Question

在不使用信号的情况下，在模型保存方法中是否可以检查是创建模型还是更新？如果是这样的话？

def save(self, force_insert=False, force_update=False, *args, **kwargs):
        """
        Override of save() method which is executed the same
        time the ``pre_save``-signal would be
        """

        models.Model.save(self, *args, **kwargs)

Answer 1

您可以检查是否已创建主键（即不是无）：

def save(self, force_insert=False, force_update=False, *args, **kwargs):

    if self.pk is None:
        # model is going to be created
    else:
        # model will be updated

    super(YourModelClass, self).save(*args, **kwargs)

注意：当您只检查if id:时，如果False的值为id，则会将其视为0。看看这个：

>>> id = 0
>>> if id:
...     print("ID is set to %s" % id)
... # no result, but the value is set!

>>> id = 1
>>> if id:
...     print("ID is set to %s" % id)
...
ID is set to 1

>>> id = 0
>>> if id is not None:
...     print("ID is set to %s" % id)
...
ID is set to 0

Answer 2

试试这个，

def save(self, force_insert=False, force_update=False, *args, **kwargs):

   if self.id:
      # updated
   else:
      # inserted

   models.Model.save(self, *args, **kwargs)

Django如何检查是否正在创建模型或更新

2 个答案: