Support async view methods in extend_schema_view.

Author: tbeadle

drf_spectacular/drainage.py

@@ -182,8 +182,12 @@ def get_view_method_names(view, schema=None) -> List[str]:
     return [
         item for item in dir(view) if callable(getattr(view, item)) and (
             item in view.http_method_names
-            or item in schema.method_mapping.values()
-            or item == 'list'
+            or (
+                item in schema.async_method_mapping.values()
+                if view.view_is_async
+                else item in schema.method_mapping.values()
+            )
+            or item == ('alist' if view.view_is_async else 'list')
             or hasattr(getattr(view, item), 'mapping')
         )
     ]

drf_spectacular/openapi.py

@@ -57,6 +57,13 @@ class AutoSchema(ViewInspector):
         'patch': 'partial_update',
         'delete': 'destroy',
     }
+    async_method_mapping = {
+        'get': 'aretrieve',
+        'post': 'acreate',
+        'put': 'aupdate',
+        'patch': 'partial_aupdate',
+        'delete': 'adestroy',
+    }
 
     def get_operation(
             self,