Python - Get Yesterday's date as a string in YYYY-MM-DD format

问题

As an input to an API request I need to get yesterday's date as a string in the format YYYY-MM-DD. I have a working version which is:

yesterday = datetime.date.fromordinal(datetime.date.today().toordinal()-1)
report_date = str(yesterday.year) + \
   ('-' if len(str(yesterday.month)) == 2 else '-0') + str(yesterday.month) + \
   ('-' if len(str(yesterday.day)) == 2 else '-0') + str(yesterday.day)

There must be a more elegant way to do this, interested for educational purposes as much as anything else!

回答1:

You Just need to subtract one day from today's date. In Python datetime.timedelta object lets you create specific spans of time as a timedelta object.

datetime.timedelta(1) gives you the duration of "one day" and is subtractable from a datetime object. After you subtracted the objects you can use datetime.strftime in order to convert the result --which is a date object-- to string format based on your format of choice:

>>> from datetime import datetime, timedelta
>>> yesterday = datetime.now() - timedelta(1)

>>> type(yesterday)                                                                                                                                                                                    
>>> datetime.datetime    

>>> datetime.strftime(yesterday, '%Y-%m-%d')
'2015-05-26'

Note that instead of calling the datetime.strftime function, you can also directly use strftime method of datetime objects:

>>> (datetime.now() - timedelta(1)).strftime('%Y-%m-%d')
'2015-05-26'

As a function:

def yesterday(string=False):
    yesterday = datetime.now() - timedelta(1)
    if string:
        return yesterday.strftime('%Y-%m-%d')
    return yesterday

回答2:

An alternative answer that uses today() method to calculate current date and then subtracts one using timedelta(). Rest of the steps remain the same.

https://docs.python.org/3.7/library/datetime.html#timedelta-objects

from datetime import date, timedelta
today = date.today()
yesterday = today - timedelta(days = 1)
print(today)
print(yesterday)

Output: 
2019-06-14
2019-06-13

回答3:

>>> import datetime
>>> datetime.date.fromordinal(datetime.date.today().toordinal()-1).strftime("%F")
'2015-05-26'

回答4:

Calling .isoformat() on a date object will give you YYYY-MM-DD

from datetime import date, timedelta
(date.today() - timedelta(1)).isoformat()

来源：https://stackoverflow.com/questions/30483977/python-get-yesterdays-date-as-a-string-in-yyyy-mm-dd-format

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python

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python-3.x

date

datetime