colorlog.LevelFormatter does not allow to use dict for fmt parameter on python 3.8

[PanovEduard]

Traceback (most recent call last):
File "D:/gitrep/DevOpsCI/DiasoftBuild/DiasoftBuild.py", line 36, in
from LogInit import file_formatter
File "D:\gitrep\DevOpsCI\DiasoftBuild\CommonLib\LogInit.py", line 98, in
formatter = LevelFormatter(
File "C:\Users\panov-ea\AppData\Roaming\Python\Python38\site-packages\colorlog\colorlog.py", line 160, in init
super(LevelFormatter, self).init(
File "C:\Users\panov-ea\AppData\Roaming\Python\Python38\site-packages\colorlog\colorlog.py", line 91, in init
super(ColoredFormatter, self).init(fmt, datefmt, style)
File "C:\Users\panov-ea\AppData\Local\Programs\Python\Python38-32\lib\logging_init_.py", line 576, in init
self.style.validate()
File "C:\Users\panov-ea\AppData\Local\Programs\Python\Python38-32\lib\logging_init.py", line 456, in validate
for _, fieldname, spec, conversion in _str_formatter.parse(self._fmt):
File "C:\Users\panov-ea\AppData\Local\Programs\Python\Python38-32\lib\string.py", line 261, in parse
return _string.formatter_parser(format_string)
TypeError: expected str, got dict

[Northbadge]

Seems like Python-logging was updated in 3.8 with validation checks.
python/cpython#9703

Adding a validate=false flag into the logging.formatter initializer for Python >= 3.8 should fix it

In my case, I just commented out the validate call in my logging lib.

[borntyping]

Could you provide a minimal code example you would expect to work? I'm very unclear on what usage would require passing a dictionary instead of a string as the fmt parameter.

[Northbadge]

Could you provide a minimal code example you would expect to work? I'm very unclear on what usage would require passing a dictionary instead of a string as the fmt parameter.

The LevelFormatter class seems to have specifically built in support for dicts as the fmt parameter

python-colorlog/colorlog/colorlog.py

Lines 133 to 159 in 809e896

	class LevelFormatter(ColoredFormatter):
	"""An extension of ColoredFormatter that uses per-level format strings."""
	def __init__(self, fmt=None, datefmt=None, style='%',
	log_colors=None, reset=True,
	secondary_log_colors=None):
	"""
	Set the per-loglevel format that will be used.
	Supports fmt as a dict. All other args are passed on to the
	``colorlog.ColoredFormatter`` constructor.
	:Parameters:
	- fmt (dict):
	A mapping of log levels (represented as strings, e.g. 'WARNING') to
	different formatters. (*New in version 2.7.0)
	(All other parameters are the same as in colorlog.ColoredFormatter)
	Example:
	formatter = colorlog.LevelFormatter(fmt={
	'DEBUG':'%(log_color)s%(msg)s (%(module)s:%(lineno)d)',
	'INFO': '%(log_color)s%(msg)s',
	'WARNING': '%(log_color)sWARN: %(msg)s (%(module)s:%(lineno)d)',
	'ERROR': '%(log_color)sERROR: %(msg)s (%(module)s:%(lineno)d)',
	'CRITICAL': '%(log_color)sCRIT: %(msg)s (%(module)s:%(lineno)d)',
	})

There's an example there. Perhaps it could be reworked to not store the dict into fmt, but that would seem like it's just a complicated way of bypassing the validation check.

[borntyping]

My mistake, it's a long time since I've looked at the code for LevelFormatter and the original issue wasn't very clear.

[borntyping]

Fix released as version 4.1.0: https://pypi.org/project/colorlog/4.1.0/