python after logging.debug() how to view its logrecord

Question

Recently I came across logging in python.

I have the following code in test.py file

import logging

logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)
logger.addHandler(logging.StreamHandler())
logger.debug("test Message")

Now, is there any way I can print the resulting Logrecord object generated by logger.debug("test Message") because it's stated in the documentation that

LogRecord instances are created automatically by the Logger every time something is logged

https://docs.python.org/3/library/logging.html#logrecord-objects

I checked saving debug into a variable and print it

test = logger.debug("test Message")
print(test)

the output is NONE

My goal is to check/view the final Logrecord object generated by logging.debug(test.py) in the same test.py by using print() This is for my own understanding.

print(LogrecordObject.__dict__)

So how to get hold of the Logrecord object generated by logger.debug("test Message")

Answer 1

A quick way if you just wish to view the LogRecord attributes, you can specify a subset of them as string replacements in a giant string like below.

import logging

view_all_logrecord_attributes = """
asctime - %(asctime)s
created - %(created)f

filename - %(filename)s
funcName - %(funcName)s
levelname - %(levelname)s
levelno - %(levelno)s
lineno - %(lineno)d
message - %(message)s
module - %(module)s
msecs - %(msecs)d

name - %(name)s
pathname - %(pathname)s
process - %(process)d
processName - %(processName)s
relativeCreated - %(relativeCreated)d

thread - %(thread)d
threadName - %(threadName)s
"""

logging.basicConfig(format= view_all_logrecord_attributes, level=logging.DEBUG)
logging.debug('Message text here')

The list is from the documentation: https://docs.python.org/3/library/logging.html#logrecord-attributes

And an example output would be:

asctime - 2024-02-21 08:42:10,428
created - 1708465330.428894

filename - <stdin>
funcName - <module>
levelname - DEBUG
levelno - 10
lineno - 1
message - Message text here
module - <stdin>
msecs - 428

name - root
pathname - <stdin>
process - 94365
processName - MainProcess
relativeCreated - 749

thread - 8042958848
threadName - MainThread

Answer 2

There is no return in debug()

# Here is the snippet for the source code
    def debug(self, msg, *args, **kwargs):
        if self.isEnabledFor(DEBUG):
            self._log(DEBUG, msg, args, **kwargs)

If you wanna get LogRecord return, you need to redefine a debug(), you can overwrite like this:

import logging

DEBUG_LEVELV_NUM = 9 
logging.addLevelName(DEBUG_LEVELV_NUM, "MY_DEBUG")

def _log(self, level, msg, args, exc_info=None, extra=None, stack_info=False):
    sinfo = None
    fn, lno, func = "(unknown file)", 0, "(unknown function)"
    if exc_info:
        if isinstance(exc_info, BaseException):
            exc_info = (type(exc_info), exc_info, exc_info.__traceback__)
        elif not isinstance(exc_info, tuple):
            exc_info = sys.exc_info()
    record = self.makeRecord(self.name, level, fn, lno, msg, args,
                             exc_info, func, extra, sinfo)
    self.handle(record)
    return record


def my_debug(self, message, *args, **kws):
    if self.isEnabledFor(DEBUG_LEVELV_NUM):
        # Yes, logger takes its '*args' as 'args'.
        record = self._log(DEBUG_LEVELV_NUM, message, args, **kws)
        return record

logger = logging.getLogger(__name__)
logging.Logger.my_debug = my_debug
logging.Logger._log = _log
logger.setLevel(DEBUG_LEVELV_NUM)
logger.addHandler(logging.StreamHandler())
test = logger.my_debug('test custom debug')
print(test)

Reference: How to add a custom loglevel to Python's logging facility