为什么django-q抛出带有箭头时间的异常

Question

我正在尝试创建一个Django-q时间表，并按照文档在下一次运行中使用arrow，我得到了关于时间表的以下错误：

schedule(
        func='test.tasks.test_task',
        name='test_task_nightly',
        schedule_type=Schedule.DAILY,
        next_run=arrow.utcnow().replace(hour=23, minute=30),
        q_options={'timeout': 10800, 'max_attempts': 1},
    )

Traceback (most recent call last):
  File "/usr/lib/python3.8/code.py", line 90, in runcode
    exec(code, self.locals)
  File "<console>", line 1, in <module>
    schedule(
  File "/home/user/PycharmProjects/app/venv/lib/python3.8/site-packages/django_q/tasks.py", line 122, in schedule
    s.full_clean()
  File "/home/user/PycharmProjects/app/venv/lib/python3.8/site-packages/django/db/models/base.py", line 1209, in full_clean
    self.clean_fields(exclude=exclude)
  File "/home/user/PycharmProjects/app/venv/lib/python3.8/site-packages/django/db/models/base.py", line 1251, in clean_fields
    setattr(self, f.attname, f.clean(raw_value, self))
  File "/home/user/PycharmProjects/app/venv/lib/python3.8/site-packages/django/db/models/fields/__init__.py", line 650, in clean
    value = self.to_python(value)
  File "/home/user/PycharmProjects/app/venv/lib/python3.8/site-packages/django/db/models/fields/__init__.py", line 1318, in to_python
    parsed = parse_datetime(value)
  File "/home/user/PycharmProjects/app/venv/lib/python3.8/site-packages/django/utils/dateparse.py", line 107, in parse_datetime
    match = datetime_re.match(value)
TypeError: expected string or bytes-like object

不知道为什么它不接受类似于django-q文档页面中给出的示例的时间格式。

编辑:正在调度的任务：

def test_task():
    print('Executed test task')

没有太复杂的东西，只是为了测试目的

Answer 1

箭头对象模拟Python的datetime对象接口，但它们不是真正的datetime对象。因此，如果任何接收Arrow对象的代码显式检查您的值是否是诚实到良好的datetime，那么它都将失败。这正是django.db.models.fields.DateTimeField.to_python中的代码所做的事情：

def to_python(self, value):
    if value is None:
        return value
    if isinstance(value, datetime.datetime):
        return value
    if isinstance(value, datetime.date):
        value = datetime.datetime(value.year, value.month, value.day)
    ...
    try:
        parsed = parse_datetime(value)

正如您所看到的，当它与datetime或date实例不匹配时，Django将其交给parse_datetime()函数处理，该函数需要一个字符串。这解释了你的错误：TypeError: expected string or bytes-like object

您可以通过获取.datetime属性来解决此问题，该属性将返回一个普通的旧式python datetime，即

schedule(
        func='test.tasks.test_task',
        name='test_task_nightly',
        schedule_type=Schedule.DAILY,
        next_run=arrow.utcnow().replace(hour=23, minute=30).datetime,
        q_options={'timeout': 10800, 'max_attempts': 1},
    )