Converting string 'yyyy-mm-dd' into datetime

I have a raw input from the user such as "2015-01-30"...for the query I am using, the date has to be inputed as a string as such "yyyy-mm-dd".

I would like to increment the date by 1 month at end of my loop s.t "2015-01-30" becomes "2015-02-27" (ideally the last business day of the next month). I was hoping someone could help me; I am using PYTHON, the reason I want to convert to datetime is I found a function to add 1 month.

Ideally my two questions to be answered are (in Python):

1) how to convert string "yyyy-mm-dd" into a python datetime and convert back into string after applying a timedelta function

2) AND/or how to add 1 month to string "yyyy-mm-dd"

Solution

You can use a one-liner, that takes the datetime, adds a month (using a defined function), and converts back to a string:

x = add_months(datetime.datetime(*[int(item) for item in x.split('-')]), 1).strftime("%Y-%m-%d")

>>> import datetime, calendar
>>> x = "2015-01-30"
>>> x = add_months(datetime.datetime(*[int(item) for item in x.split('-')]), 1).strftime("%Y-%m-%d")
>>> x
'2015-02-28'
>>>

add_months:

def add_months(sourcedate,months):
    month = sourcedate.month - 1 + months
    year = sourcedate.year + month / 12
    month = month % 12 + 1
    day = min(sourcedate.day,calendar.monthrange(year,month)[1])
    return datetime.date(year,month,day)