如何在Djang中取整时区软件日期

Question

我试图将默认时区datetime转换为localtime，并在Django视图中将时间取整为15分钟。我有以下循环时间函数：

def roundTime(dt=None, dateDelta=timedelta(minutes=1)):
    """Round a datetime object to a multiple of a timedelta
    dt : datetime.datetime object, default now.
    dateDelta : timedelta object, we round to a multiple of this, default 1 minute.
    Author: Thierry Husson 2012 - Use it as you want but don't blame me.
            Stijn Nevens 2014 - Changed to use only datetime objects as variables
    """
    roundTo = dateDelta.total_seconds()

    if dt == None:
        dt = datetime.now()
    seconds = (dt - dt.min).seconds
    # // is a floor division, not a comment on following line:
    rounding = (seconds+roundTo/2) // roundTo * roundTo
    return dt + timedelta(0,rounding-seconds,-dt.microsecond)

以下是我迄今为止所做的努力：

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但最后一行给出了一个错误：

error: astimezone() cannot be applied to a naive datetime

当我使用：

local_time = timezone.localtime(timezone.now()) 

我确实得到了正确的当地时间，但由于某些原因，我无法通过以下方式来确定时间：

mytime = roundTime(local_time,timedelta(minutes=15)).strftime('%H:%M:%S') 

它与上面的datetime.now()一起工作。在

我想出了一个不漂亮但很有用的代码：

mytime = timezone.localtime(timezone.now())
mytime = datetime.strftime(mytime, '%Y-%m-%d %H:%M:%S')
mytime = datetime.strptime(str(mytime), '%Y-%m-%d %H:%M:%S')
mytime = roundTime(mytime,timedelta(minutes=15)).strftime('%H:%M:%S')
mytime = datetime.strptime(str(mytime), '%H:%M:%S')

有更好的解决办法吗？在

Answer 1

要舍入时区感知日期时间对象，make it a naive datetime object, round it, and attach the correct time zone info for the rounded time：

from datetime import timedelta
from django.utils import timezone

def round_time(dt=None, delta=timedelta(minutes=1)):
    if dt is None:
        dt = timezone.localtime(timezone.now()) # assume USE_TZ=True
    tzinfo, is_dst = dt.tzinfo, bool(dt.dst())
    dt = dt.replace(tzinfo=None)
    f = delta.total_seconds()
    rounded_ordinal_seconds = f * round((dt - dt.min).total_seconds() / f)
    rounded_dt = dt.min + timedelta(seconds=rounded_ordinal_seconds)
    localize = getattr(tzinfo, 'localize', None)
    if localize:
        rounded_dt = localize(rounded_dt, is_dst=is_dst)
    else:
        rounded_dt = rounded_dt.replace(tzinfo=tzinfo)
    return rounded_dt

为了避免浮点问题，可以使用整数微秒（dt.resolution）重写所有计算。在

示例：

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Answer 2

您正在使用的roundTime函数不适用于支持时区的日期。 为了支持它，您可以这样修改它：

def roundTime(dt=None, dateDelta=timedelta(minutes=1)):
    """Round a datetime object to a multiple of a timedelta
    dt : datetime.datetime object, default now.
    dateDelta : timedelta object, we round to a multiple of this, default 1 minute.
    Author: Thierry Husson 2012 - Use it as you want but don't blame me.
            Stijn Nevens 2014 - Changed to use only datetime objects as variables
    """
    roundTo = dateDelta.total_seconds()

    if dt == None : 
        dt = datetime.now()
    #Make sure dt and datetime.min have the same timezone
    tzmin = dt.min.replace(tzinfo=dt.tzinfo)

    seconds = (dt - tzmin).seconds
    # // is a floor division, not a comment on following line:
    rounding = (seconds+roundTo/2) // roundTo * roundTo
    return dt + timedelta(0,rounding-seconds,-dt.microsecond)

这样，函数就可以同时处理naiver和TZ-aware日期。 然后您可以继续进行第二次尝试：

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