refactor/bugfix PATCH & Serializer(partial=True) behaviour.

drf_spectacular/openapi.py

@@ -1,3 +1,4 @@
+import copy
 import re
 import typing
 
@@ -27,7 +28,8 @@
     build_array_type, build_basic_type, build_choice_field, build_examples_list,
     build_media_type_object, build_object_type, build_parameter_type, error, follow_field_source,
     force_instance, get_doc, get_view_model, is_basic_type, is_field, is_list_serializer,
-    is_serializer, resolve_regex_path_parameter, resolve_type_hint, safe_ref, warn,
+    is_patched_serializer, is_serializer, resolve_regex_path_parameter, resolve_type_hint, safe_ref,
+    warn,
 )
 from drf_spectacular.settings import spectacular_settings
 from drf_spectacular.types import OpenApiTypes, build_generic_type
@@ -741,9 +743,8 @@ def _map_basic_serializer(self, serializer, direction):
 
             properties[field.field_name] = safe_ref(schema)
 
-        if self.method == 'PATCH' and spectacular_settings.COMPONENT_SPLIT_PATCH:
-            if direction == 'request' and serializer.partial and not serializer.read_only:
-                required = []
+        if is_patched_serializer(serializer, direction):
+            required = []
 
         return build_object_type(
             properties=properties,
@@ -922,6 +923,10 @@ def _get_request_for_media_type(self, serializer):
             request_body_required = True
         elif is_serializer(serializer):
             if self.method == 'PATCH':
+                # we simulate what DRF is doing: the entry serializer is set to partial
+                # for PATCH requests. serializer instances received via extend_schema
+                # may be reused; prevent race conditions by modifying a copy.
+                serializer = copy.copy(serializer)
                 serializer.partial = True
             component = self.resolve_serializer(serializer, 'request')
             if not component.schema:
@@ -1106,9 +1111,8 @@ def _get_serializer_name(self, serializer, direction):
         if name.endswith('Serializer'):
             name = name[:-10]
 
-        if self.method == 'PATCH' and spectacular_settings.COMPONENT_SPLIT_PATCH:
-            if direction == 'request' and serializer.partial and not serializer.read_only:
-                name = 'Patched' + name
+        if is_patched_serializer(serializer, direction):
+            name = 'Patched' + name
 
         if direction == 'request' and spectacular_settings.COMPONENT_SPLIT_REQUEST:
             name = name + 'Request'

drf_spectacular/plumbing.py

@@ -91,6 +91,15 @@ def is_basic_type(obj, allow_none=True):
     return obj in OPENAPI_TYPE_MAPPING or obj in PYTHON_TYPE_MAPPING
 
 
+def is_patched_serializer(serializer, direction):
+    return bool(
+        spectacular_settings.COMPONENT_SPLIT_PATCH
+        and serializer.partial
+        and not serializer.read_only
+        and not (spectacular_settings.COMPONENT_SPLIT_REQUEST and direction == 'response')
+    )
+
+
 def get_lib_doc_excludes():
     # do not import on package level due to potential import recursion when loading
     # extensions as recommended:  USER's settings.py -> USER EXTENSIONS -> extensions.py

tests/test_split.py

@@ -0,0 +1,53 @@
+from unittest import mock
+
+from django.db import models
+from rest_framework import mixins, parsers, serializers, viewsets
+
+from tests import assert_schema, generate_schema
+
+
+class PNM1(models.Model):
+    field = models.IntegerField()
+
+
+class PNM2(models.Model):
+    field_relation = models.ForeignKey(PNM1, on_delete=models.CASCADE)
+
+
+class XSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = PNM1
+        fields = '__all__'
+
+
+class YSerializer(serializers.ModelSerializer):
+    field_relation = XSerializer()
+    field_relation_partial = XSerializer(source='field_relation', partial=True)
+
+    class Meta:
+        model = PNM2
+        fields = '__all__'
+
+
+class XViewset(mixins.UpdateModelMixin, viewsets.GenericViewSet):
+    parser_classes = [parsers.JSONParser]
+    serializer_class = YSerializer
+    queryset = PNM2.objects.all()
+
+
+@mock.patch('drf_spectacular.settings.spectacular_settings.COMPONENT_SPLIT_REQUEST', False)
+def test_nested_partial_on_split_request_false(no_warnings):
+    # without split request, PatchedY and Y have the same properties (minus required).
+    # PATCH only modifies outermost serializer, nested serializers must stay unaffected.
+    assert_schema(
+        generate_schema('/x/', XViewset), 'tests/test_split_request_false.yml'
+    )
+
+
+@mock.patch('drf_spectacular.settings.spectacular_settings.COMPONENT_SPLIT_REQUEST', True)
+def test_nested_partial_on_split_request_true(no_warnings):
+    # with split request, behaves like above, however response schemas are always unpatched.
+    # nested request serializers are only affected by their manual partial flag and not due to PATCH.
+    assert_schema(
+        generate_schema('/x/', XViewset), 'tests/test_split_request_true.yml'
+    )

