django rest framework如何实现nest field显示，如何保存有外键的字段更新

class VersionPoolSerializer(serializers.ModelSerializer):
site_name = serializers.ReadOnlyField(source='site_name.name')
dep_version = DeployPoolSerializer(many=True, required=False, read_only=True)
create_user = serializers.ReadOnlyField(source='create_user.username')

class Meta:
model = VersionPool
fields = ('id', 'name', 'site_name', 'dep_version', 'create_user', 'add_date')

class VersionPoolViewSet(viewsets.ModelViewSet):
"""
This viewset automatically provides `list`, `create`, `retrieve`,
`update` and `destroy` actions.

Additionally we also provide an extra `highlight` action.
"""
queryset = VersionPool.objects.all()
serializer_class = VersionPoolSerializer
authentication_classes = (TokenAuthentication,)
paginate_by = 10

def get_queryset(self):
print (self.request.user, '##################')
print(self.request.auth, '##################')
queryset = self.queryset
return queryset

def create(self, request, *args, **kwargs):
name = request.data['name']
site_name = request.data['site_name']
validated_data = dict()
validated_data['name'] = site_name + "-" + name
validated_data['site_name'] = Site.objects.get(name=site_name)
validated_data['create_user'] = request.user
try:
VersionPool.objects.create(**validated_data)
response_data = {
'name': site_name + "-" + name,
'create_user': request.user.username,
'message': 'version item save success.'
}
return Response(response_data, status=status.HTTP_201_CREATED)
except:
response_data = {
'name': site_name + "-" + name,
'create_user': request.user.username,
'message': 'version item save failed.'
}
return Response(response_data, status=status.HTTP_400_BAD_REQUEST)