how to log all errors in python

Question

I want to save ALL ERRORS into a file which means the errors outside an exception, also get in the log file.

for example import some module and in the begining of a script, set it to save the errors; something like this:

import blob
blob.save_errors(filename)

try:
  lst = ['a']
  print(lst[2]) # save this Error
except:
  pass

print(2/0) # also save this error

Like this - https://stackoverflow.com/questions/1508467/log-exception-with-traceback-in-python — Devang Sanghani, Feb 21 '22 at 05:07
is only save the errors in exception block and should set it manual. — DANIEL1475, Feb 21 '22 at 05:09
[Logging module](https://docs.python.org/3/howto/logging.html) is a good place to start. It's built into standard library. — bfris, Feb 21 '22 at 05:14

Ihor Konovalenko · Answer 1 · 2022-02-21T05:48:37.690

There is no easy automatic way to process all the exception, it contradict with exception handling idea.

One of solutions: we can log all uncatched exceptions like this way:

import sys
import logging

logger = logging.getLogger(__name__)
handler = logging.StreamHandler(stream=sys.stdout)
logger.addHandler(handler)

def handle_exception(exc_type, exc_value, exc_traceback):
    if issubclass(exc_type, KeyboardInterrupt):
        sys.__excepthook__(exc_type, exc_value, exc_traceback)
    else:
        logger.critical("Exception occured:", exc_info=(exc_type, exc_value, exc_traceback))

sys.excepthook = handle_exception

# Just to test
if __name__ == "__main__":
    raise Exception("Something happend!")

And to log all handled exception we need to all logging in except block:

try:
    ...
except:
    logger.error("Exception occured:", exc_info=(exc_type, exc_value, exc_traceback))
    ...

Other way to deal with exception is to handle them in top-level function. All non-handled exceptions from downstream functions will be processed in top-level except block:

def my_main_func():
    try:
        run_my_application_logic()
    except:
        # Logging
        logger.error("Exception occured:", exc_info=(exc_type, exc_value, exc_traceback))

def run_my_application_logic():
    first_step_of_app()
    second_step_of_app()
    third_step_of_app()


if __name__ == "__main__":
    my_main_func()

well thanks, but the first solution doesn't save worl actually, just prints the error same as before (I want to save the errors in a file) — DANIEL1475, Feb 21 '22 at 09:01
@DANIEL1475 `looger` can write log to file. You just need to properly configure logger. https://stackoverflow.com/questions/6386698/how-to-write-to-a-file-using-the-logging-python-module — Ihor Konovalenko, Feb 21 '22 at 13:43

how to log all errors in python

1 Answers1