tests/test_split_request_false.yml

@@ -0,0 +1,116 @@
+openapi: 3.0.3
+info:
+  title: ''
+  version: 0.0.0
+paths:
+  /x/{id}/:
+    put:
+      operationId: x_update
+      description: ''
+      parameters:
+      - in: path
+        name: id
+        schema:
+          type: integer
+        description: A unique integer value identifying this pn m2.
+        required: true
+      tags:
+      - x
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/Y'
+        required: true
+      security:
+      - cookieAuth: []
+      - basicAuth: []
+      - {}
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Y'
+          description: ''
+    patch:
+      operationId: x_partial_update
+      description: ''
+      parameters:
+      - in: path
+        name: id
+        schema:
+          type: integer
+        description: A unique integer value identifying this pn m2.
+        required: true
+      tags:
+      - x
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/PatchedY'
+      security:
+      - cookieAuth: []
+      - basicAuth: []
+      - {}
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Y'
+          description: ''
+components:
+  schemas:
+    PatchedX:
+      type: object
+      properties:
+        id:
+          type: integer
+          readOnly: true
+        field:
+          type: integer
+    PatchedY:
+      type: object
+      properties:
+        id:
+          type: integer
+          readOnly: true
+        field_relation:
+          $ref: '#/components/schemas/X'
+        field_relation_partial:
+          $ref: '#/components/schemas/PatchedX'
+    X:
+      type: object
+      properties:
+        id:
+          type: integer
+          readOnly: true
+        field:
+          type: integer
+      required:
+      - field
+      - id
+    Y:
+      type: object
+      properties:
+        id:
+          type: integer
+          readOnly: true
+        field_relation:
+          $ref: '#/components/schemas/X'
+        field_relation_partial:
+          $ref: '#/components/schemas/PatchedX'
+      required:
+      - field_relation
+      - field_relation_partial
+      - id
+  securitySchemes:
+    basicAuth:
+      type: http
+      scheme: basic
+    cookieAuth:
+      type: apiKey
+      in: cookie
+      name: Session

tests/test_split_request_true.yml

@@ -0,0 +1,127 @@
+openapi: 3.0.3
+info:
+  title: ''
+  version: 0.0.0
+paths:
+  /x/{id}/:
+    put:
+      operationId: x_update
+      description: ''
+      parameters:
+      - in: path
+        name: id
+        schema:
+          type: integer
+        description: A unique integer value identifying this pn m2.
+        required: true
+      tags:
+      - x
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/YRequest'
+        required: true
+      security:
+      - cookieAuth: []
+      - basicAuth: []
+      - {}
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Y'
+          description: ''
+    patch:
+      operationId: x_partial_update
+      description: ''
+      parameters:
+      - in: path
+        name: id
+        schema:
+          type: integer
+        description: A unique integer value identifying this pn m2.
+        required: true
+      tags:
+      - x
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/PatchedYRequest'
+      security:
+      - cookieAuth: []
+      - basicAuth: []
+      - {}
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Y'
+          description: ''
+components:
+  schemas:
+    PatchedXRequest:
+      type: object
+      properties:
+        field:
+          type: integer
+    PatchedYRequest:
+      type: object
+      properties:
+        field_relation:
+          $ref: '#/components/schemas/XRequest'
+        field_relation_partial:
+          $ref: '#/components/schemas/PatchedXRequest'
+    X:
+      type: object
+      properties:
+        id:
+          type: integer
+          readOnly: true
+        field:
+          type: integer
+      required:
+      - field
+      - id
+    XRequest:
+      type: object
+      properties:
+        field:
+          type: integer
+      required:
+      - field
+    Y:
+      type: object
+      properties:
+        id:
+          type: integer
+          readOnly: true
+        field_relation:
+          $ref: '#/components/schemas/X'
+        field_relation_partial:
+          $ref: '#/components/schemas/X'
+      required:
+      - field_relation
+      - field_relation_partial
+      - id
+    YRequest:
+      type: object
+      properties:
+        field_relation:
+          $ref: '#/components/schemas/XRequest'
+        field_relation_partial:
+          $ref: '#/components/schemas/PatchedXRequest'
+      required:
+      - field_relation
+      - field_relation_partial
+  securitySchemes:
+    basicAuth:
+      type: http
+      scheme: basic
+    cookieAuth:
+      type: apiKey
+      in: cookie
+      name: Session