **kwargs)
+        if iscoroutinefunction(func):
+            async def handler(self, *args, **kwargs):
+                return await func(*args, **kwargs)
+        else:
+            def handler(self, *args, **kwargs):
+                return func(*args, **kwargs)
 
         for method in http_method_names:
             setattr(WrappedAPIView, method.lower(), handler)

rest_framework/test.py

@@ -11,6 +11,10 @@ from django.test import override_settings, testcases
 from django.test.client import Client as DjangoClient
 from django.test.client import ClientHandler
 from django.test.client import RequestFactory as DjangoRequestFactory
+
+if django.VERSION >= (4, 1):
+    from django.test.client import AsyncRequestFactory as DjangoAsyncRequestFactory
+
 from django.utils.encoding import force_bytes
 from django.utils.http import urlencode
 
@@ -136,7 +140,7 @@ else:
         raise ImproperlyConfigured('coreapi must be installed in order to use CoreAPIClient.')
 
 
-class APIRequestFactory(DjangoRequestFactory):
+class APIRequestFactoryMixin:
     renderer_classes_list = api_settings.TEST_REQUEST_RENDERER_CLASSES
     default_format = api_settings.TEST_REQUEST_DEFAULT_FORMAT
 
@@ -240,6 +244,15 @@ class APIRequestFactory(DjangoRequestFactory):
         return request
 
 
+class APIRequestFactory(APIRequestFactoryMixin, DjangoRequestFactory):
+    pass
+
+
+if django.VERSION >= (4, 1):
+    class APIAsyncRequestFactory(APIRequestFactoryMixin, DjangoAsyncRequestFactory):
+        pass
+
+
 class ForceAuthClientHandler(ClientHandler):
     """
     A patched version of ClientHandler that can enforce authentication

rest_framework/throttling.py

@@ -6,6 +6,9 @@ import time
 from django.core.cache import cache as default_cache
 from django.core.exceptions import ImproperlyConfigured
 
+from rest_framework.compat import (
+    async_to_sync, iscoroutinefunction, sync_to_async
+)
 from rest_framework.settings import api_settings
 
 
@@ -64,6 +67,8 @@ class SimpleRateThrottle(BaseThrottle):
     cache_format = 'throttle_%(scope)s_%(ident)s'
     scope = None
     THROTTLE_RATES = api_settings.DEFAULT_THROTTLE_RATES
+    sync_capable = True
+    async_capable = True
 
     def __init__(self):
         if not getattr(self, 'rate', None):
@@ -113,23 +118,52 @@ class SimpleRateThrottle(BaseThrottle):
         On success calls `throttle_success`.
         On failure calls `throttle_failure`.
         """
-        if self.rate is None:
-            return True
+        if getattr(view, 'view_is_async', False):
 
-        self.key = self.get_cache_key(request, view)
-        if self.key is None:
-            return True
+            async def func():
+                if self.rate is None:
+                    return True
 
-        self.history = self.cache.get(self.key, [])
-        self.now = self.timer()
+                self.key = self.get_cache_key(request, view)
+                if self.key is None:
+                    return True
 
-        # Drop any requests from the history which have now passed the
-        # throttle duration
-        while self.history and self.history[-1] <= self.now - self.duration:
-            self.history.pop()
-        if len(self.history) >= self.num_requests:
-            return self.throttle_failure()
-        return self.throttle_success()
+                self.history = self.cache.get(self.key, [])
+                if iscoroutinefunction(self.timer):
+                    self.now = await self.timer()
+                else:
+                    self.now = await sync_to_async(self.timer)()
+
+                # Drop any requests from the history which have now passed the
+                # throttle duration
+                while self.history and self.history[-1] <= self.now - self.duration:
+                    self.history.pop()
+                if len(self.history) >= self.num_requests:
+                    return self.throttle_failure()
+                return self.throttle_success()
+
+            return func()
+        else:
+            if self.rate is None:
+                return True
+
+            self.key = self.get_cache_key(request, view)
+            if self.key is None:
+                return True
+
+            self.history = self.cache.get(self.key, [])
+            if iscoroutinefunction(self.timer):
+                self.now = async_to_sync(self.timer)()
+            else:
+                self.now = self.timer()
+
+            # Drop any requests from the history which have now passed the
+            # throttle duration
+            while self.history and self.history[-1] <= self.now - self.duration:
+                self.history.pop()
+            if len(self.history) >= self.num_requests:
+                return self.throttle_failure()
+            return self.throttle_success()
 
     def throttle_success(self):
         """
@@ -210,6 +244,8 @@ class ScopedRateThrottle(SimpleRateThrottle):
     user id of the request, and the scope of the view being accessed.
     """
     scope_attr = 'throttle_scope'
+    sync_capable = True
+    async_capable = True
 
     def __init__(self):
         # Override the usual SimpleRateThrottle, because we can't determine
@@ -220,17 +256,34 @@ class ScopedRateThrottle(SimpleRateThrottle):
         # We can only determine the scope once we're called by the view.
         self.scope = getattr(view, self.scope_attr, None)
 
-        # If a view does not have a `throttle_scope` always allow the request
-        if not self.scope:
-            return True
+        if getattr(view, 'view_is_async', False):
 
