type object ‘X’ has no attribute ‘objects’

The line notifications = Notification.objects.all() is referencing the Notification View class defined in api.py and not models.py.

The easiest way to fix this error is to rename the Notification class in either api.py or models.py so that you can refer to your model properly. Another option would be to use named imports:

from .models import Notification as NotificationModel

class Notification(generics.ListAPIView):
    ...
    def get_queryset(self):
        notifications = NotificationModel.objects.all()
        ...