How to set different levels for different python log handlers

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");