-        # Determine the allowed request rate as we normally would during
-        # the `__init__` call.
-        self.rate = self.get_rate()
-        self.num_requests, self.duration = self.parse_rate(self.rate)
+            async def func(allow_request):
+                # If a view does not have a `throttle_scope` always allow the request
+                if not self.scope:
+                    return True
 
-        # We can now proceed as normal.
-        return super().allow_request(request, view)
+                # Determine the allowed request rate as we normally would during
+                # the `__init__` call.
+                self.rate = self.get_rate()
+                self.num_requests, self.duration = self.parse_rate(self.rate)
+
+                # We can now proceed as normal.
+                return await allow_request(request, view)
+
+            return func(super().allow_request)
+        else:
+            # If a view does not have a `throttle_scope` always allow the request
+            if not self.scope:
+                return True
+
+            # Determine the allowed request rate as we normally would during
+            # the `__init__` call.
+            self.rate = self.get_rate()
+            self.num_requests, self.duration = self.parse_rate(self.rate)
+
+            # We can now proceed as normal.
+            return super().allow_request(request, view)
 
     def get_cache_key(self, request, view):
         """

rest_framework/views.py

@@ -1,6 +1,8 @@
 """
 Provides an APIView class that is the base of all views in REST framework.
 """
+import asyncio
+
 from django.conf import settings
 from django.core.exceptions import PermissionDenied
 from django.db import connections, models
@@ -12,6 +14,9 @@ from django.views.decorators.csrf import csrf_exempt
 from django.views.generic import View
 
 from rest_framework import exceptions, status
+from rest_framework.compat import (
+    async_to_sync, iscoroutinefunction, sync_to_async
+)
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.schemas import DefaultSchema
@@ -328,13 +333,52 @@ class APIView(View):
         Check if the request should be permitted.
         Raises an appropriate exception if the request is not permitted.
         """
+        async_permissions, sync_permissions = [], []
         for permission in self.get_permissions():
-            if not permission.has_permission(request, self):
-                self.permission_denied(
-                    request,
-                    message=getattr(permission, 'message', None),
-                    code=getattr(permission, 'code', None)
-                )
+            if iscoroutinefunction(permission.has_permission):
+                async_permissions.append(permission)
+            else:
+                sync_permissions.append(permission)
+
+        async def check_async():
+            results = await asyncio.gather(
+                *(permission.has_permission(request, self) for permission in
+                  async_permissions), return_exceptions=True
+            )
+
+            for idx in range(len(async_permissions)):
+                if isinstance(results[idx], Exception):
+                    raise results[idx]
+                elif not results[idx]:
+                    self.permission_denied(
+                        request,
+                        message=getattr(async_permissions[idx], "message", None),
+                        code=getattr(async_permissions[idx], "code", None),
+                    )
+
+        def check_sync():
+            for permission in sync_permissions:
+                if not permission.has_permission(request, self):
+                    self.permission_denied(
+                        request,
+                        message=getattr(permission, 'message', None),
+                        code=getattr(permission, 'code', None)
+                    )
+
+        if getattr(self, 'view_is_async', False):
+
+            async def func():
+                if async_permissions:
+                    await check_async()
+                if sync_permissions:
+                    await sync_to_async(check_sync)()
+
+            return func()
+        else:
+            if sync_permissions:
+                check_sync()
+            if async_permissions:
+                async_to_sync(check_async)
 
     def check_object_permissions(self, request, obj):
         """
@@ -354,21 +398,79 @@ class APIView(View):
         Check if request should be throttled.
         Raises an appropriate exception if the request is throttled.
         """
-        throttle_durations = []
+        async_throttle_durations, sync_throttle_durations = [], []
+        view_is_async = getattr(self, 'view_is_async', False)
         for throttle in self.get_throttles():
-            if not throttle.allow_request(request, self):
-                throttle_durations.append(throttle.wait())
+            throttle_can_sync = getattr(throttle, "sync_capable", True)
+            throttle_can_async = getattr(throttle, "async_capable", False)
+            if not throttle_can_sync and not throttle_can_async:
+                raise RuntimeError(
+                    "Throttle %s must have at least one of "
+                    "sync_capable/async_capable set to True." % throttle.__class__.__name__
+                )
+            elif not view_is_async and throttle_can_sync:
+                throttle_is_async = False
+            elif iscoroutinefunction(throttle.allow_request):
+                throttle_is_async = True
+            else:
+                throttle_is_async = throttle_can_async
+            if throttle_is_async:
+                async_throttle_durations.append(throttle)
+            else:
+                sync_throttle_durations.append(throttle)
 
-        if throttle_durations:
-            # Filter out `None` values which may happen in case of config / rate
-            # changes, see #1438
-            durations = [
-                duration for duration in throttle_durations
-                if duration is not None
-            ]
+        async def async_throttles():
+            for throttle in async_throttle_durations:
+                if not await throttle.allow_request(request, self):
+                    yield throttle.wait()
 
