Python 3 Convert ISO 8601 to milliseconds

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I'm receiving an ISO 8601 format from an API GET request ("2020-02-25T00:02:43.000Z"). I'm trying to convert it to milliseconds, because that format is required in the payload of the API POST call. I've been successful running the code from a Linux system, but I get ValueError: Invalid format string from Windows.

From Linux:

import dateutil.parser

time = "2020-02-25T00:02:43.000Z"
parsed_time = dateutil.parser.parse(time)
t_in_millisec = parsed_time.strftime('%s%f')
t_in_millisec[:-3]

returns

'1582588963000'

From Windows:

import dateutil.parser

      1 time = "2020-02-25T00:02:43.000Z"
      2 parsed_time = dateutil.parser.parse(time)
----> 3 t_in_millisec = parsed_time.strftime('%s%f')

ValueError: Invalid format string

Is there a way around this?

python-dateutil python-3.x
2 Answers

Here is the list of what works on windows and indeed the %s is not present. https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/strftime-wcsftime-strftime-l-wcsftime-l?redirectedfrom=MSDN&view=vs-2019

I always use datetime, if you have the opportunity to use it here is an example :

datetime.datetime(2020,2,25,0,2,43).timestamp()

or 

import datetime
time = "2020-02-25T00:02:43.000Z"
date = datetime.datetime.strptime(time, '%Y-%m-%dT%H:%M:%S.%fZ')
timestamp = str((date - datetime.datetime(1970, 1, 1)).total_seconds()*1000)
print(timestamp[:-2])
user_110634790

The reason this doesn't work in Windows is that the strftime function calls the native OS's C library, and Unix ticks (i.e. seconds since midnight on Jan 1, 1970) aren't a part of the Windows operating system.

If you want to get the number of seconds since Jan 1, 1970, then you can simply subtract the original date and get the total seconds from the timedelta. Python makes this easier and provides a timestamp function that does the computation for you (and includes subseconds as a decimal component).

import dateutil.parser

time = "2020-02-25T00:02:43.000Z"
parsed_time = dateutil.parser.parse(time)
timestamp = parsed_time.timestamp() * 1000
return str(int(timestamp))
user_14934220
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