由于我没有看到正确的实现，我以这种方式重新编码了我的…

    def age_in_years(from_date, to_date=datetime.date.today()):
  if (DEBUG):
    logger.debug("def age_in_years(from_date='%s', to_date='%s')" % (from_date, to_date))

  if (from_date>to_date): # swap when the lower bound is not the lower bound
    logger.debug('Swapping dates ...')
    tmp = from_date
    from_date = to_date
    to_date = tmp

  age_delta = to_date.year - from_date.year
  month_delta = to_date.month - from_date.month
  day_delta = to_date.day - from_date.day

  if (DEBUG):
    logger.debug("Delta's are : %i  / %i / %i " % (age_delta, month_delta, day_delta))

  if (month_delta>0  or (month_delta==0 and day_delta>=0)): 
    return age_delta 

  return (age_delta-1)

如果你出生在2月29日，你就认为自己在2月28日是“18岁”，这是错误的。 交换边界可以省略…这只是我的代码的个人方便:)

最简单的方法是使用python-dateutil

import datetime

import dateutil

def birthday(date):
    # Get the current date
    now = datetime.datetime.utcnow()
    now = now.date()

    # Get the difference between the current date and the birthday
    age = dateutil.relativedelta.relativedelta(now, date)
    age = age.years

    return age

不幸的是，您不能只使用时间数据，因为它使用的最大单位是日，闰年将使您的计算无效。因此，让我们找到年数，然后如果最后一年没有满，就按1调整:

from datetime import date
birth_date = date(1980, 5, 26)
years = date.today().year - birth_date.year
if (datetime.now() - birth_date.replace(year=datetime.now().year)).days >= 0:
    age = years
else:
    age = years - 1

Upd:

这个解决方案在2月29日开始时确实会导致一个异常。以下是正确的检查:

from datetime import date
birth_date = date(1980, 5, 26)
today = date.today()
years = today.year - birth_date.year
if all((x >= y) for x,y in zip(today.timetuple(), birth_date.timetuple()):
   age = years
else:
   age = years - 1

Upd2:

将多次调用now()称为性能损失是荒谬的，除非在极端特殊的情况下，否则这无关紧要。使用变量的真正原因是数据不一致的风险。

下面是一个用年、月或日来计算一个人年龄的方法。

假设一个人的出生日期是2012-01-17T00:00:00 因此，他的年龄在2013-01-16T00:00:00将是11个月

或者他出生在2012-12-17T00:00:00， 他的年龄在2013-01-12T00:00:00将是26天

或者他出生在2000-02-29T00:00:00， 他的年龄在2012-02-29T00:00:00将是12岁

您将需要导入datetime。

代码如下:

def get_person_age(date_birth, date_today):

"""
At top level there are three possibilities : Age can be in days or months or years.
For age to be in years there are two cases: Year difference is one or Year difference is more than 1
For age to be in months there are two cases: Year difference is 0 or 1
For age to be in days there are 4 possibilities: Year difference is 1(20-dec-2012 - 2-jan-2013),
                                                 Year difference is 0, Months difference is 0 or 1
"""
years_diff = date_today.year - date_birth.year
months_diff = date_today.month - date_birth.month
days_diff = date_today.day - date_birth.day
age_in_days = (date_today - date_birth).days

age = years_diff
age_string = str(age) + " years"

# age can be in months or days.
if years_diff == 0:
    if months_diff == 0:
        age = age_in_days
        age_string = str(age) + " days"
    elif months_diff == 1:
        if days_diff < 0:
            age = age_in_days
            age_string = str(age) + " days"
        else:
            age = months_diff
            age_string = str(age) + " months"
    else:
        if days_diff < 0:
            age = months_diff - 1
        else:
            age = months_diff
        age_string = str(age) + " months"
# age can be in years, months or days.
elif years_diff == 1:
    if months_diff < 0:
        age = months_diff + 12
        age_string = str(age) + " months" 
        if age == 1:
            if days_diff < 0:
                age = age_in_days
                age_string = str(age) + " days" 
        elif days_diff < 0:
            age = age-1
            age_string = str(age) + " months"
    elif months_diff == 0:
        if days_diff < 0:
            age = 11
            age_string = str(age) + " months"
        else:
            age = 1
            age_string = str(age) + " years"
    else:
        age = 1
        age_string = str(age) + " years"
# The age is guaranteed to be in years.
else:
    if months_diff < 0:
        age = years_diff - 1
    elif months_diff == 0:
        if days_diff < 0:
            age = years_diff - 1
        else:
            age = years_diff
    else:
        age = years_diff
    age_string = str(age) + " years"

if age == 1:
    age_string = age_string.replace("years", "year").replace("months", "month").replace("days", "day")

return age_string

以上代码中使用的一些额外函数是:

def get_todays_date():
    """
    This function returns todays date in proper date object format
    """
    return datetime.now()