-            duration = max(durations, default=None)
-            self.throttled(request, duration)
+        def sync_throttles():
+            for throttle in sync_throttle_durations:
+                if not throttle.allow_request(request, self):
+                    yield throttle.wait()
+
+        if view_is_async:
+
+            async def func():
+                throttle_durations = []
+
+                if async_throttle_durations:
+                    throttle_durations.extend([duration async for duration in async_throttles()])
+
+                if sync_throttle_durations:
+                    throttle_durations.extend(duration for duration in sync_throttles())
+
+                if throttle_durations:
+                    # Filter out `None` values which may happen in case of config / rate
+                    # changes, see #1438
+                    durations = [
+                        duration for duration in throttle_durations
+                        if duration is not None
+                    ]
+
+                    duration = max(durations, default=None)
+                    self.throttled(request, duration)
+
+            return func()
+        else:
+            throttle_durations = []
+
+            if sync_throttle_durations:
+                throttle_durations.extend(sync_throttles())
+
+            if async_throttle_durations:
+                throttle_durations.extend(async_to_sync(async_throttles)())
+
+            if throttle_durations:
+                # Filter out `None` values which may happen in case of config / rate
+                # changes, see #1438
+                durations = [
+                    duration for duration in throttle_durations
+                    if duration is not None
+                ]
+
+                duration = max(durations, default=None)
+                self.throttled(request, duration)
 
     def determine_version(self, request, *args, **kwargs):
         """
@@ -410,10 +512,20 @@ class APIView(View):
         version, scheme = self.determine_version(request, *args, **kwargs)
         request.version, request.versioning_scheme = version, scheme
 
-        # Ensure that the incoming request is permitted
-        self.perform_authentication(request)
-        self.check_permissions(request)
-        self.check_throttles(request)
+        if getattr(self, 'view_is_async', False):
+
+            async def func():
+                # Ensure that the incoming request is permitted
+                await sync_to_async(self.perform_authentication)(request)
+                await self.check_permissions(request)
+                await self.check_throttles(request)
+
+            return func()
+        else:
+            # Ensure that the incoming request is permitted
+            self.perform_authentication(request)
+            self.check_permissions(request)
+            self.check_throttles(request)
 
     def finalize_response(self, request, response, *args, **kwargs):
         """
@@ -469,7 +581,15 @@ class APIView(View):
             self.raise_uncaught_exception(exc)
 
         response.exception = True
-        return response
+
+        if getattr(self, 'view_is_async', False):
+
+            async def func():
+                return response
+
+            return func()
+        else:
+            return response
 
     def raise_uncaught_exception(self, exc):
         if settings.DEBUG:
@@ -493,23 +613,49 @@ class APIView(View):
         self.request = request
         self.headers = self.default_response_headers  # deprecate?
 
-        try:
-            self.initial(request, *args, **kwargs)
+        if getattr(self, 'view_is_async', False):
 
-            # Get the appropriate handler method
-            if request.method.lower() in self.http_method_names:
-                handler = getattr(self, request.method.lower(),
-                                  self.http_method_not_allowed)
-            else:
-                handler = self.http_method_not_allowed
+            async def func():
 
-            response = handler(request, *args, **kwargs)
+                try:
+                    await self.initial(request, *args, **kwargs)
 
-        except Exception as exc:
-            response = self.handle_exception(exc)
+                    # Get the appropriate handler method
+                    if request.method.lower() in self.http_method_names:
+                        handler = getattr(self, request.method.lower(),
+                                          self.http_method_not_allowed)
+                    else:
+                        handler = self.http_method_not_allowed
 
-        self.response = self.finalize_response(request, response, *args, **kwargs)
-        return self.response
+                    response = await handler(request, *args, **kwargs)
+
+                except Exception as exc:
+                    response = await self.handle_exception(exc)
+
+                return self.finalize_response(request, response, *args, **kwargs)
+
+            self.response = func()
+
+            return self.response
+        else:
+            try:
+                self.initial(request, *args, **kwargs)
+
+                # Get the appropriate handler method
+                if request.method.lower() in self.http_method_names:
+                    handler = getattr(self, request.method.lower(),
+                                      self.http_method_not_allowed)
+                else:
+                    handler = self.http_method_not_allowed
+
+                response = handler(request, *args, **kwargs)
+
+            except Exception as exc:
+                response = self.handle_exception(exc)
+
+            self.response = self.finalize_response(request, response, *args, **kwargs)
+
+            return self.response
 
     def options(self, request, *args, **kwargs):
         """
@@ -518,4 +664,12 @@ class APIView(View):
         if self.metadata_class is None:
             return self.http_method_not_allowed(request, *args, **kwargs)
         data = self.metadata_class().determine_metadata(request, self)
-        return Response(data, status=status.HTTP_200_OK)
+
+        if getattr(self, 'view_is_async', False):
+
+            async def func():
+                return Response(data, status=status.HTTP_200_OK)
+
+            return func()
+        else:
+            return Response(data, status=status.HTTP_200_OK)

tests/test_throttling.py

@@ -1,7 +1,7 @@
 """
 Tests for the throttling implementations in the permissions module.
 """
-
+import django
 import pytest
 from django.contrib.auth.models import User
 from django.core.cache import cache
@@ -9,10 +9,15 @@ from django.core.exceptions import ImproperlyConfigured
 from django.http import HttpRequest
 from django.test import TestCase
 
