fix custom http_method_names for actions #1184

drf_spectacular/generators.py

@@ -79,7 +79,11 @@ def _get_api_endpoints(self, patterns, prefix):
     def get_allowed_methods(self, callback):
         if hasattr(callback, 'actions'):
             actions = set(callback.actions)
-            http_method_names = set(callback.cls.http_method_names)
+            if 'http_method_names' in callback.initkwargs:
+                http_method_names = set(callback.initkwargs['http_method_names'])
+            else:
+                http_method_names = set(callback.cls.http_method_names)
+
             methods = [method.upper() for method in actions & http_method_names]
         else:
             # pass to constructor allowed method names to get valid ones

tests/test_regressions.py

@@ -3328,3 +3328,23 @@ def view_func(request, format=None):
 
         assert get_response_schema(schema['paths']['/x']['post']) == ref_schema
         assert get_request_schema(schema['paths']['/x']['post']) == ref_schema
+
+
+def test_customized_http_method_names(no_warnings):
+    class XViewSet(viewsets.ModelViewSet):
+        http_method_names = ['get', 'options', 'head']
+
+        serializer_class = SimpleSerializer
+        queryset = SimpleModel.objects.none()
+
+        @action(
+            detail=True,
+            methods=['post'],
+            http_method_names=['post'],
+        )
+        def favorite(self, request, pk=None):
+            pass  # pragma: no cover
+
+    schema = generate_schema('m', XViewSet)
+
+    assert list(schema['paths'].keys()) == ['/m/', '/m/{id}/', '/m/{id}/favorite/']