Python Django保存功能模型：如何分配；数据“U计数器”；从excel文件导入时作为数字系列

这是这些问题的继续：

我有一个为每个位置id生成序列号的场景，我可以在上面的链接中解决这个问题

现在，我关心的是：

使用

django导入导出

导入excel文件时，如何将

data\u计数器

指定为序列号

到目前为止，如果我将通过管理站点添加一个新实例，

保存功能

正在按预期工作，但是当通过导入功能添加一个新实例（批量）时，一切都乱七八糟，我无法编辑整个属性号字段xD，结果如下：

如图所示，序列号是最后一组（4位）的第二个，位置id是最后一组（2位）

前9个数据应如下所示：

1972-30-40-0001-00
1972-30-40-0002-00
1972-30-40-0003-00
1972-30-40-0004-00
1972-30-40-0001-18
1972-30-40-0005-00
1972-30-40-0001-19
1972-30-40-0002-19
1972-30-40-0006-00 and so on...

保存功能

def save(self, *args, **kwargs):
    data_counter = Item.objects.filter(location=self.location).aggregate(counter=Count('id'))['counter'] # Count existing instance with matching "location id" of the new instance
    if self.pk is None and self.property_number is None: # if new instance and property number field is blank
        if data_counter is None: # if data_counter is empty/none, no matching instance
            data_counter = 1  # start at 1
        else: # else, if there is matching instance
            data_counter += 1 # add 1 to the data_counter
    elif self.pk is not None and self.property_number is None: # if not new instance and property number field is blank, Update an instance without property number
        if data_counter is None: # if data_counter is empty/none, the existing instance has no matching location id, Update
            data_counter = 1 # Existing instance start at 1
        else: # else, if there is matching instance
            data_counter += 1 # add 1 to the data_counter

    # data_counter will be the series number for every location ID
    self.property_number = '{}-{}-{:04d}-{}'.format(self.date_acquired.year, self.sub_major_group_and_gl_account.sub_major_group_and_gl_account, data_counter, self.location.location_code)
    
    super(Item, self).save(*args, **kwargs)