Add distinction between request and response serializers for OpenAPI (#7424)

* Add distinction between request and response serializers

* Add docs

* document new functions in schemas.md

* add a test case for different request vs response objects

* Correct formatting for flake8

Co-authored-by: Shaun Gosse <shaun.gosse@emburse.com>

docs/api-guide/schemas.md

@@ -375,6 +375,20 @@ operationIds.
 In order to work around this, you can override `get_operation_id_base()` to
 provide a different base for name part of the ID.
 
+#### `get_serializer()`
+
+If the view has implemented `get_serializer()`, returns the result.
+
+#### `get_request_serializer()`
+
+By default returns `get_serializer()` but can be overridden to
+differentiate between request and response objects.
+
+#### `get_response_serializer()`
+
+By default returns `get_serializer()` but can be overridden to
+differentiate between request and response objects.
+
 ### `AutoSchema.__init__()` kwargs
 
 `AutoSchema` provides a number of `__init__()` kwargs that can be used for

rest_framework/schemas/openapi.py

@@ -192,15 +192,22 @@ class AutoSchema(ViewInspector):
         if method.lower() == 'delete':
             return {}
 
-        serializer = self.get_serializer(path, method)
+        request_serializer = self.get_request_serializer(path, method)
+        response_serializer = self.get_response_serializer(path, method)
 
-        if not isinstance(serializer, serializers.Serializer):
+        components = {}
-            return {}
 
-        component_name = self.get_component_name(serializer)
+        if isinstance(request_serializer, serializers.Serializer):
+            component_name = self.get_component_name(request_serializer)
+            content = self.map_serializer(request_serializer)
+            components.setdefault(component_name, content)
 
-        content = self.map_serializer(serializer)
+        if isinstance(response_serializer, serializers.Serializer):
-        return {component_name: content}
+            component_name = self.get_component_name(response_serializer)
+            content = self.map_serializer(response_serializer)
+            components.setdefault(component_name, content)
+
+        return components
 
     def _to_camel_case(self, snake_str):
         components = snake_str.split('_')
@@ -615,6 +622,20 @@ class AutoSchema(ViewInspector):
                           .format(view.__class__.__name__, method, path))
             return None
 
+    def get_request_serializer(self, path, method):
+        """
+        Override this method if your view uses a different serializer for
+        handling request body.
+        """
+        return self.get_serializer(path, method)
+
+    def get_response_serializer(self, path, method):
+        """
+        Override this method if your view uses a different serializer for
+        populating response data.
+        """
+        return self.get_serializer(path, method)
+
     def _get_reference(self, serializer):
         return {'$ref': '#/components/schemas/{}'.format(self.get_component_name(serializer))}
 
@@ -624,7 +645,7 @@ class AutoSchema(ViewInspector):
 
         self.request_media_types = self.map_parsers(path, method)
 
-        serializer = self.get_serializer(path, method)
+        serializer = self.get_request_serializer(path, method)
 
         if not isinstance(serializer, serializers.Serializer):
             item_schema = {}
@@ -648,7 +669,7 @@ class AutoSchema(ViewInspector):
 
         self.response_media_types = self.map_renderers(path, method)
 
-        serializer = self.get_serializer(path, method)
+        serializer = self.get_response_serializer(path, method)
 
         if not isinstance(serializer, serializers.Serializer):
             item_schema = {}

tests/schemas/test_openapi.py

@@ -712,6 +712,91 @@ class TestOperationIntrospection(TestCase):
         operationId = inspector.get_operation_id(path, method)
         assert operationId == 'listItem'
 
+    def test_different_request_response_objects(self):
+        class RequestSerializer(serializers.Serializer):
+            text = serializers.CharField()
+
+        class ResponseSerializer(serializers.Serializer):
+            text = serializers.BooleanField()
+
+        class CustomSchema(AutoSchema):
+            def get_request_serializer(self, path, method):
+                return RequestSerializer()
+
+            def get_response_serializer(self, path, method):
+                return ResponseSerializer()
+
+        path = '/'
+        method = 'POST'
+        view = create_view(
+            views.ExampleGenericAPIView,
+            method,
+            create_request(path),
+        )
+        inspector = CustomSchema()
+        inspector.view = view
+
+        components = inspector.get_components(path, method)
+        assert components == {
+            'Request': {
+                'properties': {
+                    'text': {
+                        'type': 'string'
+                    }
+                },
+                'required': ['text'],
+                'type': 'object'
+            },
+            'Response': {
+                'properties': {
+                    'text': {
+                        'type': 'boolean'
+                    }
+                },
+                'required': ['text'],
+                'type': 'object'
+            }
+        }
+
+        operation = inspector.get_operation(path, method)
+        assert operation == {
+            'operationId': 'createExample',
+            'description': '',
+            'parameters': [],
+            'requestBody': {
+                'content': {
+                    'application/json': {
+                        'schema': {
+                            '$ref': '#/components/schemas/Request'
+                        }
+                    },
+                    'application/x-www-form-urlencoded': {
+                        'schema': {
+                            '$ref': '#/components/schemas/Request'
+                        }
+                    },
+                    'multipart/form-data': {
+                        'schema': {
+                            '$ref': '#/components/schemas/Request'
+                        }
+                    }
+                }
+            },
+            'responses': {
+                '201': {
+                    'content': {
+                        'application/json': {
+                            'schema': {
+                                '$ref': '#/components/schemas/Response'
+                            }
+                        }
+                    },
+                    'description': ''
+                }
+            },
+            'tags': ['']
+        }
+
     def test_repeat_operation_ids(self):
         router = routers.SimpleRouter()
         router.register('account', views.ExampleGenericViewSet, basename="account")