Changing string format (python)

Question

I want to change the string 'datetime.datetime(2018, 4, 15, 12, 59)' into the format '2018-04-15T12:59'.

I created a function that looks like:

def changeDateFormat(date):
    newDate = []
    for i in date.split('datetime')[2].split(','):
        newDate.append(re.sub('[() ]', '', i))
    newStr = newDate[0] + '-0' + newDate[1] + '-' + newDate[2] + 'T' + newDate[3] + ':' + newDate[4]
    return newStr

And it works.

However, I also want it to handle the case where if each unit is less than 10, I want to add a '0'. Right now it just adds a '0' regardless.

I can do it in a very inefficient way, but I wonder how I can do it in a smart way.

Answer 1

I don't understand why you use the string representation of a datetime object but eval is your friend:

>>> import datetime
>>> eval('datetime.datetime(2018, 4, 15, 12, 59)').isoformat()
'2018-04-15T12:59:00'

eval documentation: https://docs.python.org/3/library/functions.html#eval

Answer 2

I assume that you're trying to avoid using the datetime object, because it seems obviously confusing otherwise.

I can do it in a very inefficient way

You are actually not very far away, just one line.

def changeDateFormat(date):
    newDate = []
    for i in date.split('datetime')[2].split(','):
        newDate.append(re.sub('[() ]', '', i))

    pad = '-0' if newDate[1] < 10 else '-'
    newStr = newDate[0] + pad + newDate[1] + '-' + newDate[2] + 'T' + newDate[3] + ':' + newDate[4]
    return newStr

I'm afraid there isn't any smarter way if you're not using the datetime object.

Answer 3

datetime.strftime and eval would be perfect here.

import datetime
# use eval to execute the string like a a command
dt = eval('datetime.datetime(2018, 4, 15, 12, 59)')

formatted_date = dt.strftime('%Y-%m-%dT%H:%M')

output: '2018-04-15T12:59'

Reference: strftime() and strptime() Behavior