From 2227beb0e6cb21d419e1941c835e5320c1ff3ff4 Mon Sep 17 00:00:00 2001
From: "T. Franzel" <tfranzel@users.noreply.github.com>
Date: Thu, 20 May 2021 19:39:11 +0200
Subject: [PATCH] invert component exclusion logic (OpenApiSerializerExtension)
 #351 #391

---
 drf_spectacular/openapi.py | 17 ++++++++---------
 tests/test_regressions.py  | 30 ++++++++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/drf_spectacular/openapi.py b/drf_spectacular/openapi.py
index 3052c52a..9fc4b7f2 100644
--- a/drf_spectacular/openapi.py
+++ b/drf_spectacular/openapi.py
@@ -1179,16 +1179,15 @@ def resolve_serializer(self, serializer, direction) -> ResolvedComponent:
 
             self.registry.register(component)
             component.schema = self._map_serializer(serializer, direction)
-            # 4 cases:
-            #   1. polymorphic container component -> use
-            #   2. concrete component with properties -> use
-            #   3. concrete component without properties -> prob. transactional so discard
-            #   4. explicit list component -> demultiplexed at usage location so discard
-            keep_component = (
-                any(nest_tag in component.schema for nest_tag in ['oneOf', 'allOf', 'anyOf'])
-                or component.schema.get('properties', {})
+
+            discard_component = (
+                # components with empty schemas serve no purpose
+                not component.schema
+                # concrete component without properties are likely only transactional so discard
+                or (component.schema.get('type') == 'object' and not component.schema.get('properties'))
             )
-            if not keep_component:
+
+            if discard_component:
                 del self.registry[component]
                 return ResolvedComponent(None, None)  # sentinel
             return component
diff --git a/tests/test_regressions.py b/tests/test_regressions.py
index b3540039..e6ce6d7c 100644
--- a/tests/test_regressions.py
+++ b/tests/test_regressions.py
@@ -864,7 +864,7 @@ class CustomAuth(TokenAuthentication):
         pass
 
     class XSerializer(serializers.Serializer):
-        field = serializers.IntegerField
+        field = serializers.IntegerField()
 
     class XAPIView(APIView):
         authentication_classes = [CustomAuth]
@@ -1238,7 +1238,7 @@ def view_func(request, format=None):
 
 def test_basic_viewset_without_queryset_with_explicit_pk_typing(no_warnings):
     class XSerializer(serializers.Serializer):
-        field = fields.IntegerField()
+        field = serializers.IntegerField()
 
     class XViewset(viewsets.ViewSet):
         serializer_class = XSerializer
@@ -1845,3 +1845,29 @@ def test_yaml_encoder_parity(no_warnings, value):
     # rest_framework.encoders.JSONEncoder
     assert OpenApiJsonRenderer().render(value)
     assert OpenApiYamlRenderer().render(value)
+
+
+@pytest.mark.parametrize('comp_schema', [
+    {'type': 'number'},
+    {'type': 'array', 'items': {'type': 'number'}},
+])
+def test_serializer_extension_with_non_object_schema(no_warnings, comp_schema):
+    class XSerializer(serializers.Serializer):
+        field = serializers.CharField()
+
+    class XExtension(OpenApiSerializerExtension):
+        target_class = XSerializer
+
+        def map_serializer(self, auto_schema, direction):
+            return comp_schema
+
+    class XAPIView(APIView):
+        @extend_schema(request=XSerializer, responses=XSerializer)
+        def post(self, request):
+            pass  # pragma: no cover
+
+    schema = generate_schema('x', view=XAPIView)
+
+    operation = schema['paths']['/x']['post']
+    assert get_request_schema(operation)['$ref'] == '#/components/schemas/X'
+    assert schema['components']['schemas']['X'] == comp_schema