./manage.py generateschema: AttributeError: 'NoneType' object has no attribute 'query_params'

[bradydean]

My app injects a request query parameter value into serializer context and generateschema cannot handle this because it does not mock Request.

This is the section of code it cannot handle:

class TicketViewSet(
    mixins.CreateModelMixin, mixins.RetrieveModelMixin, viewsets.GenericViewSet
):
    lookup_field = "ticket_id"

    def get_serializer_context(self):
        """Add ticket ID and tenant ID to serializer."""

        # TODO: Fill in tenant ID from appropriate source

        context = {
            "tenant_id": 1,
            "ticket_id": self.kwargs.get("ticket_id") or str(uuid4()),
        }

        if "referenced_standard_program_ticket" in self.request.query_params:

            try:
                UUID(self.request.query_params["referenced_standard_program_ticket"])
            except ValueError:
                raise exceptions.ValidationError(
                    "Referenced standard program ticket must be a UUID."
                )

            context["referenced_standard_program_ticket"] = self.request.query_params[
                "referenced_standard_program_ticket"
            ]

        return context

This is the full traceback:

Traceback (most recent call last):
  File "/home/brady/docker-dev-env/src/ticketing-service/django_ticketing_service/./manage.py", line 22, in <module>
    main()
  File "/home/brady/docker-dev-env/src/ticketing-service/django_ticketing_service/./manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/django/core/management/__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/django/core/management/__init__.py", line 413, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/django/core/management/base.py", line 354, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/django/core/management/base.py", line 398, in execute
    output = self.handle(*args, **options)
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/rest_framework/management/commands/generateschema.py", line 41, in handle
    schema = generator.get_schema(request=None, public=True)
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/rest_framework/schemas/openapi.py", line 81, in get_schema
    operation = view.schema.get_operation(path, method)
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/rest_framework/schemas/openapi.py", line 159, in get_operation
    operation['responses'] = self.get_responses(path, method)
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/rest_framework/schemas/openapi.py", line 651, in get_responses
    serializer = self.get_serializer(path, method)
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/rest_framework/schemas/openapi.py", line 610, in get_serializer
    return view.get_serializer()
  File "/home/brady/.envs/ticketing-service/lib/python3.10/site-packages/rest_framework/generics.py", line 109, in get_serializer
    kwargs.setdefault('context', self.get_serializer_context())
  File "/home/brady/docker-dev-env/src/ticketing-service/django_ticketing_service/ticketing/views.py", line 88, in get_serializer_context
    if "referenced_standard_program_ticket" in self.request.query_params:
AttributeError: 'NoneType' object has no attribute 'query_params'

I think this is where a mock Request object could be set on the view.

django-rest-framework/rest_framework/schemas/openapi.py

Lines 610 to 623 in 00cd4ef

	def get_serializer(self, path, method):
	view = self.view
	if not hasattr(view, 'get_serializer'):
	return None
	try:
	return view.get_serializer()
	except exceptions.APIException:
	warnings.warn('{}.get_serializer() raised an exception during '
	'schema generation. Serializer fields will not be '
	'generated for {} {}.'
	.format(view.__class__.__name__, method, path))
	return None

[bradydean]

I was able to fix this by using a custom implementation of SchemaGenerator.

class MockedSchemaGenerator(SchemaGenerator):

    def get_schema(self, request=None, public=False):

        mock_request = Request(HttpRequest())
        mock_request.auth = ...

        return super().get_schema(request=mock_request, public=False)

Note the public=False part, it's very important.