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scy

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scy
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Python: *has very flexible logging system*

also Python: *has no format string placeholder for fractional seconds*

me, wanting a ISO 8601 compatible timestamp with milliseconds in his logs:

[Edit: fixed and improved version in the replies]

#Python #logging #ISO8601

A Python class ISOTimeFormatter (extending logging.Formatter) that uses an f-string to inject record.msecs into the format string passed to time.strftime. Code follows:

class ISOTimeFormatter(logging.Formatter):
@staticmethod
def formatTime(
record: logging.LogRecord, datefmt: str | None = None
) -> str:
return time.strftime(f"%Y-%m-%d %H:%M:%S.{record.msecs:03.0f}%z")

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scy

Als Antwort auf scy • 1 Tag her • •

Also, this was painful to read.

docs.python.org/3/library/logg…

#Python #logging

Changed in version 3.3: Previously, the default format was hard-coded as in this example: 2010-09-06 22:38:15,292 where the part before the comma is handled by a strptime format string ('%Y-%m-%d %H:%M:%S'), and the part after the comma is a millisecond value. Because strptime does not have a format placeholder for milliseconds, the millisecond value is appended using another format string, '%s,%03d' — and both of these format strings have been hardcoded into this method. With the change, these strings are defined as class-level attributes which can be overridden at the instance level when desired. The names of the attributes are default_time_format (for the strptime format string) and default_msec_format (for appending the millisecond value).

Changed in version 3.9: The default_msec_format can be None.

logging — Logging facility for Python

Source code: Lib/logging/__init__.py Important: This page contains the API reference information. For tutorial information and discussion of more advanced topics, see Basic Tutorial, Advanced Tutor...

^{Python documentation}

#Python #logging

Als Antwort auf scy

Daniel Bohrer

Als Antwort auf scy • 1 Tag her • •

ouch… I guess changing the stdlib to introduce a new millisecond value for strptime is a no-go

Als Antwort auf Daniel Bohrer

scy

Als Antwort auf Daniel Bohrer • 1 Tag her • •

I don't really understand why they're not doing it (didn't take the time to read up on it either though), but yeah.

Note however that strptime has %f, but strftime doesn't:

docs.python.org/3/library/time…

And all of these just apply to the `time` module, not to `datetime`, which has a different implementation of strftime that _also_ supports %f.

docs.python.org/3/library/date…

Which means that I'll use datetime instead and be okay:

chaos.social/@scy/114359324930…

time — Time access and conversions

This module provides various time-related functions. For related functionality, see also the datetime and calendar modules. Although this module is always available, not all functions are available...

^{Python documentation}

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Fink

Als Antwort auf scy • 1 Tag her • •

RFC 3339 ftw
And yes 🫠

ijmacd.github.io/rfc3339-iso86…

RFC 3339 vs ISO 8601

Comparison between RFC 3339 and ISO 8601 date formats

^{ijmacd.github.io}

Als Antwort auf scy

Okay, yeah, so, that method was BS for two reasons: I'm formatting the milliseconds from the log record, but the rest of the timestamp from "now" (lol, ouch) – but also, the underlying problem is using time.strftime (like the base class) instead of the more modern datetime.datetime.strftime. Because the latter actually _does_ have a format string placeholder for microseconds (not milliseconds though).

So, after a bit of iteration, I think I'll be going with this one:

#Python #logging

The class now sets its format string in a class attribute "default_time_format" just like the base class does. It's also using datetime.datetime.fromtimestamp() to convert record.created (a float) into a (naive) datetime object, and then calls .astimezone() without arguments to convert it into an aware datetime for the local timezone. After that, it's just a call to strftime with either the datefmt string passed to the method or the class-level default as its format string.

Code follows:

class ISOTimeFormatter(logging.Formatter):
default_time_format = "%Y-%m-%d %H:%M:%S.%f%z"

def formatTime(
self, record: logging.LogRecord, datefmt: str | None = None
) -> str:
return (
datetime.fromtimestamp(record.created)
.astimezone() # convert to aware object using local timezone
.strftime(datefmt or self.default_time_format)
)

#Python #logging

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Paul McGuire

Als Antwort auf scy • 1 Tag her • •

The only way I've found to format time to milliseconds is to use a `[:23]` slice.

Python code to format a datetime to milliseconds, not microseconds:

>>> fmt = "%Y-%m-%d %H:%M:%S.%f"
>>> s = datetime.now().strftime(fmt)
>>> s
'2025-04-18 09:05:30.985025'
>>> s_ms_only = datetime.now().strftime(fmt)[:23]
>>> s_ms_only
'2025-04-18 09:05:46.473'
>>> print(f"{datetime.now():{fmt}}")
2025-04-18 09:07:12.268476
>>> print(f"{datetime.now():{fmt}}"[:23])
2025-04-18 09:10:07.586

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