+from rest_framework.compat import async_to_sync
 from rest_framework.request import Request
 from rest_framework.response import Response
 from rest_framework.settings import api_settings
 from rest_framework.test import APIRequestFactory, force_authenticate
+
+if django.VERSION >= (4, 1):
+    from rest_framework.test import APIAsyncRequestFactory
+
 from rest_framework.throttling import (
     AnonRateThrottle, BaseThrottle, ScopedRateThrottle, SimpleRateThrottle,
     UserRateThrottle
@@ -43,6 +48,14 @@ class NonTimeThrottle(BaseThrottle):
         return False
 
 
+class NonTimeAsyncThrottle(BaseThrottle):
+    def allow_request(self, request, view):
+        if not hasattr(self.__class__, 'called'):
+            self.__class__.called = True
+            return True
+        return False
+
+
 class MockView_DoubleThrottling(APIView):
     throttle_classes = (User3SecRateThrottle, User6MinRateThrottle,)
 
@@ -50,6 +63,13 @@ class MockView_DoubleThrottling(APIView):
         return Response('foo')
 
 
+class MockAsyncView_DoubleThrottling(APIView):
+    throttle_classes = (User3SecRateThrottle, User6MinRateThrottle,)
+
+    async def get(self, request):
+        return Response('foo')
+
+
 class MockView(APIView):
     throttle_classes = (User3SecRateThrottle,)
 
@@ -57,6 +77,13 @@ class MockView(APIView):
         return Response('foo')
 
 
+class MockAsyncView(APIView):
+    throttle_classes = (User3SecRateThrottle,)
+
+    async def get(self, request):
+        return Response('foo')
+
+
 class MockView_MinuteThrottling(APIView):
     throttle_classes = (User3MinRateThrottle,)
 
@@ -64,6 +91,13 @@ class MockView_MinuteThrottling(APIView):
         return Response('foo')
 
 
+class MockAsyncView_MinuteThrottling(APIView):
+    throttle_classes = (User3MinRateThrottle,)
+
+    async def get(self, request):
+        return Response('foo')
+
+
 class MockView_NonTimeThrottling(APIView):
     throttle_classes = (NonTimeThrottle,)
 
@@ -71,6 +105,13 @@ class MockView_NonTimeThrottling(APIView):
         return Response('foo')
 
 
+class MockAsyncView_NonTimeThrottling(APIView):
+    throttle_classes = (NonTimeAsyncThrottle,)
+
+    async def get(self, request):
+        return Response('foo')
+
+
 class ThrottlingTests(TestCase):
     def setUp(self):
         """
@@ -252,12 +293,198 @@ class ThrottlingTests(TestCase):
         self.assertFalse('Retry-After' in response)
 