And

def get_date_format(str_date):
"""
This function converts string into date type object
"""
str_date = str_date.split("T")[0]
return datetime.strptime(str_date, "%Y-%m-%d")

现在，我们必须为get_date_format()提供像2000-02-29T00:00:00这样的字符串

它将把它转换为日期类型对象，该对象将被提供给get_person_age(date_birth, date_today)。

函数get_person_age(date_birth, date_today)将返回字符串格式的年龄。

from datetime import date

def age(birth_date):
    today = date.today()
    y = today.year - birth_date.year
    if today.month < birth_date.month or today.month == birth_date.month and today.day < birth_date.day:
        y -= 1
    return y

在这种情况下，最经典的问题是如何对待2月29日出生的人。例如:你必须年满18岁才能投票、开车、买酒等等。如果你出生在2004-02-29，你被允许做这些事情的第一天是哪一天:2022-02-28，或2022-03-01?AFAICT，大多数是前者，但一些扫兴的人可能会说是后者。

下面的代码迎合了那一天出生的0.068%(大约)人口:

def age_in_years(from_date, to_date, leap_day_anniversary_Feb28=True):
    age = to_date.year - from_date.year
    try:
        anniversary = from_date.replace(year=to_date.year)
    except ValueError:
        assert from_date.day == 29 and from_date.month == 2
        if leap_day_anniversary_Feb28:
            anniversary = datetime.date(to_date.year, 2, 28)
        else:
            anniversary = datetime.date(to_date.year, 3, 1)
    if to_date < anniversary:
        age -= 1
    return age

if __name__ == "__main__":
    import datetime

    tests = """

    2004  2 28 2010  2 27  5 1
    2004  2 28 2010  2 28  6 1
    2004  2 28 2010  3  1  6 1

    2004  2 29 2010  2 27  5 1
    2004  2 29 2010  2 28  6 1
    2004  2 29 2010  3  1  6 1

    2004  2 29 2012  2 27  7 1
    2004  2 29 2012  2 28  7 1
    2004  2 29 2012  2 29  8 1
    2004  2 29 2012  3  1  8 1

    2004  2 28 2010  2 27  5 0
    2004  2 28 2010  2 28  6 0
    2004  2 28 2010  3  1  6 0

    2004  2 29 2010  2 27  5 0
    2004  2 29 2010  2 28  5 0
    2004  2 29 2010  3  1  6 0

    2004  2 29 2012  2 27  7 0
    2004  2 29 2012  2 28  7 0
    2004  2 29 2012  2 29  8 0
    2004  2 29 2012  3  1  8 0

    """

    for line in tests.splitlines():
        nums = [int(x) for x in line.split()]
        if not nums:
            print
            continue
        datea = datetime.date(*nums[0:3])
        dateb = datetime.date(*nums[3:6])
        expected, anniv = nums[6:8]
        age = age_in_years(datea, dateb, anniv)
        print datea, dateb, anniv, age, expected, age == expected

输出如下:

2004-02-28 2010-02-27 1 5 5 True
2004-02-28 2010-02-28 1 6 6 True
2004-02-28 2010-03-01 1 6 6 True

2004-02-29 2010-02-27 1 5 5 True
2004-02-29 2010-02-28 1 6 6 True
2004-02-29 2010-03-01 1 6 6 True

2004-02-29 2012-02-27 1 7 7 True
2004-02-29 2012-02-28 1 7 7 True
2004-02-29 2012-02-29 1 8 8 True
2004-02-29 2012-03-01 1 8 8 True

2004-02-28 2010-02-27 0 5 5 True
2004-02-28 2010-02-28 0 6 6 True
2004-02-28 2010-03-01 0 6 6 True

2004-02-29 2010-02-27 0 5 5 True
2004-02-29 2010-02-28 0 5 5 True
2004-02-29 2010-03-01 0 6 6 True

2004-02-29 2012-02-27 0 7 7 True
2004-02-29 2012-02-28 0 7 7 True
2004-02-29 2012-02-29 0 8 8 True
2004-02-29 2012-03-01 0 8 8 True