How to set different levels for different python l

Question

I've read a few posts on this but I'm still confused. I have this logging setup:

import logging

class MongoHandler(logging.Handler):
    def __init__(self):
        logging.Handler.__init__(self)
        from pymongo import Connection
        self.db = Connection('db_server').db_name

    def emit(self, record):
        try:
            self.db.Logging.save(record.__dict__)
        except:
            print 'Logging Error:  Unable to save log entry to db'

mh = MongoHandler()
sh = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s - %(threadName)s - %(levelname)s - %(message)s')
sh.setFormatter(formatter)
log = logging.getLogger('DeviceMonitor_%s' % hostname)
log.addHandler(mh)
log.addHandler(sh)
log.setLevel(logging.INFO)

I want to be able to set a different level for the StreamHandler and the MongoHandler. Is that possible or do I need to have a second Logger obj?

Answer 1

You can set a different logging level for each logging handler but it seems you will have to set the logger's level to the "lowest". In the example below I set the logger to DEBUG, the stream handler to INFO and the TimedRotatingFileHandler to DEBUG. So the file has DEBUG entries and the stream outputs only INFO. You can't direct only DEBUG to one and only INFO to another handler. For that you'll need another logger.

logger = logging.getLogger("mylog")
formatter = logging.Formatter('%(asctime)s | %(name)s |  %(levelname)s: %(message)s')
logger.setLevel(logging.DEBUG)

stream_handler = logging.StreamHandler()
stream_handler.setLevel(logging.INFO)
stream_handler.setFormatter(formatter)

logFilePath = "my.log"
file_handler = logging.handlers.TimedRotatingFileHandler(filename = logFilePath, when = 'midnight', backupCount = 30)
file_handler.setFormatter(formatter)
file_handler.setLevel(logging.DEBUG)

logger.addHandler(file_handler)
logger.addHandler(stream_handler)

logger.info("Started");
try:
    x = 14
    y = 0
    z = x / y
except Exception as ex:
    logger.error("Operation failed.")
    logger.debug("Encountered {0} when trying to perform calculation.".format(ex))

logger.info("Ended");

Answer 2

I needed a time to understand the point

1. Set the general logger below your subloggers (handlers) (your result of logging.getLogger())
2. Set your subloggers levels on an equal or superior level to your general logger

Answer 3

An addition to GrantVS's answer:

I had to use

logging.basicConfig(level=logging.DEBUG)

in order for it to work. Otherwise great answer, thanks!

Mario

PS: For some reason the system doesn't let me comment GrantVS's answer directly.