Async implementation

rest_framework/compat.py

@@ -41,6 +41,13 @@ def distinct(queryset, base):
     uritemplate = None
 
 
+# async_to_sync is required for async view support
+if django.VERSION >= (4, 1):
+    from asgiref.sync import async_to_sync
+else:
+    async_to_sync = None
+
+
 # coreschema is optional
 try:
     import coreschema

rest_framework/views.py

@@ -482,7 +482,7 @@ def raise_uncaught_exception(self, exc):
     # Note: Views are made CSRF exempt from within `as_view` as to prevent
     # accidental removal of this exemption in cases where `dispatch` needs to
     # be overridden.
-    def dispatch(self, request, *args, **kwargs):
+    def sync_dispatch(self, request, *args, **kwargs):
         """
         `.dispatch()` is pretty much the same as Django's regular dispatch,
         but with extra hooks for startup, finalize, and exception handling.
@@ -511,6 +511,41 @@ def dispatch(self, request, *args, **kwargs):
         self.response = self.finalize_response(request, response, *args, **kwargs)
         return self.response
 
+    async def async_dispatch(self, request, *args, **kwargs):
+        """
+        `.dispatch()` is pretty much the same as Django's regular dispatch,
+        but with extra hooks for startup, finalize, and exception handling.
+        """
+        self.args = args
+        self.kwargs = kwargs
+        request = self.initialize_request(request, *args, **kwargs)
+        self.request = request
+        self.headers = self.default_response_headers  # deprecate?
+
+        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 = await 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 dispatch(self, request, *args, **kwargs):
+        if hasattr(self, 'view_is_async') and self.view_is_async:
+            return self.async_dispatch(request, *args, **kwargs)
+        else:
+            return self.sync_dispatch(request, *args, **kwargs)
+
     def options(self, request, *args, **kwargs):
         """
         Handler method for HTTP 'OPTIONS' request.

tests/test_views.py

@@ -1,8 +1,11 @@
 import copy
 
+import django
+import pytest
 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 +25,24 @@ def post(self, request, *args, **kwargs):
         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})
 
 
 class ErrorView(APIView):
@@ -72,6 +83,22 @@ 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_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_400_parse_error(self):
         request = factory.post('/', 'f00bar', content_type='application/json')
         response = self.view(request)
@@ -86,6 +113,22 @@ 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_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_400_parse_error(self):
         request = factory.post('/', 'f00bar', content_type='application/json')
         response = self.view(request)
@@ -96,6 +139,40 @@ def test_400_parse_error(self):
         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_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_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