Problem with view

Hello,
I'am a newbie in usign django and django rest.
I have a problem with a modelsetview
The message error is:

Exception Type:	AttributeError
Exception Value:	type object 'Fatture' has no attribute 'objects'
Exception Location:	C:\Lavoro\Python\scambiosdi\scambiosdi\fatture\api\views.py, line 15, in get_queryset

This is the model.py:
from django.db import models
from scambiosdi import dataset
from utenti.models import Utenti

class Fatture(models.Model):
    utente = models.ForeignKey(Utenti, on_delete=models.CASCADE, related_name="fatture")
    tipo_fattura = models.IntegerField(choices=dataset.TIPOFATTURA)
    denominazione = models.CharField(max_length=80)
    numero = models.CharField(max_length=20)
    data = models.DateField()
    totale = models.DecimalField(max_digits=18, decimal_places=2, default=0)
    identificativo_sdi = models.CharField(max_length=50, blank=True)
    percorso_file_originale = models.CharField(max_length=240, blank=True)
    percorso_file_pulito = models.CharField(max_length=240, blank=True)

    class Meta():
        verbose_name = 'Fattura'
        verbose_name_plural = 'Fatture'

    def __str__(self):
        return '{} {} {}'.format(self.denominazione, self.numero, self.data)

This is the serializers.py:
from rest_framework import serializers
from fatture.models import Fatture

class FatturaSerializer(serializers.ModelSerializer):
    user = serializers.StringRelatedField(read_only=True)

    class Meta:
        model = Fatture
        fields = "__all__"

And this is the views.py:
from rest_framework.viewsets import ModelViewSet
from rest_framework.permissions import IsAuthenticated
from fatture.models import Fatture
from fatture.api.serializers import FatturaSerializer

class Fatture(ModelViewSet):
    serializer_class = FatturaSerializer
    permission_classes = [IsAuthenticated]

    def get_queryset(self):
        queryset = Fatture.objects.all()
        idfattura =  self.request.query_params.get("idfattura", None)
        if idfattura is not None:
            queryset = queryset.filter(id=idfattura)
        return queryset

If I change the Fatture class in this way works correctly:
class Fatture(ModelViewSet):
    queryset = Fatture.objects.all()
    serializer_class = FatturaSerializer
    permission_classes = [IsAuthenticated]


Maurizio