Question

我有一个模特，像这样：

    name = models.CharField(max_length=255)
    modify_time = models.DateTimeField(auto_now=True)
    chasha = models.CharField(max_length=255)
    stat = models.CharField(max_length=255)

通常，＆＃39; modify_time＆＃39;将在我更新名称＆＃39;，＆＃39; chasha＆＃39;，＆＃39; stat＆＃39;时更新领域。但是，我只是不想要＆＃39; modify_time＆＃39;我更新了＆＃39; stat＆＃39;时已更新。我怎么能这样做？

感谢。

Answer 1

使用自定义保存方法通过查看上一个实例来更新字段。

from django.db import models
from django.utils import timezone as tz


class MyModel(models.Model):
    name = models.CharField(max_length=255)
    modify_time = models.DateTimeField(null=True, blank=True)
    chasha = models.CharField(max_length=255)
    stat = models.CharField(max_length=255)

    def save(self, *args, **kwargs):
        if self.pk: # object already exists in db
            old_model = MyModel.objects.get(pk=self.pk)
            for i in ('name', 'chasha'): # check for name or chasha changes
                if getattr(old_model, i, None) != getattr(self, i, None):
                    self.modify_time = tz.now() # assign modify_time
        else: 
             modify_time = tz.now() # if new save, write modify_time
        super(MyModel, self).save(*args, **kwargs) # call the inherited save method

修改：如上所述从auto_now删除modify_time，否则将在保存方法中设置。

django＆＃39; auto_now＆＃39;忽略指定字段的更新

1 个答案: