Add ability to set Schema fields through the serializer Meta class (#134)

* Add swagger_schema_fields attribute to serializer Meta class
* Add documentation

Closes #132.

docs/changelog.rst

@@ -3,6 +3,18 @@ Changelog
 #########
 
 
+*********
+**1.8.0**
+*********
+
+*Release date: Jun 01, 2018*
+
+- **ADDED:** added a :ref:`swagger_schema_fields <swagger_schema_fields>` field on serializer ``Meta`` classes for
+  customizing schema generation
+- **FIXED:** error responses from schema views are now rendered with ``JSONRenderer`` instead of throwing
+  confusing errors (:pr:`130`, :issue:`58`)
+- **FIXED:** ``readOnly`` schema fields will now no longer be marked as ``required`` (:pr:`133`)
+
 *********
 **1.7.4**
 *********

docs/custom_spec.rst

@@ -169,13 +169,19 @@ You can define some per-serializer options by adding a ``Meta`` class to your se
       class Meta:
          ... options here ...
 
-Currently, the only option you can add here is
+.. _swagger_schema_fields:
+
+The available options are:
 
    * ``ref_name`` - a string which will be used as the model definition name for this serializer class; setting it to
      ``None`` will force the serializer to be generated as an inline model everywhere it is used. If two serializers
      have the same ``ref_name``, both their usages will be replaced with a reference to the same definition.
      If this option is not specified, all serializers have an implicit name derived from their class name, minus any
      ``Serializer`` suffix (e.g. ``UserSerializer`` -> ``User``, ``SerializerWithSuffix`` -> ``SerializerWithSuffix``)
+   * ``swagger_schema_fields`` - a dictionary mapping :class:`.Schema` field names to values. These attributes
+     will be set on the :class:`.Schema` object generated from the ``Serializer``. Field names must be python values,
+     which are converted to Swagger ``Schema`` attribute names according to :func:`.make_swagger_name`.
+     Attribute names and values must conform to the `OpenAPI 2.0 specification <https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#schemaObject>`_.
 
 
 *************************

src/drf_yasg/inspectors/field.py

@@ -22,12 +22,39 @@ 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)
+        result = self.probe_field_inspectors(serializer, openapi.Schema, self.use_definitions)
+        schema = openapi.resolve_ref(result, self.components)
+        self.add_manual_fields(serializer, schema)
+        return result
+
+    def add_manual_parameters(self, serializer, parameters):
+        """Add/replace parameters from the given list of automatically generated request parameters. This method
+        is called only when the serializer is converted into a list of parameters for use in a form data request.
+
+        :param serializer: serializer instance
+        :param list[openapi.Parameter] parameters: genereated parameters
+        :return: modified parameters
+        :rtype: list[openapi.Parameter]
+        """
+        return parameters
 
     def get_request_parameters(self, serializer, in_):
         fields = getattr(serializer, 'fields', {})
-        return [
+        parameters = [
             self.probe_field_inspectors(
                 value, openapi.Parameter, self.use_definitions,
                 name=self.get_parameter_name(key), in_=in_
@@ -36,12 +63,17 @@ class InlineSerializerInspector(SerializerInspector):
             in fields.items()
         ]
 
+        return self.add_manual_parameters(serializer, parameters)
+
     def get_property_name(self, field_name):
         return field_name
 
     def get_parameter_name(self, field_name):
         return field_name
 
+    def get_serializer_ref_name(self, serializer):
+        return get_serializer_ref_name(serializer)
+
     def field_to_swagger_object(self, field, swagger_object_type, use_references, **kwargs):
         SwaggerType, ChildSwaggerType = self._get_partial_types(field, swagger_object_type, use_references, **kwargs)
 
@@ -55,7 +87,7 @@ class InlineSerializerInspector(SerializerInspector):
             if swagger_object_type != openapi.Schema:
                 raise SwaggerGenerationError("cannot instantiate nested serializer as " + swagger_object_type.__name__)
 
-            ref_name = get_serializer_ref_name(field)
+            ref_name = self.get_serializer_ref_name(field)
 
             def make_schema_definition():
                 properties = OrderedDict()

testproj/todo/serializer.py

@@ -1,3 +1,5 @@
+from collections import OrderedDict
+
 from django.utils import timezone
 from rest_framework import serializers
 from rest_framework_recursive.fields import RecursiveField
@@ -26,6 +28,15 @@ class TodoYetAnotherSerializer(serializers.ModelSerializer):
         model = TodoYetAnother
         fields = ('title', 'todo')
         depth = 2
+        swagger_schema_fields = {
+            'example': OrderedDict([
+                ('title', 'parent'),
+                ('todo', OrderedDict([
+                    ('title', 'child'),
+                    ('todo', None),
+                ])),
+            ])
+        }
 
 
 class TodoTreeSerializer(serializers.ModelSerializer):

tests/reference.yaml

@@ -1578,6 +1578,11 @@ definitions:
                 minLength: 1
             readOnly: true
         readOnly: true
+    example:
+      title: parent
+      todo:
+        title: child
+        todo: null
   UserSerializerrr:
     required:
       - username