Changing format of handler

It appears that you cannot change the format (easily), but have to start a new logger/sink for it (and then stop the previous one), or am I missing something?

I think it would be good to have a method to update the format of a handler (which would take care of handling caches etc) maybe.

Currently I am using:

log_format = loguru._defaults.LOGURU_FORMAT + ' ({extra[reqid]}:{extra[ip]}:{extra[user]})'
logger = loguru.logger
logger.start(sys.stderr, format=log_format)
logger = logger.bind(reqid='-', ip='-', user="-")
logger.stop(0)

And then later bind extra per request:

def get_logger_for_request(request):
    global request_id
    request_id += 1
    ip = request.headers.get("x-real-ip", "?")
    return logger.bind(reqid=request_id, ip=ip, user="?")

Something like logger._handlers[0].set_format(loguru._defaults.LOGURU_FORMAT + ' ({extra[reqid]}:{extra[ip]}:{extra[user]})') could replace the first block here.

I’ve found that there is Handler.update_format, which looked promising, but then it is only about updating formats for color.

Another way would be to use LOGURU_AUTOINIT=0, but I wonder what you think about changing the format on the fly.

[Delgan]

@jcmcken The underlying datetime object is indeed timezone aware.

Moreover, when using "{time}" in your format, the timezone offset will be part of the formatted datetime.

logger.remove()
logger.add(sys.stderr, format="{time} - {message}")
logger.info("Test")
# => '2018-12-15T09:06:12.354664+0100 - Test'

You don’t see that in the demonstration gif because I chosen to not use ISO8601 for the default logger format in order to reduce verbosity. The default logger format is more like format="{time:YYYY-MM-DD HH:mm:ss.SSS} {message}", it’s just the local time naively displayed.

There are two things to distinguish: the default time format and the default logger format.

If you want to display timezone by default, you can set the LOGURU_FORMAT environment variable to the format you would prefer, like for example "<g>{time}</g> {level} <lvl>{message}</lvl>". See also the tokens available for datetime formatting.

[blueyed]

@Delgan Thanks for your help, I am the following in a log module, where I import logger from across the app:

import sys

import loguru

# log_format = '<green>{time:YYYY-MM-DD HH:mm:ss.SSS}</green> | <level>{level: <8}</level> | <cyan>{name}</cyan>:<cyan>{function}</cyan>:<cyan>{line}</cyan> - <level>{message}</level> ({extra})'
log_format = loguru._defaults.LOGURU_FORMAT + ' ({extra[reqid]}:{extra[ip]}:{extra[user]})'

logger = loguru.logger

logger.configure(
    handlers=[
        {"sink": sys.stderr, "format": log_format},
    ],
    extra={"reqid": "-", "ip": "-", "user": "-"},
)