 
+@pytest.mark.skipif(
+    django.VERSION < (4, 1),
+    reason="Async view support requires Django 4.1 or higher",
+)
+class AsyncThrottlingTests(TestCase):
+    def setUp(self):
+        """
+        Reset the cache so that no throttles will be active
+        """
+        cache.clear()
+        self.factory = APIAsyncRequestFactory()
+
+    def test_requests_are_throttled(self):
+        """
+        Ensure request rate is limited
+        """
+        request = self.factory.get('/')
+        for dummy in range(4):
+            response = async_to_sync(MockAsyncView.as_view())(request)
+        assert response.status_code == 429
+
+    def set_throttle_timer(self, view, value):
+        """
+        Explicitly set the timer, overriding time.time()
+        """
+        for cls in view.throttle_classes:
+            cls.timer = lambda self: value
+
+    def test_request_throttling_expires(self):
+        """
+        Ensure request rate is limited for a limited duration only
+        """
+        self.set_throttle_timer(MockAsyncView, 0)
+
+        request = self.factory.get('/')
+        for dummy in range(4):
+            response = async_to_sync(MockAsyncView.as_view())(request)
+        assert response.status_code == 429
+
+        # Advance the timer by one second
+        self.set_throttle_timer(MockAsyncView, 1)
+
+        response = async_to_sync(MockAsyncView.as_view())(request)
+        assert response.status_code == 200
+
+    async def ensure_is_throttled(self, view, expect):
+        request = self.factory.get('/')
+        request.user = await User.objects.acreate(username='a')
+        for dummy in range(3):
+            await view.as_view()(request)
+        request.user = await User.objects.acreate(username='b')
+        response = await view.as_view()(request)
+        assert response.status_code == expect
+
+    def test_request_throttling_is_per_user(self):
+        """
+        Ensure request rate is only limited per user, not globally for
+        PerUserThrottles
+        """
+        async_to_sync(self.ensure_is_throttled)(MockAsyncView, 200)
+
+    def test_request_throttling_multiple_throttles(self):
+        """
+        Ensure all throttle classes see each request even when the request is
+        already being throttled
+        """
+        self.set_throttle_timer(MockAsyncView_DoubleThrottling, 0)
+        request = self.factory.get('/')
+        for dummy in range(4):
+            response = async_to_sync(MockAsyncView_DoubleThrottling.as_view())(request)
+        assert response.status_code == 429
+        assert int(response['retry-after']) == 1
+
+        # At this point our client made 4 requests (one was throttled) in a
+        # second. If we advance the timer by one additional second, the client
+        # should be allowed to make 2 more before being throttled by the 2nd
+        # throttle class, which has a limit of 6 per minute.
+        self.set_throttle_timer(MockAsyncView_DoubleThrottling, 1)
+        for dummy in range(2):
+            response = async_to_sync(MockAsyncView_DoubleThrottling.as_view())(request)
+            assert response.status_code == 200
+
+        response = async_to_sync(MockAsyncView_DoubleThrottling.as_view())(request)
+        assert response.status_code == 429
+        assert int(response['retry-after']) == 59
+
+        # Just to make sure check again after two more seconds.
+        self.set_throttle_timer(MockAsyncView_DoubleThrottling, 2)
+        response = async_to_sync(MockAsyncView_DoubleThrottling.as_view())(request)
+        assert response.status_code == 429
+        assert int(response['retry-after']) == 58
+
+    def test_throttle_rate_change_negative(self):
+        self.set_throttle_timer(MockAsyncView_DoubleThrottling, 0)
+        request = self.factory.get('/')
+        for dummy in range(24):
+            response = async_to_sync(MockAsyncView_DoubleThrottling.as_view())(request)
+        assert response.status_code == 429
+        assert int(response['retry-after']) == 60
+
+        previous_rate = User3SecRateThrottle.rate
+        try:
+            User3SecRateThrottle.rate = '1/sec'
+
+            for dummy in range(24):
+                response = async_to_sync(MockAsyncView_DoubleThrottling.as_view())(request)
+
+            assert response.status_code == 429
+            assert int(response['retry-after']) == 60
+        finally:
+            # reset
+            User3SecRateThrottle.rate = previous_rate
+
+    async def ensure_response_header_contains_proper_throttle_field(self, view, expected_headers):
+        """
+        Ensure the response returns an Retry-After field with status and next attributes
+        set properly.
+        """
+        request = self.factory.get('/')
+        for timer, expect in expected_headers:
+            self.set_throttle_timer(view, timer)
+            response = await view.as_view()(request)
+            if expect is not None:
+                assert response['Retry-After'] == expect
+            else:
+                assert not'Retry-After' in response
+
+    def test_seconds_fields(self):
+        """
+        Ensure for second based throttles.
+        """
+        async_to_sync(self.ensure_response_header_contains_proper_throttle_field)(
+            MockAsyncView, (
+                (0, None),
+                (0, None),
+                (0, None),
+                (0, '1')
+            )
+        )
+
+    def test_minutes_fields(self):
+        """
+        Ensure for minute based throttles.
+        """
+        async_to_sync(self.ensure_response_header_contains_proper_throttle_field)(
+            MockAsyncView_MinuteThrottling, (
+                (0, None),
+                (0, None),
+                (0, None),
+                (0, '60')
+            )
+        )
+
+    def test_next_rate_remains_constant_if_followed(self):
+        """
+        If a client follows the recommended next request rate,
+        the throttling rate should stay constant.
+        """
+        async_to_sync(self.ensure_response_header_contains_proper_throttle_field)(
+            MockAsyncView_MinuteThrottling, (
+                (0, None),
+                (20, None),
+                (40, None),
+                (60, None),
+                (80, None)
+            )
+        )
+
+    def test_non_time_throttle(self):
+        """
+        Ensure for second based throttles.
+        """
+        request = self.factory.get('/')
+
+        self.assertFalse(hasattr(MockAsyncView_NonTimeThrottling.throttle_classes[0], 'called'))
+
+        response = async_to_sync(MockAsyncView_NonTimeThrottling.as_view())(request)
+        self.assertFalse('Retry-After' in response)
+
+        self.assertTrue(MockAsyncView_NonTimeThrottling.throttle_classes[0].called)
+
+        response = async_to_sync(MockAsyncView_NonTimeThrottling.as_view())(request)
+        self.assertFalse('Retry-After' in response)
+
+
 class ScopedRateThrottleTests(TestCase):
     """
     Tests for ScopedRateThrottle.
     """
 
     def setUp(self):
+        cache.clear()
         self.throttle = ScopedRateThrottle()
 
         class XYScopedRateThrottle(ScopedRateThrottle):
@@ -372,6 +599,131 @@ class ScopedRateThrottleTests(TestCase):
         assert cache_key == 'throttle_user_%s' % user.pk
 
