Django拒绝接受FloatField的一次性默认值

Question

我有一个类，正在尝试向它添加一个新的FloatField。Django希望使用默认值填充现有行（合理）。但是，它拒绝接受我给它的任何价值。

You are trying to add a non-nullable field 'FIELDNAME' to CLASS without a default; we can't do that (the database needs something to populate existing rows).
Please select a fix:
 1) Provide a one-off default now (will be set on all existing rows with a null value for this column)
 2) Quit, and let me add a default in models.py
Select an option: -1
Please select a valid option: -1
Please select a valid option: -1
Please select a valid option: float(-1)
Please select a valid option: -1.0
Please select a valid option: float(-1.0)
Please select a valid option: 

如何让它接受我的价值？

Answer 1

您应该选择选项1，然后输入您的值

 1) Provide a one-off default now (will be set on all existing rows with a null value for this column)
 2) Quit, and let me add a default in models.py
 1

选择1后。它会要求提供默认值。

Please enter the default value now, as valid Python
The datetime and django.utils.timezone modules are available, so you can do e.g. timezone.now()
>>> -1.0