Question

我想从django 1.8将默认值传递给DurationField。根据文档，它应该是datetime.timedelta

from datetime import timedelta
pause = DurationField(default=timedelta(minutes=20))

但是关于makemigrations它说：

ValueError: Cannot serialize: datetime.timedelta(0, 1200)
There are some values Django cannot serialize into migration files.

确定。也许我们应该传递整数？

pause = DurationField(default=int(timedelta(minutes=20).total_seconds()))

或：

pause = DurationField(default=20*60)

makemigrations运行正常，但在创建对象时我看到：

for obj in self.query.objs
  File "/home/web/django_env/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 920, in <listcomp>
    for obj in self.query.objs
  File "/home/web/django_env/lib/python3.4/site-packages/django/db/models/sql/compiler.py", line 918, in <listcomp>
    ) for f in fields
  File "/home/web/django_env/lib/python3.4/site-packages/django/db/models/fields/__init__.py", line 710, in get_db_prep_save
    prepared=False)
  File "/home/web/django_env/lib/python3.4/site-packages/django/db/models/fields/__init__.py", line 1683, in get_db_prep_value
    return value.total_seconds() * 1000000
AttributeError: 'int' object has no attribute 'total_seconds'

所以它想要timedelta？

Answer 1

默认值应为timedelta。这是Django中的一个错误，并设置为在1.8.1版本中修复。请参阅：https://code.djangoproject.com/ticket/24566

所以pause = DurationField(default=timedelta(minutes=20)) 应该使用1.8.1版本。

Answer 2

你略微混淆了事情的顺序：

pause = DurationField(default=int(timedelta(minutes=20).total_seconds()))

如上所述，整数没有total_seconds()属性。相反，它是instance method of timedelta。

Django DurationField默认

2 个答案: