DRF Serializer failing until app server restart

Using Django Mystery Errors
1

Whilst this relates to DRF and is not strictly a django question, it is certainly a mystery error, so I hope you don’t mind me asking here.

I have an issue with a django web application DRF ListAPIView endpoint . The endpoint manages to return the requested data successfully for a couple of weeks to a month, but then, after a while, it raises an exception. The endpoint will continue to raise this exception every call after the initial failure, until the app server (currently using nginx-unit but also observed the same behavior with uWSGI) is restarted.

Configuration:

  • Django v 5.0.12
  • djangorestframework V 3.15.2
  • nginx-unit 1.34.2

Issue Detail:

When the endpoint fails it returns an: "AttributeError
‘QuerySet’ object has no attribute ‘bind’" exception from the ListSerializer __init__ method:

Code

The code for the api endpoints is:

class DailySummaryNop(ListAPIView):
    """"""

    serializer_class = SummaryNopSerializer

    def get_queryset(self):
        """
        """
        live_time = dt.datetime.now(dt.timezone.utc)
        number_of_days = LiveNopViewPeriod.objects.get(name="Current").summary_period
        local_time = (
            live_time.replace(minute=0)
            .replace(second=0)
            .replace(microsecond=0)
            .astimezone(LOCAL_TIMEZONE)
        )
        if local_time.hour == 23:
            efa_time = local_time + dt.timedelta(days=1)
        else:
            efa_time = local_time
        efa_end_date = efa_time.date()
        efa_start_date = efa_time - dt.timedelta(number_of_days)
        filter_data = SummaryNop.objects.filter(
            efa_date__gte=efa_start_date, efa_date__lte=efa_end_date
        ).order_by("efa_date")
        return filter_data

and the serializer is:

class SummaryNopSerializer(serializers.ModelSerializer):
    """
    """

    class Meta:
        model = SummaryNop
        fields = "__all__"

Error Traceback

Traceback (most recent call last):
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
               ^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/django/core/handlers/base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/sentry_sdk/integrations/django/views.py", line 84, in sentry_wrapped_callback
    return callback(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/django/views/decorators/csrf.py", line 65, in _view_wrapper
    return view_func(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/django/views/generic/base.py", line 104, in view
    return self.dispatch(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/views.py", line 509, in dispatch
    response = self.handle_exception(exc)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/views.py", line 469, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
    raise exc
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/views.py", line 506, in dispatch
    response = handler(request, *args, **kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/generics.py", line 203, in get
    return self.list(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/mixins.py", line 45, in list
    serializer = self.get_serializer(queryset, many=True)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/generics.py", line 114, in get_serializer
    return serializer_class(*args, **kwargs)
File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/serializers.py", line 125, in __new__
    return cls.many_init(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/serializers.py", line 161, in many_init
    return list_serializer_class(*args, **list_kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dataops/ve-trading-tagging-system/lib/python3.11/site-packages/rest_framework/serializers.py", line 607, in __init__
    self.child.bind(field_name='', parent=self)
    ^^^^^^^^^^^^^^^
AttributeError: 'QuerySet' object has no attribute 'bind'

I’m rather confused as to why the serializer object can be constructed without a bind method and why this endpoint can’t recover until the app server is restarted.

Any ideas about what might be causing this issue or how I can go about finding the root cause would be greatly appreciated. Many thanks!