python logging ensure a handler is added only once

Question

I have a piece of code that is initializing a logger as below.

logger = logging.getLogger()
hdlr = logging.FileHandler(\'logfile.log\')
formatter = logging.         


        

Answer 1

Well the logger.addHandler() will not add a handler if the handler already exists. To check if the handler is already there you can check the logger.handlers list:

logger = logging.getLogger()
hdlr = logging.FileHandler('logfile.log')
formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
hdlr.setFormatter(formatter)
logger.addHandler(hdlr) 
logger.setLevel(logging.DEBUG)
print logger.handlers
# []
logger.addHandler(hdlr)
print logger.handlers
# []

Beside that I will suggest putting this code in your main() function if you have one or in the __init__.py file of your package so to not have to call it each time. I will also suggest that you use a named logger, and do not use the root logger. Something like this:

logger = logging.getLogger(__name__)
...

Hope this was helpful :)