 
+@pytest.mark.skipif(
+    django.VERSION < (4, 1),
+    reason="Async view support requires Django 4.1 or higher",
+)
+class AsyncScopedRateThrottleTests(TestCase):
+    """
+    Tests for ScopedRateThrottle.
+    """
+
+    def setUp(self):
+        cache.clear()
+        self.throttle = ScopedRateThrottle()
+
+        class XYScopedRateThrottle(ScopedRateThrottle):
+            TIMER_SECONDS = 0
+            THROTTLE_RATES = {'x': '3/min', 'y': '1/min'}
+
+            async def timer(self):
+                return self.TIMER_SECONDS
+
+        class XView(APIView):
+            throttle_classes = (XYScopedRateThrottle,)
+            throttle_scope = 'x'
+
+            async def get(self, request):
+                return Response('x')
+
+        class YView(APIView):
+            throttle_classes = (XYScopedRateThrottle,)
+            throttle_scope = 'y'
+
+            async def get(self, request):
+                return Response('y')
+
+        class UnscopedView(APIView):
+            throttle_classes = (XYScopedRateThrottle,)
+
+            async def get(self, request):
+                return Response('y')
+
+        self.throttle_class = XYScopedRateThrottle
+        self.factory = APIAsyncRequestFactory()
+        self.x_view = XView.as_view()
+        self.y_view = YView.as_view()
+        self.unscoped_view = UnscopedView.as_view()
+
+    def increment_timer(self, seconds=1):
+        self.throttle_class.TIMER_SECONDS += seconds
+
+    def test_scoped_rate_throttle(self):
+        request = self.factory.get('/')
+
+        # Should be able to hit x view 3 times per minute.
+        response = async_to_sync(self.x_view)(request)
+        assert response.status_code == 200
+
+        self.increment_timer()
+        response = async_to_sync(self.x_view)(request)
+        assert response.status_code == 200
+
+        self.increment_timer()
+        response = async_to_sync(self.x_view)(request)
+        assert response.status_code == 200
+        self.increment_timer()
+        response = async_to_sync(self.x_view)(request)
+        assert response.status_code == 429
+
+        # Should be able to hit y view 1 time per minute.
+        self.increment_timer()
+        response = async_to_sync(self.y_view)(request)
+        assert response.status_code == 200
+
+        self.increment_timer()
+        response = async_to_sync(self.y_view)(request)
+        assert response.status_code == 429
+
+        # Ensure throttles properly reset by advancing the rest of the minute
+        self.increment_timer(55)
+
+        # Should still be able to hit x view 3 times per minute.
+        response = async_to_sync(self.x_view)(request)
+        assert response.status_code == 200
+
+        self.increment_timer()
+        response = async_to_sync(self.x_view)(request)
+        assert response.status_code == 200
+
+        self.increment_timer()
+        response = async_to_sync(self.x_view)(request)
+        assert response.status_code == 200
+
+        self.increment_timer()
+        response = async_to_sync(self.x_view)(request)
+        assert response.status_code == 429
+
+        # Should still be able to hit y view 1 time per minute.
+        self.increment_timer()
+        response = async_to_sync(self.y_view)(request)
+        assert response.status_code == 200
+
+        self.increment_timer()
+        response = async_to_sync(self.y_view)(request)
+        assert response.status_code == 429
+
+    def test_unscoped_view_not_throttled(self):
+        request = self.factory.get('/')
+
+        for idx in range(10):
+            self.increment_timer()
+            response = async_to_sync(self.unscoped_view)(request)
+            assert response.status_code == 200
+
+    def test_get_cache_key_returns_correct_key_if_user_is_authenticated(self):
+        class DummyView:
+            throttle_scope = 'user'
+
+        request = Request(HttpRequest())
+        user = User.objects.create(username='test')
+        force_authenticate(request, user)
+        request.user = user
+        self.throttle.allow_request(request, DummyView())
+        cache_key = self.throttle.get_cache_key(request, view=DummyView())
+        assert cache_key == 'throttle_user_%s' % user.pk
+
+
 class XffTestingBase(TestCase):
     def setUp(self):
 
@@ -400,6 +752,34 @@ class XffTestingBase(TestCase):
         setattr(api_settings, 'NUM_PROXIES', num_proxies)
 
 
+class AsyncXffTestingBase(TestCase):
+    def setUp(self):
+
+        class Throttle(ScopedRateThrottle):
+            THROTTLE_RATES = {'test_limit': '1/day'}
+            TIMER_SECONDS = 0
+
+            async def timer(self):
+                return self.TIMER_SECONDS
+
+        class View(APIView):
+            throttle_classes = (Throttle,)
+            throttle_scope = 'test_limit'
+
+            async def get(self, request):
+                return Response('test_limit')
+
+        cache.clear()
+        self.throttle = Throttle()
+        self.view = View.as_view()
+        self.request = APIAsyncRequestFactory().get('/some_uri')
+        self.request.META['REMOTE_ADDR'] = '3.3.3.3'
+        self.request.META['HTTP_X_FORWARDED_FOR'] = '0.0.0.0, 1.1.1.1, 2.2.2.2'
+
+    def config_proxy(self, num_proxies):
+        setattr(api_settings, 'NUM_PROXIES', num_proxies)
+
+
 class IdWithXffBasicTests(XffTestingBase):
     def test_accepts_request_under_limit(self):
         self.config_proxy(0)
@@ -411,6 +791,21 @@ class IdWithXffBasicTests(XffTestingBase):
         assert self.view(self.request).status_code == 429
 
