Make swagger_schema_fields work on serializer Fields

Closes #167.

docs/changelog.rst

@@ -52,7 +52,7 @@ Changelog
 - **ADDED:** added ``DEFAULT_GENERATOR_CLASS`` setting and ``--generator-class`` argument to the ``generate_swagger``
   management command (:issue:`140`)
 - **FIXED:** fixed wrongly required ``'count'`` response field on ``CursorPagination`` (:issue:`141`)
-- **FIXED:** fixed some cases where ``swagger_extra_fields`` would not be handlded (:pr:`142`)
+- **FIXED:** fixed some cases where ``swagger_schema_fields`` would not be handlded (:pr:`142`)
 - **FIXED:** fixed crash when encountering ``coreapi.Fields``\ s without a ``schema`` (:issue:`143`)
 
 *********

src/drf_yasg/inspectors/base.py

@@ -2,10 +2,9 @@ import inspect
 import logging
 
 from rest_framework import serializers
-from rest_framework.utils import encoders, json
 
 from .. import openapi
-from ..utils import decimal_as_float, force_real_str, is_list_view
+from ..utils import force_real_str, get_field_default, is_list_view
 
 #: Sentinel value that inspectors must return to signal that they do not know how to handle an object
 NotHandled = object()
@@ -135,6 +134,19 @@ class FieldInspector(BaseInspector):
         super(FieldInspector, self).__init__(view, path, method, components, request)
         self.field_inspectors = field_inspectors
 
+    def add_manual_fields(self, serializer_or_field, schema):
+        """Set fields from the ``swagger_schem_fields`` attribute on the Meta class. This method is called
+        only for serializers or fields that are converted into ``openapi.Schema`` objects.
+
+        :param serializer_or_field: serializer or field instance
+        :param openapi.Schema schema: the schema object to be modified in-place
+        """
+        meta = getattr(serializer_or_field, 'Meta', None)
+        swagger_schema_fields = getattr(meta, 'swagger_schema_fields', {})
+        if swagger_schema_fields:
+            for attr, val in swagger_schema_fields.items():
+                setattr(schema, attr, val)
+
     def field_to_swagger_object(self, field, swagger_object_type, use_references, **kwargs):
         """Convert a drf Serializer or Field instance into a Swagger object.
 
@@ -205,46 +217,29 @@ class FieldInspector(BaseInspector):
                 instance_kwargs['required'] = field.required
 
             if 'default' not in instance_kwargs and swagger_object_type != openapi.Items:
-                default = getattr(field, 'default', serializers.empty)
+                default = get_field_default(field)
-                if default is not serializers.empty:
+                if default not in (None, serializers.empty):
-                    if callable(default):
+                    instance_kwargs['default'] = default
-                        try:
-                            if hasattr(default, 'set_context'):
-                                default.set_context(field)
-                            default = default()
-                        except Exception:  # pragma: no cover
-                            logger.warning("default for %s is callable but it raised an exception when "
-                                           "called; 'default' field will not be added to schema", field, exc_info=True)
-                            default = None
-
-                    if default is not None:
-                        try:
-                            default = field.to_representation(default)
-                            # JSON roundtrip ensures that the value is valid JSON;
-                            # for example, sets and tuples get transformed into lists
-                            default = json.loads(json.dumps(default, cls=encoders.JSONEncoder))
-                            if decimal_as_float(field):
-                                default = float(default)
-                        except Exception:  # pragma: no cover
-                            logger.warning("'default' on schema for %s will not be set because "
-                                           "to_representation raised an exception", field, exc_info=True)
-                            default = None
-
-                    if default is not None:
-                        instance_kwargs['default'] = default
 
             if instance_kwargs.get('type', None) != openapi.TYPE_ARRAY:
                 instance_kwargs.setdefault('title', title)
-            instance_kwargs.setdefault('description', description)
+            if description is not None:
+                instance_kwargs.setdefault('description', description)
             instance_kwargs.update(kwargs)
 
             if existing_object is not None:
                 assert isinstance(existing_object, swagger_object_type)
-                for attr, val in sorted(instance_kwargs.items()):
+                for key, val in sorted(instance_kwargs.items()):
-                    setattr(existing_object, attr, val)
+                    setattr(existing_object, key, val)
-                return existing_object
+                result = existing_object
+            else:
+                result = swagger_object_type(**instance_kwargs)
 
-            return swagger_object_type(**instance_kwargs)
+            # Provide an option to add manual paremeters to a schema
+            # for example, to add examples
+            if swagger_object_type == openapi.Schema:
+                self.add_manual_fields(field, result)
+            return result
 
         # arrays in Schema have Schema elements, arrays in Parameter and Items have Items elements
         child_swagger_type = openapi.Schema if swagger_object_type == openapi.Schema else openapi.Items

src/drf_yasg/inspectors/field.py

@@ -31,19 +31,6 @@ class InlineSerializerInspector(SerializerInspector):
     #: whether to output :class:`.Schema` definitions inline or into the ``definitions`` section
     use_definitions = False
 
-    def add_manual_fields(self, serializer, schema):
-        """Set fields from the ``swagger_schem_fields`` attribute on the serializer's Meta class. This method is called
-        only for serializers that are converted into ``openapi.Schema`` objects.
-
-        :param serializer: serializer instance
-        :param openapi.Schema schema: the schema object to be modified in-place
-        """
-        serializer_meta = getattr(serializer, 'Meta', None)
-        swagger_schema_fields = getattr(serializer_meta, 'swagger_schema_fields', {})
-        if swagger_schema_fields:
-            for attr, val in swagger_schema_fields.items():
-                setattr(schema, attr, val)
-
     def get_schema(self, serializer):
         return self.probe_field_inspectors(serializer, openapi.Schema, self.use_definitions)
 
