AutoSchema schema.get_operation missing positional argument

[vabene1111]

Running Django 3.2, DRF: 3.12.4, Python 3.8 on Windows 10

---

I have an api where certain list endpoints can have optional get query parameters for filtering. I want to document those properly so they show up nicely in the open api doc and redoc visualization.

I have spend the last few hours reading up on this and reverse engineering the openapi generator class and all methods involved in the generation of the docs. I also read all Issues and discussions i could find in this repo. I found the following

The manual_fields that were supported by coreapi have been removed in favor of overwriting the AutoSchema methods.
As instructed by @carltongibson in #6992 (comment) i did the following (simplified during debugging, neither the original nor anything in between works)

from rest_framework.schemas.openapi import AutoSchema

# custom AutoSchema
class TestSchema(AutoSchema):
    def get_operation(self, path, method):
        return super().get_operation(path, method)

# my viewset
class RecipeViewSet(viewsets.ModelViewSet):
    ...
    schema=TestSchema

The openapi schema is generated dynamically by this url

path('openapi/', get_schema_view(title="Django Recipes", version=VERSION_NUMBER, public=True, permission_classes=(permissions.AllowAny,)), name='openapi-schema')

# I also tried the following two variants as the public attribute is checked in the failing function
path('openapi/', get_schema_view(title="Django Recipes", version=VERSION_NUMBER), name='openapi-schema')

path('openapi/', get_schema_view(title="Django Recipes", version=VERSION_NUMBER, public=False, permission_classes=(permissions.AllowAny,)), name='openapi-schema')

As soon as I assign this schema to the RecipeViewSet I get the following error.

Internal Server Error: /openapi/
Traceback (most recent call last):
  File "F:\Developement\Django\recipes\venv\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\django\views\decorators\csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\django\views\generic\base.py", line 70, in view
    return self.dispatch(request, *args, **kwargs)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\rest_framework\views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\rest_framework\schemas\views.py", line 48, in handle_exception
    return super().handle_exception(exc)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\rest_framework\views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\rest_framework\views.py", line 480, in raise_uncaught_exception
    raise exc
  File "F:\Developement\Django\recipes\venv\lib\site-packages\rest_framework\views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\rest_framework\schemas\views.py", line 37, in get
    schema = self.schema_generator.get_schema(request, self.public)
  File "F:\Developement\Django\recipes\venv\lib\site-packages\rest_framework\schemas\openapi.py", line 81, in get_schema
    operation = view.schema.get_operation(path, method)
TypeError: get_operation() missing 1 required positional argument: 'method'
[18/Apr/2021 13:46:47] "GET /openapi/ HTTP/1.1" 500 135208
[18/Apr/2021 13:46:48] "GET /service-worker.js HTTP/1.1" 200 45295

I have tried many different variations, dumming down the Viewset by removing all but the absolutely necessary parameters and methods but nothing seems to work. Is this a bug or do i need to inherit another Class/implement another method ?

During my search i have found countless examples of people struggling to do this very simple thing: document query parameters. I think a small and clear example on how to do this would be really really helpful to a lot of people.

Thanks for the help and also thanks for this awesome framework, once some things are understood it is a real pleasure to use and does so many things just awesomly right.

[carltongibson]

TypeError: get_operation() missing 1 required positional argument: 'method'

Did you assign your AutoSchema class, rather than an instance? (Otherwise I can’t see from what you have here, why the correct parameters wouldn’t be passed.)

[vabene1111]

I am sorry, re read the post 3 times but missed that i did not put the schema class in.

Yes i assigned it as the class (updated above).

Thanks for the super fast response, if you have no idea whats wrong i will create a minimal django project and verify that the issue persists there as well.

[carltongibson]

schema should be an instance

[vabene1111]

EDIT:
Read your answer after posting, thank you, works with an instance. Just assumed it would be a class since many other of the properties are. Thank you very much!

---

Old answer, now just a working example

Ok so i have created a new project (same versions of all dependencies)

views.py

from django.contrib.auth.models import User

from rest_framework import viewsets, serializers
from rest_framework.schemas.openapi import AutoSchema


class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('last_name', 'first_name')


class TestSchema(AutoSchema):
    def get_operation(self, path, method):
        return super().get_operation(path, method)


class UserViewSet(viewsets.ModelViewSet):
    model = User
    queryset = User.objects.all()
    serializer_class = UserSerializer
    schema = TestSchema()

urls.py

from django.contrib import admin
from django.urls import path, include
from rest_framework import routers
from rest_framework.schemas import get_schema_view

from drftest import views

router = routers.DefaultRouter()
router.register(r'user', views.UserViewSet, basename='user')


urlpatterns = [
    path('admin/', admin.site.urls),
    path('openapi/', get_schema_view(title="Test", version='0.1.0'), name='openapi-schema'),
    path('api/', include((router.urls, 'api'))),
]

It results in exactly the same issue when trying to access /openapi/

Internal Server Error: /openapi/
Traceback (most recent call last):
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\django\core\handlers\base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\django\views\decorators\csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\django\views\generic\base.py", line 70, in view
    return self.dispatch(request, *args, **kwargs)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\rest_framework\views.py", line 509, in dispatch
    response = self.handle_exception(exc)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\rest_framework\schemas\views.py", line 48, in handle_exception
    return super().handle_exception(exc)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\rest_framework\views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\rest_framework\views.py", line 480, in raise_uncaught_exception
    raise exc
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\rest_framework\views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\rest_framework\schemas\views.py", line 37, in get
    schema = self.schema_generator.get_schema(request, self.public)
  File "F:\Developement\Django\drf_test_project\venv\lib\site-packages\rest_framework\schemas\openapi.py", line 81, in get_schema
    operation = view.schema.get_operation(path, method)
TypeError: get_operation() missing 1 required positional argument: 'method'
[18/Apr/2021 14:20:33] "GET /openapi/ HTTP/1.1" 500 107456
Not Found: /service-worker.js
[18/Apr/2021 14:20:34] "GET /service-worker.js HTTP/1.1" 404 2258

[vabene1111]

For everyone in the future looking to document query parameters with django rest framework and openapi this is a working minimal example. Thanks to DRF Team for the awesome and super fast help and cool library

from rest_framework.schemas.openapi import AutoSchema
from rest_framework.schemas.utils import is_list_view

class CustomSchema(AutoSchema):

    def get_path_parameters(self, path, method):
        if not is_list_view(path, method, self.view):
            return []

        parameters = super().get_path_parameters(path, method)
        parameters.append(
            {
                "name": 'query',
                "in": "query",
                "required": False,
                "description": 'description',
                'schema': {
                    'type': 'string',  # TODO: integer, pattern, ...
                },
            }
        )
        return parameters

class RecipeViewSet(viewsets.ModelViewSet):
    schema=CustomSchema()