如何遍历django模型字段,并根据条件添加值

我有一个模型,它模拟了一条多达30个车站的列车线,因此该模型有30个可空字段。

模型.py

class TempLine(models.Model):
    picking_mode = models.IntegerField(default=1)
    start_station = models.CharField(max_length=2000)
    end_station = models.CharField(max_length=2000, null=True)
    station_1 = models.CharField(max_length=2000, null=True)
    station_2 = models.CharField(max_length=2000, null=True)
    station_3 = models.CharField(max_length=2000, null=True)
    station_4 = models.CharField(max_length=2000, null=True)
    station_5 = models.CharField(max_length=2000, null=True)
    station_6 = models.CharField(max_length=2000, null=True)
    station_7 = models.CharField(max_length=2000, null=True)
    station_8 = models.CharField(max_length=2000, null=True)
    station_9 = models.CharField(max_length=2000, null=True)
    station_10 = models.CharField(max_length=2000, null=True)
    station_11 = models.CharField(max_length=2000, null=True)
    station_12 = models.CharField(max_length=2000, null=True)
    station_13 = models.CharField(max_length=2000, null=True)
    station_14 = models.CharField(max_length=2000, null=True)
    station_15 = models.CharField(max_length=2000, null=True)
    station_16 = models.CharField(max_length=2000, null=True)
    station_17 = models.CharField(max_length=2000, null=True)
    station_18 = models.CharField(max_length=2000, null=True)
    station_19 = models.CharField(max_length=2000, null=True)
    station_21 = models.CharField(max_length=2000, null=True)
    station_22 = models.CharField(max_length=2000, null=True)
    station_23 = models.CharField(max_length=2000, null=True)
    station_24 = models.CharField(max_length=2000, null=True)
    station_25 = models.CharField(max_length=2000, null=True)
    station_26 = models.CharField(max_length=2000, null=True)
    station_27 = models.CharField(max_length=2000, null=True)
    station_28 = models.CharField(max_length=2000, null=True)
    station_29 = models.CharField(max_length=2000, null=True)
    station_30 = models.CharField(max_length=2000, null=True)

使用ajax请求逐个添加数据。

所以我必须从 station_1 …检查是否没有,添加..如果没有..去下一个吧。

以下是我尝试的方法:

def adding_inline_stations(request):
    in_line_station = request.GET.get('inLine_stations', None)
    obj = TempLine.objects.filter()[0]
    for f in obj._meta.get_fields[3:]:
        if f is None:
            f = in_line_station
            f.save()
        else:
            pass

返回错误的 TypeError: 'method' object is not subscriptable