Add method mapping to ViewSet actions

Author: Ryan P Kilby

rest_framework/decorators.py

@@ -146,7 +146,8 @@ def action(methods=None, detail=None, name=None, url_path=None, url_name=None, *
     )
 
     def decorator(func):
-        func.bind_to_methods = methods
+        func.mapping = MethodMapper(func, methods)
+
         func.detail = detail
         func.name = name if name else pretty_name(func.__name__)
         func.url_path = url_path if url_path else func.__name__
@@ -156,10 +157,70 @@ def decorator(func):
             'name': func.name,
             'description': func.__doc__ or None
         })
+
         return func
     return decorator
 
 
+class MethodMapper(dict):
+    """
+    Enables mapping HTTP methods to different ViewSet methods for a single,
+    logical action.
+
+    Example usage:
+
+        class MyViewSet(ViewSet):
+
+            @action(detail=False)
+            def example(self, request, **kwargs):
+                ...
+
+            @example.mapping.post
+            def create_example(self, request, **kwargs):
+                ...
+    """
+
+    def __init__(self, action, methods):
+        self.action = action
+        for method in methods:
+            self[method] = self.action.__name__
+
+    def _map(self, method, func):
+        assert method not in self, (
+            "Method '%s' has already been mapped to '.%s'." % (method, self[method]))
+        assert func.__name__ != self.action.__name__, (
+            "Method mapping does not behave like the property decorator. You "
+            "cannot use the same method name for each mapping declaration.")
+
+        self[method] = func.__name__
+
+        return func
+
+    def get(self, func):
+        return self._map('get', func)
+
+    def post(self, func):
+        return self._map('post', func)
+
+    def put(self, func):
+        return self._map('put', func)
+
+    def patch(self, func):
+        return self._map('patch', func)
+
+    def delete(self, func):
+        return self._map('delete', func)
+
+    def head(self, func):
+        return self._map('head', func)
+
+    def options(self, func):
+        return self._map('options', func)
+
+    def trace(self, func):
+        return self._map('trace', func)
+
+
 def detail_route(methods=None, **kwargs):
     """
     Used to mark a method on a ViewSet that should be routed for detail requests.

rest_framework/routers.py

@@ -208,8 +208,7 @@ def _get_dynamic_route(self, route, action):
 
         return Route(
             url=route.url.replace('{url_path}', url_path),
-            mapping={http_method: action.__name__
-                     for http_method in action.bind_to_methods},
+            mapping=action.mapping,
             name=route.name.replace('{url_name}', action.url_name),
             detail=route.detail,
             initkwargs=initkwargs,

rest_framework/viewsets.py

@@ -31,7 +31,7 @@
 
 
 def _is_extra_action(attr):
-    return hasattr(attr, 'bind_to_methods')
+    return hasattr(attr, 'mapping')
 
 
 class ViewSetMixin(object):

tests/test_decorators.py

@@ -177,7 +177,7 @@ def test_defaults(self):
         def test_action(request):
             """Description"""
 
-        assert test_action.bind_to_methods == ['get']
+        assert test_action.mapping == {'get': 'test_action'}
         assert test_action.detail is True
         assert test_action.name == 'Test action'
         assert test_action.url_path == 'test_action'
@@ -195,6 +195,42 @@ def test_action(request):
 
         assert str(excinfo.value) == "@action() missing required argument: 'detail'"
 
+    def test_method_mapping(self):
+        @action(detail=False)
+        def test_action(request):
+            pass
+
+        @test_action.mapping.post
+        def test_action_post(request):
+            pass
+
+        # The secondary handler methods should not have the action attributes
+        for name in ['mapping', 'detail', 'name', 'url_path', 'url_name', 'kwargs']:
+            assert hasattr(test_action, name) and not hasattr(test_action_post, name)
+
+    def test_method_mapping_already_mapped(self):
+        @action(detail=True)
+        def test_action(request):
+            pass
+
+        msg = "Method 'get' has already been mapped to '.test_action'."
+        with self.assertRaisesMessage(AssertionError, msg):
+            @test_action.mapping.get
+            def test_action_get(request):
+                pass
+
+    def test_method_mapping_overwrite(self):
+        @action(detail=True)
+        def test_action():
+            pass
+
+        msg = ("Method mapping does not behave like the property decorator. You "
+               "cannot use the same method name for each mapping declaration.")
+        with self.assertRaisesMessage(AssertionError, msg):
+            @test_action.mapping.post
+            def test_action():
+                pass
+
     def test_detail_route_deprecation(self):
         with pytest.warns(PendingDeprecationWarning) as record:
             @detail_route()

