AttributeError: object of class Schema has no attribute fields

[abhi1693]

NetBox version

v3.3.10

Python version

3.10

Steps to Reproduce

Write a ViewSet with create method. Add a swagger decorator on it as

from drf_yasg import openapi
from drf_yasg.utils import swagger_auto_schema
from rest_framework.response import Response
from rest_framework.viewsets import ViewSet
from rest_framework.permissions import IsAuthenticated

class GetViewSet(ViewSet):
  permission_classes = [IsAuthenticated]

  @swagger_auto_schema(
    request_body=openapi.Schema(
        type=openapi.TYPE_OBJECT,
        required=['my_field'],
        properties={
            'my_field': openapi.Schema(
                type=openapi.TYPE_STRING
            )
        },
    )
  )
  def create(self, request):
    return Response({'works: True})

Expected Behavior

The swagger docs page should not crash

Observed Behavior

Internal Server Error: /api/docs/
Traceback (most recent call last):
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/openapi.py", line 110, in __getattr__
    return self[make_swagger_name(item)]
KeyError: 'fields'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/core/handlers/base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/views.py", line 34, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/utils/decorators.py", line 133, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/views/decorators/vary.py", line 21, in inner_func
    response = func(*args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/views/generic/base.py", line 84, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/rest_framework/views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/rest_framework/views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
    raise exc
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/rest_framework/views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/views.py", line 94, in get
    schema = generator.get_schema(request, self.public)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/generators.py", line 248, in get_schema
    paths, prefix = self.get_paths(endpoints, components, request, public)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/generators.py", line 406, in get_paths
    operation = self.get_operation(view, path, prefix, method, components, request)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/generators.py", line 448, in get_operation
    operation = view_inspector.get_operation(operation_keys)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/inspectors/view.py", line 32, in get_operation
    body = self.get_request_body_parameters(consumes)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/inspectors/view.py", line 71, in get_request_body_parameters
    serializer = self.get_request_serializer()
  File "/home/asaharan/PycharmProjects/netbox/netbox/utilities/custom_inspectors.py", line 32, in get_request_serializer
    if writable_class := self.get_writable_class(serializer):
  File "/home/asaharan/PycharmProjects/netbox/netbox/utilities/custom_inspectors.py", line 42, in get_writable_class
    fields = {} if hasattr(serializer, 'child') else serializer.fields
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/openapi.py", line 113, in __getattr__
    raise AttributeError("object of class " + type(self).__name__ + " has no attribute " + item)
AttributeError: object of class Schema has no attribute fields
Internal Server Error: /api/docs/
Traceback (most recent call last):
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/openapi.py", line 110, in __getattr__
    return self[make_swagger_name(item)]
KeyError: 'fields'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/core/handlers/base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/views.py", line 34, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/utils/decorators.py", line 133, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/views/decorators/vary.py", line 21, in inner_func
    response = func(*args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/django/views/generic/base.py", line 84, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/rest_framework/views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/rest_framework/views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
    raise exc
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/rest_framework/views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/views.py", line 94, in get
    schema = generator.get_schema(request, self.public)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/generators.py", line 248, in get_schema
    paths, prefix = self.get_paths(endpoints, components, request, public)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/generators.py", line 406, in get_paths
    operation = self.get_operation(view, path, prefix, method, components, request)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/generators.py", line 448, in get_operation
    operation = view_inspector.get_operation(operation_keys)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/inspectors/view.py", line 32, in get_operation
    body = self.get_request_body_parameters(consumes)
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/inspectors/view.py", line 71, in get_request_body_parameters
    serializer = self.get_request_serializer()
  File "/home/asaharan/PycharmProjects/netbox/netbox/utilities/custom_inspectors.py", line 32, in get_request_serializer
    if writable_class := self.get_writable_class(serializer):
  File "/home/asaharan/PycharmProjects/netbox/netbox/utilities/custom_inspectors.py", line 42, in get_writable_class
    fields = {} if hasattr(serializer, 'child') else serializer.fields
  File "/home/asaharan/PycharmProjects/netbox/venv/lib/python3.10/site-packages/drf_yasg/openapi.py", line 113, in __getattr__
    raise AttributeError("object of class " + type(self).__name__ + " has no attribute " + item)
AttributeError: object of class Schema has no attribute fields

[abhi1693]

Here is a fix

diff --git a/netbox/utilities/custom_inspectors.py b/netbox/utilities/custom_inspectors.py
index d87613b20..25358535d 100644
--- a/netbox/utilities/custom_inspectors.py
+++ b/netbox/utilities/custom_inspectors.py
@@ -27,7 +27,7 @@ class NetBoxSwaggerAutoSchema(SwaggerAutoSchema):
     def get_request_serializer(self):
         serializer = super().get_request_serializer()
 
-        if serializer is not None and self.method in self.implicit_body_methods:
+        if serializer is not None and not isinstance(serializer, openapi.Schema) and self.method in self.implicit_body_methods:
             if writable_class := self.get_writable_class(serializer):
                 if hasattr(serializer, 'child'):
                     child_serializer = self.get_writable_class(serializer.child)

[abhi1693]

@jeremystretch Can I submit a PR for this? It's an issue on v3.4.2 as well

[jeremystretch]

Sure; thanks!