b26c897a8b
* [ISSUE #25646] support parsing of non utc dates * [ISSUE #25646] improve parsing * [ISSUE #25646] removing timezone for DatetimeParser interface * [ISSUE #25646] fix tests
45 lines
1.9 KiB
Python
45 lines
1.9 KiB
Python
#
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# Copyright (c) 2023 Airbyte, Inc., all rights reserved.
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#
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import datetime
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from typing import Union
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class DatetimeParser:
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"""
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Parses and formats datetime objects according to a specified format.
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This class mainly acts as a wrapper to properly handling timestamp formatting through the "%s" directive.
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%s is part of the list of format codes required by the 1989 C standard, but it is unreliable because it always return a datetime in the system's timezone.
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Instead of using the directive directly, we can use datetime.fromtimestamp and dt.timestamp()
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"""
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def parse(self, date: Union[str, int], format: str):
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# "%s" is a valid (but unreliable) directive for formatting, but not for parsing
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# It is defined as
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# The number of seconds since the Epoch, 1970-01-01 00:00:00+0000 (UTC). https://man7.org/linux/man-pages/man3/strptime.3.html
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#
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# The recommended way to parse a date from its timestamp representation is to use datetime.fromtimestamp
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# See https://stackoverflow.com/a/4974930
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if format == "%s":
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return datetime.datetime.fromtimestamp(int(date), tz=datetime.timezone.utc)
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parsed_datetime = datetime.datetime.strptime(str(date), format)
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if self._is_naive(parsed_datetime):
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return parsed_datetime.replace(tzinfo=datetime.timezone.utc)
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return parsed_datetime
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def format(self, dt: datetime.datetime, format: str) -> str:
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# strftime("%s") is unreliable because it ignores the time zone information and assumes the time zone of the system it's running on
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# It's safer to use the timestamp() method than the %s directive
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# See https://stackoverflow.com/a/4974930
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if format == "%s":
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return str(int(dt.timestamp()))
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else:
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return dt.strftime(format)
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def _is_naive(self, dt: datetime.datetime) -> bool:
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return dt.tzinfo is None or dt.tzinfo.utcoffset(dt) is None
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