GenericForeignKey problem

[ulladimil]

Hi, i use GenericForeignKey in my project and get the following error:

Traceback (most recent call last):
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/core/handlers/exception.py", line 35, in inner
    response = get_response(request)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/core/handlers/base.py", line 128, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/rest_framework/viewsets.py", line 103, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/rest_framework/views.py", line 483, in dispatch
    response = self.handle_exception(exc)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/rest_framework/views.py", line 443, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/rest_framework/views.py", line 480, in dispatch
    response = handler(request, *args, **kwargs)
  File "/home/develop21/projects/eds_vodokanal_rnd/project/views.py", line 59, in list
    return Response(serializer.data)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/rest_framework/serializers.py", line 765, in data
    ret = super(ListSerializer, self).data
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/rest_framework/serializers.py", line 262, in data
    self._data = self.to_representation(self.instance)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/rest_framework/serializers.py", line 683, in to_representation
    self.child.to_representation(item) for item in iterable
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/db/models/query.py", line 272, in __iter__
    self._fetch_all()
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/db/models/query.py", line 1182, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/db/models/query.py", line 63, in __iter__
    obj = model_cls.from_db(db, init_list, row[model_fields_start:model_fields_end])
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/db/models/base.py", line 507, in from_db
    new = cls(*values)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/db/models/base.py", line 497, in __init__
    post_init.send(sender=cls, instance=self)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/dispatch/dispatcher.py", line 178, in send
    for receiver in self._live_receivers(sender)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/django/dispatch/dispatcher.py", line 178, in <listcomp>
    for receiver in self._live_receivers(sender)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/fieldsignals/signals.py", line 79, in post_init_closure
    self.get_and_update_changed_fields(receiver, instance, fields)
  File "/home/develop21/projects/eds_vodokanal_rnd/.venv/lib/python3.6/site-packages/fieldsignals/signals.py", line 137, in get_and_update_changed_fields
    if field.attname in deferred_fields:
AttributeError: 'GenericForeignKey' object has no attribute 'attname'

• Django==2.0.10
• django-fieldsignals==0.4.0

# models.py

class Comment(models.Model):

    object_id = models.PositiveIntegerField()

    object_ct = models.ForeignKey(
        'contenttypes.ContentType',
        on_delete=models.PROTECT)

    object_nk = GenericForeignKey('object_ct', 'object_id')