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I know there are a lot of answers to this question online, but none of them have worked for me. I am trying to convert a date string into a Datetime object, of the following format: yyyy-mm-dd

My date_string is '2017-02-02T00:00:00Z'

I am trying to convert it by doing date_value = datetime.datetime.strptime(date_string, '%Y%m%d') but I'm getting the following error:

ValueError: time data '"2017-02-02T00:00:00Z"' does not match format '%Y%m%d'

Also, should I be worried about the double quotes around my date_string string?

Adam
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  • Does this answer your question? [How do I parse an ISO 8601-formatted date?](https://stackoverflow.com/questions/127803/how-do-i-parse-an-iso-8601-formatted-date) -> esp. https://stackoverflow.com/a/62769371/10197418 ;-) – FObersteiner Jun 02 '21 at 12:43
  • Your date/time string pattern is incorrect. It doesn't account for the time component at all. – vintastic Jun 02 '21 at 12:43
  • @MrFuppes Thank you for the link. I have tried the suggestion `date = datetime.fromisoformat("2017-02-02T00:00:00.Z")` but I get an error `ValueError: Invalid isoformat string: '"2017-02-02T00:00:00.Z"'` – Adam Jun 02 '21 at 13:13
  • Did you check out the second link in my comment? – FObersteiner Jun 02 '21 at 14:21

2 Answers2

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The second argument in the method strptime is the pattern of your string.

Here is the full list of available code formats. https://docs.python.org/3/library/datetime.html#strftime-and-strptime-format-codes

All the remaining "non-informative" characters in your string can simply be put as-is in there correct places.

Thanks to @MrFuppes for this info: you should also parse the trailing "Z" as %z. This will signal python that it's a UTC datetime and not a local datetime.

Your code should be :

date_string = '2017-02-02T00:00:00Z'
date_value = datetime.datetime.strptime(date_string, '%Y-%m-%dT%H:%M:%S%z')

As for the extra quotes, that's not wanted. You should try this beforehand :

date_string = date_string.strip("'").strip('"')

If strip() didn't work, you can call eval instead (usually not recommended) :

date_string = eval(date_string)
Whole Brain
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    `Z` should not be parsed with a literal "Z" in the parsing directive. Why? This results in naive datetime, which Python treats as *local time*, while Z signals UTC. And secondly, using `eval` for something that can be done with a simple `replace` is inappropriate. – FObersteiner Jun 02 '21 at 12:56
  • Thanks a lot for the informative Z. Although `replace` is less appropriate than `strip` IMO, I agree with you about `eval`. – Whole Brain Jun 02 '21 at 13:17
  • Thank you for helping. I've tried the same sequence as you but I'm still getting a similar error (even after stripping the quotes): `ValueError: time data '"2017-02-02T00:00:00Z"' does not match format '%Y-%m-%dT%H:%M:%S%z'` – Adam Jun 02 '21 at 13:19
  • That's because the character (quote or doublequote) you're trying to remove should be the inner one shown in the Exception. So it would be `.strip('"')`. You can actually chain the `strip` method to handle both cases. I have updated my answer. – Whole Brain Jun 02 '21 at 13:24
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    Thank you! There was another slight issue with regards to comparing "offset-naive" and "offset-aware" which threw an error, but otherwise this works! Thank you. – Adam Jun 02 '21 at 13:38
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The solution is to parse your date_string first, and that should help. Using strptime() right away on an unparsed datetime string can sometimes cause problems. Also you shouldn't worry about your double quotes, it's fine.

First, install the python-dateutil library if you haven't already (pip install python-dateutil at the command line). Then test the solution with the following code.

import datetime
import dateutil.parser

date_string = '2017-02-02T00:00:00Z'

#we parse the string, it becomes a datetime object
parsed_date_string = dateutil.parser.parse(date_string)
print(parsed_date_string)

#output looks like this: 2017-02-02 00:00:00+00:00

#now your statement will work
date_value = datetime.datetime.strptime(str(parsed_date_string), '%Y-%m-%d %H:%M:%S%z')
print(date_value)

#output will also be: 2017-02-02 00:00:00+00:00

The strptime() statement worked this time because we parsed our date first with parse(). Note also that to use strptime() we need to cast our parsed_date_string back to a string because parse() converts our original string to an object of class datetime.datetime and strptime() is expecting a string.

Hopefully that helped.

Khaleel OBrien
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