问django rest框架对base 10的int()无效文本：

EN

class PatientDataSerializer(serializers.ModelSerializer):
    class Meta:
        model = PatientData
        fields = (
            'data_id',
            'data_type',
            'session_id',
            'user_id',
            'start_time',
            'time_elapsed',
            'data_file_url'
        )
        lookup_field='user_id'

class PatientData(models.Model):
    class Meta:
        managed = False
        db_table = "patient_data_list"

    data_id = models.PositiveIntegerField(db_column="data_id", primary_key=True)
    data_type = models.CharField(db_column="patient_data_type", max_length=255)
    session_id = models.PositiveIntegerField(db_column="session_id")
    user_id = models.PositiveIntegerField(db_column="user_id")
    start_time = models.DateTimeField(db_column="start_time")
    time_elapsed = models.IntegerField(db_column="time_elapsed")
    data_file_url = models.IntegerField(db_column="data_file_url")  

 url(r'^patients/data/(?P<user_id>[0-9]+)/$', restapiviews.PatientDataListView.as_view()),

class PatientDataListView(generics.ListAPIView):
    queryset = PatientData.objects.all()
    serializer_class = PatientDataSerializer
    lookup_field='user_id'