 
+@pytest.mark.skipif(
+    django.VERSION < (4, 1),
+    reason="Async view support requires Django 4.1 or higher",
+)
+class AsyncIdWithXffBasicTests(AsyncXffTestingBase):
+    def test_accepts_request_under_limit(self):
+        self.config_proxy(0)
+        assert async_to_sync(self.view)(self.request).status_code == 200
+
+    def test_denies_request_over_limit(self):
+        self.config_proxy(0)
+        async_to_sync(self.view)(self.request)
+        assert async_to_sync(self.view)(self.request).status_code == 429
+
+
 class XffSpoofingTests(XffTestingBase):
     def test_xff_spoofing_doesnt_change_machine_id_with_one_app_proxy(self):
         self.config_proxy(1)
@@ -425,6 +820,24 @@ class XffSpoofingTests(XffTestingBase):
         assert self.view(self.request).status_code == 429
 
 
+@pytest.mark.skipif(
+    django.VERSION < (4, 1),
+    reason="Async view support requires Django 4.1 or higher",
+)
+class AsyncXffSpoofingTests(AsyncXffTestingBase):
+    def test_xff_spoofing_doesnt_change_machine_id_with_one_app_proxy(self):
+        self.config_proxy(1)
+        async_to_sync(self.view)(self.request)
+        self.request.META['HTTP_X_FORWARDED_FOR'] = '4.4.4.4, 5.5.5.5, 2.2.2.2'
+        assert async_to_sync(self.view)(self.request).status_code == 429
+
+    def test_xff_spoofing_doesnt_change_machine_id_with_two_app_proxies(self):
+        self.config_proxy(2)
+        async_to_sync(self.view)(self.request)
+        self.request.META['HTTP_X_FORWARDED_FOR'] = '4.4.4.4, 1.1.1.1, 2.2.2.2'
+        assert async_to_sync(self.view)(self.request).status_code == 429
+
+
 class XffUniqueMachinesTest(XffTestingBase):
     def test_unique_clients_are_counted_independently_with_one_proxy(self):
         self.config_proxy(1)
@@ -439,6 +852,24 @@ class XffUniqueMachinesTest(XffTestingBase):
         assert self.view(self.request).status_code == 200
 
 
+@pytest.mark.skipif(
+    django.VERSION < (4, 1),
+    reason="Async view support requires Django 4.1 or higher",
+)
+class AsyncXffUniqueMachinesTest(AsyncXffTestingBase):
+    def test_unique_clients_are_counted_independently_with_one_proxy(self):
+        self.config_proxy(1)
+        async_to_sync(self.view)(self.request)
+        self.request.META['HTTP_X_FORWARDED_FOR'] = '0.0.0.0, 1.1.1.1, 7.7.7.7'
+        assert async_to_sync(self.view)(self.request).status_code == 200
+
+    def test_unique_clients_are_counted_independently_with_two_proxies(self):
+        self.config_proxy(2)
+        async_to_sync(self.view)(self.request)
+        self.request.META['HTTP_X_FORWARDED_FOR'] = '0.0.0.0, 7.7.7.7, 2.2.2.2'
+        assert async_to_sync(self.view)(self.request).status_code == 200
+
+
 class BaseThrottleTests(TestCase):
 
     def test_allow_request_raises_not_implemented_error(self):

tests/test_views.py

@@ -1,8 +1,12 @@
 import copy
 
+import django
+import pytest
+from django.contrib.auth.models import User
 from django.test import TestCase
 
 from rest_framework import status
+from rest_framework.compat import async_to_sync
 from rest_framework.decorators import api_view
 from rest_framework.response import Response
 from rest_framework.settings import APISettings, api_settings
@@ -22,16 +26,36 @@ class BasicView(APIView):
         return Response({'method': 'POST', 'data': request.data})
 
 
+class BasicAsyncView(APIView):
+    async def get(self, request, *args, **kwargs):
+        return Response({'method': 'GET'})
+
+    async def post(self, request, *args, **kwargs):
+        return Response({'method': 'POST', 'data': request.data})
+
+
 @api_view(['GET', 'POST', 'PUT', 'PATCH'])
 def basic_view(request):
     if request.method == 'GET':
-        return {'method': 'GET'}
+        return Response({'method': 'GET'})
     elif request.method == 'POST':
-        return {'method': 'POST', 'data': request.data}
+        return Response({'method': 'POST', 'data': request.data})
     elif request.method == 'PUT':
-        return {'method': 'PUT', 'data': request.data}
+        return Response({'method': 'PUT', 'data': request.data})
     elif request.method == 'PATCH':
-        return {'method': 'PATCH', 'data': request.data}
+        return Response({'method': 'PATCH', 'data': request.data})
+
+
+@api_view(['GET', 'POST', 'PUT', 'PATCH'])
+async def basic_async_view(request):
+    if request.method == 'GET':
+        return Response({'method': 'GET'})
+    elif request.method == 'POST':
+        return Response({'method': 'POST', 'data': request.data})
+    elif request.method == 'PUT':
+        return Response({'method': 'PUT', 'data': request.data})
+    elif request.method == 'PATCH':
+        return Response({'method': 'PATCH', 'data': request.data})
 
 
 class ErrorView(APIView):
@@ -72,6 +96,36 @@ class ClassBasedViewIntegrationTests(TestCase):
     def setUp(self):
         self.view = BasicView.as_view()
 