@@ -124,9 +111,6 @@ class InlineSerializerInspector(SerializerInspector):
                     # it is better to just remove title from inline models
                     del result.title
 
-                # Provide an option to add manual paremeters to a schema
-                # for example, to add examples
-                self.add_manual_fields(field, result)
                 return result
 
             if not ref_name or not use_references:
@@ -696,9 +680,9 @@ else:
                 assert use_references is True, "Can not create schema for RecursiveField when use_references is False"
 
                 ref_name = get_serializer_ref_name(field.proxied)
-                assert ref_name is not None, "Can not create RecursiveField schema for inline ModelSerializer"
+                assert ref_name is not None, "Can't create RecursiveField schema for inline " + str(type(field.proxied))
 
-                return openapi.SchemaRef(self.components.with_scope(openapi.SCHEMA_DEFINITIONS), ref_name,
+                definitions = self.components.with_scope(openapi.SCHEMA_DEFINITIONS)
-                                         ignore_unresolved=True)
+                return openapi.SchemaRef(definitions, ref_name, ignore_unresolved=True)
 
             return NotHandled

src/drf_yasg/utils.py

@@ -8,6 +8,7 @@ from rest_framework import serializers, status
 from rest_framework.mixins import DestroyModelMixin, RetrieveModelMixin, UpdateModelMixin
 from rest_framework.request import is_form_media_type
 from rest_framework.settings import api_settings as rest_framework_settings
+from rest_framework.utils import encoders, json
 from rest_framework.views import APIView
 
 logger = logging.getLogger(__name__)
@@ -354,3 +355,38 @@ def force_real_str(s, encoding='utf-8', strings_only=False, errors='strict'):
             s = '' + s
 
     return s
+
+
+def get_field_default(field):
+    """
+    Get the default value for a field, converted to a JSON-compatible value while properly handling callables.
+
+    :param field: field instance
+    :return: default value
+    """
+    default = getattr(field, 'default', serializers.empty)
+    if default is not serializers.empty:
+        if callable(default):
+            try:
+                if hasattr(default, 'set_context'):
+                    default.set_context(field)
+                default = default()
+            except Exception:  # pragma: no cover
+                logger.warning("default for %s is callable but it raised an exception when "
+                               "called; 'default' will not be set on schema", field, exc_info=True)
+                default = serializers.empty
+
+        if default is not serializers.empty:
+            try:
+                default = field.to_representation(default)
+                # JSON roundtrip ensures that the value is valid JSON;
+                # for example, sets and tuples get transformed into lists
+                default = json.loads(json.dumps(default, cls=encoders.JSONEncoder))
+                if decimal_as_float(field):
+                    default = float(default)
+            except Exception:  # pragma: no cover
+                logger.warning("'default' on schema for %s will not be set because "
+                               "to_representation raised an exception", field, exc_info=True)
+                default = serializers.empty
+
+    return default

testproj/snippets/serializers.py

@@ -23,12 +23,34 @@ class ExampleProjectSerializer(serializers.Serializer):
         ref_name = 'Project'
 
 
+class UnixTimestampField(serializers.DateTimeField):
+    def to_representation(self, value):
+        """ Return epoch time for a datetime object or ``None``"""
+        from django.utils.dateformat import format
+        try:
+            return int(format(value, 'U'))
+        except (AttributeError, TypeError):
+            return None
+
+    def to_internal_value(self, value):
+        import datetime
+        return datetime.datetime.fromtimestamp(int(value))
+
+    class Meta:
+        swagger_schema_fields = {
+            'format': 'integer',
+            'title': 'Client date time suu',
+            'description': 'Date time in unix timestamp format',
+        }
+
+
 class SnippetSerializer(serializers.Serializer):
     """SnippetSerializer classdoc
 
     create: docstring for create from serializer classdoc
     """
     id = serializers.IntegerField(read_only=True, help_text="id serializer help text")
+    created = UnixTimestampField(read_only=True)
     owner = serializers.PrimaryKeyRelatedField(
         queryset=get_user_model().objects.all(),
         default=serializers.CurrentUserDefault(),

testproj/users/serializers.py

@@ -5,7 +5,7 @@ from drf_yasg.utils import swagger_serializer_method
 from snippets.models import Snippet
 
 try:
-    import typing
+    import typing  # noqa: F401
     from .method_serializers_with_typing import MethodFieldExampleSerializer
 except ImportError:
     from .method_serializers_without_typing import MethodFieldExampleSerializer

tests/reference.yaml

@@ -947,6 +947,12 @@ definitions:
         description: id serializer help text
         type: integer
         readOnly: true
+      created:
+        title: Client date time suu
+        type: string
+        format: integer
+        readOnly: true
+        description: Date time in unix timestamp format
       owner:
         title: Owner
         description: The ID of the user that created this snippet; if none is provided,

tox.ini

@@ -57,7 +57,7 @@ exclude = **/migrations/*
 ignore = F405
 
 [isort]
-skip = .eggs,.tox,docs,env,venv
+skip = .eggs,.tox,docs,env,venv,node_modules
 skip_glob = **/migrations/*
 not_skip = __init__.py
 atomic = true