Merge branch 'pr5' with improvements. closes #5

drf_spectacular/openapi.py

@@ -17,7 +17,7 @@
 from rest_framework.schemas.utils import get_pk_description, is_list_view
 
 from drf_spectacular.app_settings import spectacular_settings
-from drf_spectacular.plumbing import resolve_basic_type, warn, anyisinstance, force_serializer_instance, is_serializer, follow_field_source
+from drf_spectacular.plumbing import resolve_basic_type, warn, anyisinstance, force_instance, is_serializer, follow_field_source, is_field
 from drf_spectacular.types import OpenApiTypes, PYTHON_TYPE_MAPPING, OPENAPI_TYPE_MAPPING
 from drf_spectacular.utils import PolymorphicProxySerializer
 
@@ -545,7 +545,7 @@ def _map_polymorphic_proxy_serializer(self, method, serializer, nested):
 
         for sub_serializer in serializer.serializers:
             assert is_serializer(sub_serializer), 'sub-serializer must be either a Serializer or a PolymorphicProxySerializer.'
-            sub_serializer = force_serializer_instance(sub_serializer)
+            sub_serializer = force_instance(sub_serializer)
 
             if serializer.resource_type_field_name not in sub_serializer.fields:
                 warn(
@@ -638,8 +638,8 @@ def _map_field_validators(self, field, schema):
     def _map_type_hint(self, method):
         hint = getattr(method, '_spectacular_annotation', None) or typing.get_type_hints(method).get('return')
 
-        if is_serializer(hint):
-            return self._map_serializer_field(method, force_serializer_instance(hint))
+        if is_serializer(hint) or is_field(hint):
+            return self._map_serializer_field(method, force_instance(hint))
         elif hint in PYTHON_TYPE_MAPPING or hint in OPENAPI_TYPE_MAPPING:
             return resolve_basic_type(hint)
         else:
@@ -685,7 +685,7 @@ def _get_request_body(self, path, method):
         if method not in ('PUT', 'PATCH', 'POST'):
             return {}
 
-        serializer = force_serializer_instance(self.get_request_serializer(path, method))
+        serializer = force_instance(self.get_request_serializer(path, method))
 
         if is_serializer(serializer):
             schema = self.resolve_serializer(method, serializer)
@@ -733,7 +733,7 @@ def _get_response_bodies(self, path, method):
 
     def _get_response_for_code(self, path, method, serializer):
         # convenience feature: auto instantiate serializer classes
-        serializer = force_serializer_instance(serializer)
+        serializer = force_instance(serializer)
 
         if not serializer:
             return {'description': 'No response body'}

drf_spectacular/plumbing.py

@@ -2,7 +2,7 @@
 import sys
 
 from django import __version__ as DJANGO_VERSION
-from rest_framework import serializers
+from rest_framework import fields, serializers
 
 from drf_spectacular.types import OPENAPI_TYPE_MAPPING, PYTHON_TYPE_MAPPING, OpenApiTypes
 from drf_spectacular.utils import PolymorphicProxySerializer
@@ -16,20 +16,28 @@ def anyisinstance(obj, type_list):
     return any([isinstance(obj, t) for t in type_list])
 
 
-def force_serializer_instance(serializer):
-    if inspect.isclass(serializer) and issubclass(serializer, serializers.BaseSerializer):
-        return serializer()
+def force_instance(serializer_or_field):
+    if not inspect.isclass(serializer_or_field):
+        return serializer_or_field
+    elif issubclass(serializer_or_field, (serializers.BaseSerializer, fields.Field)):
+        return serializer_or_field()
     else:
-        return serializer
+        return serializer_or_field
 
 
 def is_serializer(obj):
     return anyisinstance(
-        force_serializer_instance(obj),
+        force_instance(obj),
         [serializers.BaseSerializer, PolymorphicProxySerializer]
     )
 
 
+def is_field(obj):
+    # make sure obj is a serializer field and nothing else.
+    # guard against serializers because BaseSerializer(Field)
+    return isinstance(force_instance(obj), fields.Field) and not is_serializer(obj)
+
+
 def resolve_basic_type(type_):
     """
     resolve either enum or actual type and yield schema template for modification

tests/test_extend_schema.py

@@ -39,6 +39,7 @@ class ErrorSerializer(serializers.Serializer):
     field_i = serializers.SerializerMethodField()
     field_j = serializers.SerializerMethodField()
     field_k = serializers.SerializerMethodField()
+    field_l = serializers.SerializerMethodField()
 
     @extend_schema_field(OpenApiTypes.DATETIME)
     def get_field_i(self, object):
@@ -52,6 +53,10 @@ def get_field_j(self, object):
     def get_field_k(self, object):
         return InlineSerializer([], many=True).data
 
+    @extend_schema_field(serializers.ChoiceField(choices=['a', 'b']))
+    def get_field_l(self, object):
+        return object.some_choice
+
 
 with mock.patch('rest_framework.settings.api_settings.DEFAULT_SCHEMA_CLASS', AutoSchema):
     class DoesItAllViewset(viewsets.GenericViewSet):
@@ -71,7 +76,7 @@ class DoesItAllViewset(viewsets.GenericViewSet):
             ],
             description='this weird endpoint needs some explaining',
             deprecated=True,
-            tags=['custom_tag']
+            tags=['custom_tag'],
         )
         def create(self, request, *args, **kwargs):
             return Response({})

tests/test_extend_schema.yml

@@ -123,6 +123,12 @@ components:
           items:
             $ref: '#/components/schemas/Inline'
           readOnly: true
+        field_l:
+          enum:
+          - a
+          - b
+          type: string
+          readOnly: true
     Inline:
       type: object
       properties:

tests/test_plumbing.py

@@ -0,0 +1,32 @@
+from django.db import models
+from rest_framework import serializers
+
+from drf_spectacular.plumbing import is_serializer, force_instance, is_field
+
+
+def test_is_serializer():
+    assert not is_serializer(serializers.SlugField)
+    assert not is_serializer(serializers.SlugField())
+
+    assert not is_serializer(models.CharField)
+    assert not is_serializer(models.CharField())
+
+    assert is_serializer(serializers.Serializer)
+    assert is_serializer(serializers.Serializer())
+
+
+def test_is_field():
+    assert is_field(serializers.SlugField)
+    assert is_field(serializers.SlugField())
+
+    assert not is_field(models.CharField)
+    assert not is_field(models.CharField())
+
+    assert not is_field(serializers.Serializer)
+    assert not is_field(serializers.Serializer())
+
+
+def test_force_instance():
+    assert isinstance(force_instance(serializers.CharField), serializers.CharField)
+    assert force_instance(5) == 5
+    assert force_instance(dict) == dict