Python module level logging configuration via code issue

Question

I am trying to get module level logging via code working for three outputs: file, console and application internal(QTextEdit).

I can get all three loggers working with the code below but the application internal logger is not logging all events and the console logger (only) prints each line twice.

I have tried using

logging.getLogger(__name__)

for the file logger instead of root (no logs generated), same for the console (works fine with only 1 line per log output) and same for the MyLogHandler (no logs generated) and tried various combinations of root logger and 'name' logger but can't get all logs working and console only printing one line per log event.

def configCodeRootExample_(self):
    logFileName = self.getLogLocation()
    rootLogger = logging.getLogger('')
    #This logger works
    fileLogger = logging.FileHandler(logFileName)
    fileLogger.setLevel(logging.INFO)
    fileFormatter = logging.Formatter('%(name)-12s: %(levelname)-8s %(message)s')
    fileLogger.setFormatter(fileFormatter)
    rootLogger.addHandler(fileLogger)
    #This logger works but prints output twice
    consoleFormatter = logging.Formatter('%(asctime)s - %(levelname)s - %(name)s - %(module)s - %(funcName)s - %(lineno)d - %(message)s')
    console = logging.StreamHandler()
    console.setLevel(logging.DEBUG)
    console.setFormatter(consoleFormatter)
    rootLogger.addHandler(console)
    #This logger works but only logs a subset of DEBUG events and no INFO events
    myLogHandler = GSLLogHandler()
    myLogHandler.setLevel(logging.DEBUG)
    myLogHandler.setFormatter(fileFormatter)
    rootLogger.addHandler(myLogHandler)

also for the record here is the log handler to output to a listening QTextEdit:

import logging
from loggerpackage.logsignals import LogSignals

class MyLogHandler(logging.Handler): 
    def __init__(self):
        logging.Handler.__init__(self)
        self.logSignals = LogSignals()

    def emit(self, logMsg):
        logMsg = self.format(logMsg)
        self.logSignals.logEventTriggered.emit(logMsg)

If I change the console logger to the module level:

    logger = logging.getLogger(__name__)
    consoleFormatter = logging.Formatter('%(asctime)s - %(levelname)s - %(name)s - %(module)s - %(funcName)s - %(lineno)d - %(message)s')
    console = logging.StreamHandler()
    console.setLevel(logging.DEBUG)
    console.setFormatter(consoleFormatter)
    logger.addHandler(console)

Then only one line is printed for each log event but the formatting is incorrect, it seems to be some sort of default formatter

Don Smythe Don Smythe · Accepted Answer · 2015-12-20T04:05:57

See here for a solution to the duplicate console logging: How to I disable and re-enable console logging in Python?

logger = logging.getLogger()
lhStdout = logger.handlers[0]

... add log handlers

logger.removeHandler(lhStdout)

The issue I was having with the MyLogHandler was that the slot on the QTextEdit wasn't connected in time to receive the first few DEBUG and INFO events.

Python module level logging configuration via code issue

1 Answers