Python 无法比较天真和有意识的 datetime.now() <= challenge.datetime_end
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Can't compare naive and aware datetime.now() <= challenge.datetime_end
提问by sccrthlt
I am trying to compare the current date and time with dates and times specified in models using comparison operators:
我正在尝试使用比较运算符将当前日期和时间与模型中指定的日期和时间进行比较：
if challenge.datetime_start <= datetime.now() <= challenge.datetime_end:
The script errors out with:
脚本出错：
TypeError: can't compare offset-naive and offset-aware datetimes
The models look like this:
模型如下所示：
class Fundraising_Challenge(models.Model):
name = models.CharField(max_length=100)
datetime_start = models.DateTimeField()
datetime_end = models.DateTimeField()
I also have django using locale date and times.
我也有使用语言环境日期和时间的 django。
What I haven't been able to find is the format django uses for DateTimeField(). Is it naive or aware? And how do I get datetime.now() to recognize locale datetime?
我无法找到的是 django 用于 DateTimeField() 的格式。它是幼稚的还是意识到的？以及如何让 datetime.now() 识别区域设置日期时间？
采纳答案by Viren Rajput
By default, the datetimeobject is naivein Python, so you need to make both of them either naive or aware datetimeobjects. This can be done using:
默认情况下，datetime对象naive在 Python 中，因此您需要使它们都成为原始datetime对象或感知对象。这可以使用：
import datetime
import pytz
utc=pytz.UTC
challenge.datetime_start = utc.localize(challenge.datetime_start)
challenge.datetime_end = utc.localize(challenge.datetime_end)
# now both the datetime objects are aware, and you can compare them
Note: This would raise a ValueErrorif tzinfois already set. If you are not sure about that, just use
注意：这会引发一个ValueErroriftzinfo已经设置。如果您不确定，请使用
start_time = challenge.datetime_start.replace(tzinfo=utc)
end_time = challenge.datetime_end.replace(tzinfo=utc)
BTW, you could format a UNIX timestamp in datetime.datetime object with timezone info as following
顺便说一句，您可以使用时区信息在 datetime.datetime 对象中格式化 UNIX 时间戳，如下所示
d = datetime.datetime.utcfromtimestamp(int(unix_timestamp))
d_with_tz = datetime.datetime(
year=d.year,
month=d.month,
day=d.day,
hour=d.hour,
minute=d.minute,
second=d.second,
tzinfo=pytz.UTC)
回答by Alfredo Aguirre
datetime.datetime.nowis not timezone aware.
datetime.datetime.now不知道时区。
Django comes with a helper for this, which requires pytz
Django为此提供了一个帮助程序，它需要 pytz
from django.utils import timezone
now = timezone.now()
You should be able to compare nowto challenge.datetime_start
你应该能够比较now来challenge.datetime_start
回答by myusuf3
So the way I would solve this problem is to make sure the two datetimes are in the right timezone.
所以我解决这个问题的方法是确保两个日期时间在正确的时区。
I can see that you are using datetime.now()which will return the systems current time, with no tzinfo set.
我可以看到您正在使用datetime.now()它将返回系统当前时间，而没有设置 tzinfo。
tzinfo is the information attached to a datetime to let it know what timezone it is in. If you are using naive datetime you need to be consistent through out your system. I would highly recommend only using datetime.utcnow()
tzinfo 是附加到日期时间的信息，以使其知道它所在的时区。如果您使用天真的日期时间，您需要在整个系统中保持一致。我强烈建议只使用datetime.utcnow()
seeing as somewhere your are creating datetime that have tzinfo associated with them, what you need to do is make sure those are localized (has tzinfo associated) to the correct timezone.
看到您正在创建的日期时间与 tzinfo 相关联，您需要做的是确保将它们本地化（与 tzinfo 相关联）到正确的时区。
Take a look at Delorean, it makes dealing with this sort of thing much easier.
看看Delorean，它使处理此类事情变得更加容易。
回答by ePi272314
One line of code solution
一行代码解决
if timezone_aware_var <= datetime.datetime.now(timezone_aware_var.tzinfo):
pass #some code
Explained version
解释版
# Timezone info of your timezone aware variable
timezone = your_timezone_aware_variable.tzinfo
# Current datetime for the timezone of your variable
now_in_timezone = datetime.datetime.now(timezone)
# Now you can do a fair comparison, both datetime variables have the same time zone
if your_timezone_aware_variable <= now_in_timezone:
pass #some code
Summary
概括
You must add the timezone info to your now()datetime.
However, you must add the sametimezone of the reference variable; that is why I first read the tzinfoattribute.
您必须将时区信息添加到您的now()日期时间。
但是，您必须添加与引用变量相同的时区；这就是我首先阅读tzinfo属性的原因。
回答by Amin Fathi
Disable time zone.
Use challenge.datetime_start.replace(tzinfo=None);
禁用时区。用challenge.datetime_start.replace(tzinfo=None);
You can also use replace(tzinfo=None)for other datetime.
您也可以replace(tzinfo=None)用于其他日期时间。
if challenge.datetime_start.replace(tzinfo=None) <= datetime.now().replace(tzinfo=None) <= challenge.datetime_end.replace(tzinfo=None):
回答by Chandan Sharma
It is working form me. Here I am geeting the table created datetime and adding 10 minutes on the datetime. later depending on the current time, Expiry Operations are done.
这是我的工作。在这里，我正在创建表创建的日期时间并在日期时间上添加 10 分钟。稍后根据当前时间，到期操作完成。
from datetime import datetime, time, timedelta
import pytz
Added 10 minutes on database datetime
在数据库日期时间上添加了 10 分钟
table_datetime = '2019-06-13 07:49:02.832969' (example)
table_datetime = '2019-06-13 07:49:02.832969'（示例）
# Added 10 minutes on database datetime
# table_datetime = '2019-06-13 07:49:02.832969' (example)
table_expire_datetime = table_datetime + timedelta(minutes=10 )
# Current datetime
current_datetime = datetime.now()
# replace the timezone in both time
expired_on = table_expire_datetime.replace(tzinfo=utc)
checked_on = current_datetime.replace(tzinfo=utc)
if expired_on < checked_on:
print("Time Crossed)
else:
print("Time not crossed ")
It worked for me.
它对我有用。