+    def test_get_succeeds(self):
+        request = factory.get('/')
+        response = self.view(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == {'method': 'GET'}
+
+    def test_logged_in_get_succeeds(self):
+        user = User.objects.create_user('user', 'user@example.com', 'password')
+        request = factory.get('/')
+        del user.is_active
+        request.user = user
+        response = self.view(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == {'method': 'GET'}
+
+    def test_post_succeeds(self):
+        request = factory.post('/', {'test': 'foo'})
+        response = self.view(request)
+        expected = {
+            'method': 'POST',
+            'data': {'test': ['foo']}
+        }
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == expected
+
+    def test_options_succeeds(self):
+        request = factory.options('/')
+        response = self.view(request)
+        assert response.status_code == status.HTTP_200_OK
+
     def test_400_parse_error(self):
         request = factory.post('/', 'f00bar', content_type='application/json')
         response = self.view(request)
@@ -82,10 +136,88 @@ class ClassBasedViewIntegrationTests(TestCase):
         assert sanitise_json_error(response.data) == expected
 
 
+@pytest.mark.skipif(
+    django.VERSION < (4, 1),
+    reason="Async view support requires Django 4.1 or higher",
+)
+class ClassBasedAsyncViewIntegrationTests(TestCase):
+    def setUp(self):
+        self.view = BasicAsyncView.as_view()
+
+    def test_get_succeeds(self):
+        request = factory.get('/')
+        response = async_to_sync(self.view)(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == {'method': 'GET'}
+
+    def test_logged_in_get_succeeds(self):
+        user = User.objects.create_user('user', 'user@example.com', 'password')
+        request = factory.get('/')
+        del user.is_active
+        request.user = user
+        response = async_to_sync(self.view)(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == {'method': 'GET'}
+
+    def test_post_succeeds(self):
+        request = factory.post('/', {'test': 'foo'})
+        response = async_to_sync(self.view)(request)
+        expected = {
+            'method': 'POST',
+            'data': {'test': ['foo']}
+        }
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == expected
+
+    def test_options_succeeds(self):
+        request = factory.options('/')
+        response = async_to_sync(self.view)(request)
+        assert response.status_code == status.HTTP_200_OK
+
+    def test_400_parse_error(self):
+        request = factory.post('/', 'f00bar', content_type='application/json')
+        response = async_to_sync(self.view)(request)
+        expected = {
+            'detail': JSON_ERROR
+        }
+        assert response.status_code == status.HTTP_400_BAD_REQUEST
+        assert sanitise_json_error(response.data) == expected
+
+
 class FunctionBasedViewIntegrationTests(TestCase):
     def setUp(self):
         self.view = basic_view
 
+    def test_get_succeeds(self):
+        request = factory.get('/')
+        response = self.view(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == {'method': 'GET'}
+
+    def test_logged_in_get_succeeds(self):
+        user = User.objects.create_user('user', 'user@example.com', 'password')
+        request = factory.get('/')
+        del user.is_active
+        request.user = user
+        response = self.view(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == {'method': 'GET'}
+
+    def test_post_succeeds(self):
+        request = factory.post('/', {'test': 'foo'})
+        response = self.view(request)
+        expected = {
+            'method': 'POST',
+            'data': {'test': ['foo']}
+        }
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == expected
+
+    def test_options_succeeds(self):
+        request = factory.options('/')
+        response = self.view(request)
+        assert response.status_code == status.HTTP_200_OK
+
     def test_400_parse_error(self):
         request = factory.post('/', 'f00bar', content_type='application/json')
         response = self.view(request)
@@ -96,6 +228,54 @@ class FunctionBasedViewIntegrationTests(TestCase):
         assert sanitise_json_error(response.data) == expected
 
 
+@pytest.mark.skipif(
+    django.VERSION < (4, 1),
+    reason="Async view support requires Django 4.1 or higher",
+)
+class FunctionBasedAsyncViewIntegrationTests(TestCase):
+    def setUp(self):
+        self.view = basic_async_view
+
+    def test_get_succeeds(self):
+        request = factory.get('/')
+        response = async_to_sync(self.view)(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == {'method': 'GET'}
+
+    def test_logged_in_get_succeeds(self):
+        user = User.objects.create_user('user', 'user@example.com', 'password')
+        request = factory.get('/')
+        del user.is_active
+        request.user = user
+        response = async_to_sync(self.view)(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == {'method': 'GET'}
+
+    def test_post_succeeds(self):
+        request = factory.post('/', {'test': 'foo'})
+        response = async_to_sync(self.view)(request)
+        expected = {
+            'method': 'POST',
+            'data': {'test': ['foo']}
+        }
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data == expected
+
+    def test_options_succeeds(self):
+        request = factory.options('/')
+        response = async_to_sync(self.view)(request)
+        assert response.status_code == status.HTTP_200_OK
+
+    def test_400_parse_error(self):
+        request = factory.post('/', 'f00bar', content_type='application/json')
+        response = async_to_sync(self.view)(request)
+        expected = {
+            'detail': JSON_ERROR
+        }
+        assert response.status_code == status.HTTP_400_BAD_REQUEST
+        assert sanitise_json_error(response.data) == expected
+
+
 class TestCustomExceptionHandler(TestCase):
     def setUp(self):
         self.DEFAULT_HANDLER = api_settings.EXCEPTION_HANDLER