logging exception into log file in python

Question

I have to create a one single log file for entire application and if there is any exception raised by any of module in the application , exception should go into except block and error should be written to log file . This log file should not be overridden instead if there are exceptions raised by multiple modules , all exceptions should be logged into one single log file .

I have tried logger with below code , but it is not creating log file :

import logging
with open("D:\logfile\log.txt", "w") as log:
    logging.basicConfig(filename=log, level=logging.DEBUG, format='%(asctime)s %(levelname)s %(name)s %(message)s')
    logger=logging.getLogger(__name__)
    try:
        1/0
    except ZeroDivisionError as err
        logger.error(err)

also using with clause needs indentation and I do not want to use all modules under one with clause , instead I want to simply create one log file at the beginning of program and as program executes and modules raise an exceptions those exceptions should be written into one log file .

I'm not sure to understand, you don't need to open a file like this to use the logger module. You can get rid of the with part for a start. — fpietka
– fpietka, Commented Aug 20, 2020 at 5:39
Can you please clarify what is your question? What is going wrong with the code – is there an error? What behaviour do you expect, and what behaviour do you get? Also take note that passing a file object to the parameter filename should tell you to rereead the logging documentation. — MisterMiyagi
– MisterMiyagi, Commented Aug 20, 2020 at 5:46

samsi · Accepted Answer · 2020-08-20 06:42:45Z

3

I don't know the logging module, but some googling suggests that the logging module supports writing the traceback into the logfile. Also your code didn't seem to work on my machine (Python v3.8.5), so i edited it so it works.

logging.exception('text') logs the traceback to the logfile, and you can specify a message which will displayed beforehand.

The code:

import logging

#with open("log.txt", "w") as log:
logging.basicConfig(filename='log.txt', level=logging.DEBUG, format='%(asctime)s %(levelname)s %(name)s %(message)s')
logger=logging.getLogger(__name__)
try:
    1/0
except ZeroDivisionError:
    logging.exception('Oh no! Error. Here is the traceback info:')

The logfile:

2020-08-20 08:31:02,310 ERROR root Oh no! Error. Here is the traceback info:
Traceback (most recent call last):
  File "logger.py", line 7, in <module>
    1/0
ZeroDivisionError: division by zero

This has the advantage that the whole traceback is logged, which usually more helpful.

answered Aug 20, 2020 at 6:42

samsi

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2 Comments

Hefe Over a year ago

Question: why did you comment out the with statement? If we uncomment that and tab over the next two lines, would it overwrite the log file for every exception?

samsi Over a year ago

The code is based off of the code from Jay, I only did some adjustments. I left the line I commented out from Jays code in, so it's a bit clearer. I now realise it just adds to the confusion. Anyways, the commented line is NOT needed, since the logging module takes care of the file handling.

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