Python regex to parse the datetime.datetime object from string

Question

I have the following string:

"{'foo': datetime.datetime(2022, 5, 23, 0, 0, tzinfo=tzlocal()), 'bar': 'some data', 'foobar': datetime.datetime(2022, 8, 3, 13, 57, 41, tzinfo=<UTC>), 'barlist': ['hello', 'world']}"

I want to be able to match all the datetime.datetime(...) strings within this string and replace it with the numbers in a list form only. So this is the expected result:

"{'foo': [2022, 5, 23, 0, 0], 'bar': 'some data', 'foobar': [2022, 8, 3, 13, 57, 41], 'barlist': ['hello', 'world']}"

I have something like this:

DATETIME_PATTERN = r"datetime.datetime\(((\d+)(,\s*\d+)*), tzinfo=.*\)"
modified_input_str = re.sub(DATETIME_PATTERN, r"[\1]", input_str)

but it replaces a big chunk of data inbetween the matches. How can I modify the regex to accomplish what I want?

Conclusion: I made a modification of the current best answer so it fits my particular usecase more:

DATETIME_PATTERN = r"datetime\.datetime\((\d+(?:,\s*\d+)*), tzinfo=(?:[^\s\d])*\)"

# The difference is that the string at the end of 'tzinfo=' can be anything but whitespace or numbers.

Please add the required language tag. Not all regex engines are created equal. — WJS
– WJS, Commented Jan 31, 2023 at 15:54
@WiktorStribiżew oops sorry I accidentally added indents to the mock data which worked for this pattern. Just removed the newlines so it reflects more closely with the data I'm working with! — avhhh
– avhhh, Commented Jan 31, 2023 at 17:11
What about datetime\.datetime\(((\d+)(,\s*\d+)*), tzinfo=(?:\(\)|[^()])*\)? Do you expect anything inside the parentheses? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jan 31, 2023 at 17:15

Wiktor Stribiżew · Accepted Answer · 2023-01-31 18:43:54Z

1

You can use

datetime\.datetime\((\d+(?:,\s*\d+)*), tzinfo=(?:\(\)|[^()])*\)

Details:

datetime\.datetime\( - a datetime.datetime( string
(\d+(?:,\s*\d+)*) - Group 1: one or more digits and then zero or more repetitions of a comma + zero or more whitespaces and then one or more digits
, tzinfo= - a literal string
(?:\(\)|[^()])* - zero or more repetitions of a () string or any char other than ( and )
\) - a ) char.

See the regex demo.

answered Jan 31, 2023 at 18:43

Wiktor Stribiżew

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