fix nested serializer detection & smarter metadata extraction #319

drf_spectacular/openapi.py

@@ -437,8 +437,11 @@ def _map_model_field(self, model_field, direction):
             )
             return build_basic_type(OpenApiTypes.STR)
 
-    def _map_serializer_field(self, field, direction):
-        meta = self._get_serializer_field_meta(field)
+    def _map_serializer_field(self, field, direction, collect_meta=True):
+        if collect_meta:
+            meta = self._get_serializer_field_meta(field)
+        else:
+            meta = {}
 
         if has_override(field, 'field'):
             override = get_override(field, 'field')
@@ -449,7 +452,7 @@ def _map_serializer_field(self, field, direction):
             elif isinstance(override, dict):
                 schema = override
             else:
-                schema = self._map_serializer_field(force_instance(override), direction)
+                schema = self._map_serializer_field(force_instance(override), direction, False)
 
             field_component_name = get_override(field, 'field_component_name')
             if field_component_name:
@@ -469,23 +472,23 @@ def _map_serializer_field(self, field, direction):
             schema = serializer_field_extension.map_serializer_field(self, direction)
             return append_meta(schema, meta)
 
-        # nested serializer
-        if isinstance(field, serializers.Serializer):
-            component = self.resolve_serializer(field, direction)
-            return append_meta(component.ref, meta) if component else None
-
         # nested serializer with many=True gets automatically replaced with ListSerializer
-        if isinstance(field, serializers.ListSerializer):
+        if is_list_serializer(field):
             if is_serializer(field.child):
                 component = self.resolve_serializer(field.child, direction)
                 return append_meta(build_array_type(component.ref), meta) if component else None
             else:
-                schema = self._map_serializer_field(field.child, direction)
+                schema = self._map_serializer_field(field.child, direction, collect_meta)
                 return append_meta(build_array_type(schema), meta)
 
+        # nested serializer
+        if is_serializer(field):
+            component = self.resolve_serializer(field, direction)
+            return append_meta(component.ref, meta) if component else None
+
         # Related fields.
         if isinstance(field, serializers.ManyRelatedField):
-            schema = self._map_serializer_field(field.child_relation, direction)
+            schema = self._map_serializer_field(field.child_relation, direction, collect_meta)
             # remove hand-over initkwargs applying only to outer scope
             schema.pop('description', None)
             schema.pop('readOnly', None)
@@ -542,7 +545,7 @@ def _map_serializer_field(self, field, direction):
                 component = self.resolve_serializer(field.child, direction)
                 return append_meta(build_array_type(component.ref), meta) if component else None
             else:
-                schema = self._map_serializer_field(field.child, direction)
+                schema = self._map_serializer_field(field.child, direction, collect_meta)
                 return append_meta(build_array_type(schema), meta)
 
         # DateField and DateTimeField type is string
@@ -625,7 +628,9 @@ def _map_serializer_field(self, field, direction):
         if anyisinstance(field, [serializers.DictField, serializers.HStoreField]):
             content = build_basic_type(OpenApiTypes.OBJECT)
             if not isinstance(field.child, _UnvalidatedField):
-                content['additionalProperties'] = self._map_serializer_field(field.child, direction)
+                content['additionalProperties'] = self._map_serializer_field(
+                    field.child, direction, collect_meta
+                )
             return append_meta(content, meta)
 
         if isinstance(field, serializers.CharField):

tests/test_polymorphic.py

@@ -3,10 +3,13 @@
 import pytest
 from django.db import models
 from rest_framework import serializers, viewsets
+from rest_framework.decorators import api_view
 from rest_framework.response import Response
 
 from drf_spectacular.openapi import AutoSchema
-from drf_spectacular.utils import OpenApiParameter, PolymorphicProxySerializer, extend_schema
+from drf_spectacular.utils import (
+    OpenApiParameter, PolymorphicProxySerializer, extend_schema, extend_schema_field,
+)
 from tests import assert_schema, generate_schema
 
 
@@ -90,3 +93,27 @@ def test_polymorphic(no_warnings, viewset):
         generate_schema('persons', viewset),
         'tests/test_polymorphic.yml'
     )
+
+
+def test_polymorphic_serializer_as_field_via_extend_schema_field(no_warnings):
+    @extend_schema_field(
+        PolymorphicProxySerializer(
+            component_name='MetaPerson',
+            serializers=[LegalPersonSerializer, NaturalPersonSerializer],
+            resource_type_field_name='type',
+        )
+    )
+    class XField(serializers.DictField):
+        pass
+
+    class XSerializer(serializers.Serializer):
+        field = XField()
+
+    @extend_schema(request=XSerializer, responses=XSerializer)
+    @api_view(['GET'])
+    def view_func(request, format=None):
+        pass  # pragma: no cover
+
+    schema = generate_schema('x', view_function=view_func)
+    assert 'MetaPerson' in schema['components']['schemas']
+    assert 'MetaPerson' in schema['components']['schemas']['X']['properties']['field']['$ref']