Python logger: won't overwrite the original log?

Question

So, when I copy paste the following x times to the python prompt, it add the log x times to the end of the designated file.

How can I change the code so that each ti

Answer 1

If I understand correctly, you're running a certain Python process for days at a time, and want to rotate the log every day. I'd recommend you go a different route, using a handler that automatically rotates the log file, e.g. http://www.blog.pythonlibrary.org/2014/02/11/python-how-to-create-rotating-logs/

But, if you want to control the log using the process in the same method you're comfortable with (Python console, pasting in code.. extremely unpretty and error prone, but sometimes quick-n-dirty is sufficient for the task at hand), well...

Your issue is that you create a new FileHandler each time you paste in the code, and you add it to the Logger object. You end up with a logger that has X FileHandlers attached to it, all of them writing to the same file. Try this:

import logging
paths = {'work': ''}
logger = logging.getLogger('oneDayFileLoader')
if logger.handlers:
   logger.handlers[0].close()
   logger.handlers = []
logHandler = logging.FileHandler(os.path.join(paths["work"] , "oneDayFileLoader.log"), mode='w')
formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
logHandler.setFormatter(formatter)
logger.addHandler(logHandler) 
logger.setLevel(logging.DEBUG)
logger.error('overwrite')

Based on your request, I've also added an example using TimedRotatingFileHandler. Note I haven't tested it locally, so if you have issues ping back.

import logging
from logging.handlers import TimedRotatingFileHandler

logPath = os.path.join('', "fileLoaderLog")
logger = logging.getLogger('oneDayFileLoader')
logHandler = TimedRotatingFileHandler(logPath,
                                   when="midnight",
                                   interval=1)
formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
logHandler.setFormatter(formatter)
logger.addHandler(logHandler) 
logger.setLevel(logging.DEBUG)
logger.error('overwrite')