tests/test_routers.py

@@ -7,7 +7,7 @@
 from django.core.exceptions import ImproperlyConfigured
 from django.db import models
 from django.test import TestCase, override_settings
-from django.urls import resolve
+from django.urls import resolve, reverse
 
 from rest_framework import permissions, serializers, viewsets
 from rest_framework.compat import get_regex_pattern
@@ -107,8 +107,23 @@ def action1(self, request, *args, **kwargs):
     def action2(self, request, *args, **kwargs):
         return Response({'method': 'action2'})
 
+    @action(methods=['post'], detail=True)
+    def action3(self, request, pk, *args, **kwargs):
+        return Response({'post': pk})
+
+    @action3.mapping.delete
+    def action3_delete(self, request, pk, *args, **kwargs):
+        return Response({'delete': pk})
+
+
+class TestSimpleRouter(URLPatternsTestCase, TestCase):
+    router = SimpleRouter()
+    router.register('basics', BasicViewSet, base_name='basic')
+
+    urlpatterns = [
+        url(r'^api/', include(router.urls)),
+    ]
 
-class TestSimpleRouter(TestCase):
     def setUp(self):
         self.router = SimpleRouter()
 
@@ -127,6 +142,21 @@ def test_action_routes(self):
             'delete': 'action2',
         }
 
+        assert routes[2].url == '^{prefix}/{lookup}/action3{trailing_slash}$'
+        assert routes[2].mapping == {
+            'post': 'action3',
+            'delete': 'action3_delete',
+        }
+
+    def test_multiple_action_handlers(self):
+        # Standard action
+        response = self.client.post(reverse('basic-action3', args=[1]))
+        assert response.data == {'post': '1'}
+
+        # Additional handler registered with MethodMapper
+        response = self.client.delete(reverse('basic-action3', args=[1]))
+        assert response.data == {'delete': '1'}
+
 
 class TestRootView(URLPatternsTestCase, TestCase):
     urlpatterns = [

tests/test_schemas.py

@@ -97,6 +97,12 @@ def custom_list_action(self, request):
 
     @action(methods=['post', 'get'], detail=False, serializer_class=EmptySerializer)
     def custom_list_action_multiple_methods(self, request):
+        """Custom description."""
+        return super(ExampleViewSet, self).list(self, request)
+
+    @custom_list_action_multiple_methods.mapping.delete
+    def custom_list_action_multiple_methods_delete(self, request):
+        """Deletion description."""
         return super(ExampleViewSet, self).list(self, request)
 
     def get_serializer(self, *args, **kwargs):
@@ -147,7 +153,8 @@ def test_anonymous_request(self):
                     'custom_list_action_multiple_methods': {
                         'read': coreapi.Link(
                             url='/example/custom_list_action_multiple_methods/',
-                            action='get'
+                            action='get',
+                            description='Custom description.',
                         )
                     },
                     'read': coreapi.Link(
@@ -238,12 +245,19 @@ def test_authenticated_request(self):
                     'custom_list_action_multiple_methods': {
                         'read': coreapi.Link(
                             url='/example/custom_list_action_multiple_methods/',
-                            action='get'
+                            action='get',
+                            description='Custom description.',
                         ),
                         'create': coreapi.Link(
                             url='/example/custom_list_action_multiple_methods/',
-                            action='post'
-                        )
+                            action='post',
+                            description='Custom description.',
+                        ),
+                        'delete': coreapi.Link(
+                            url='/example/custom_list_action_multiple_methods/',
+                            action='delete',
+                            description='Deletion description.',
+                        ),
                     },
                     'update': coreapi.Link(
                         url='/example/{id}/',
@@ -526,7 +540,8 @@ def test_schema_for_regular_views(self):
                     'custom_list_action_multiple_methods': {
                         'read': coreapi.Link(
                             url='/example1/custom_list_action_multiple_methods/',
-                            action='get'
+                            action='get',
+                            description='Custom description.',
                         )
                     },
                     'read': coreapi.Link(