sword wrote:
On Nov 16, 7:40 pm, Jean-Michel Pichavant <jeanmic...@sequans.com>
wrote:
sword wrote:
The logging cookbook gives an Filter example, explainning how to add
contextural info to log. I can't figure out how to filter log from it.
Suppose I have 3 file, a.py, b.py and main.py
#file: a.py
import logging
logger=logging.getLogger(__name__)
def print_log():
logger.debug("I'm module a")
#file: b.py just like a.py
import logging
logger=logging.getLogger(__name__)
def print_log():
logger.debug("I'm module b")
#file: main.py
import logging
from logging import Filter
logging.basicConfig(level=logging.DEBUG)
logger=logging.getLogger("main")
logger.debug("This is main process")
logger.addFilter(Filter("a"))
And I expected that the console output would contain main and b module
log only. But it turned out that all logs there. Is it the problem of
root logger?
Hi,
First of all, in the code you provided we can't see where you import a &
b, and when you call their respective print_log method.
Secondly,Filter("a") would allow only the "a" log events, not forbid
them. quoting the docs: "if name is specified, it names a logger which,
together with its children, will have its events allowed through the
filter."
As for your problem it may come from the fact that you applied the
filter to the 'main' logger, while you probably want to add the filter
to the *root* logger. Your current hierarchy is
root
- main
- a
- b
events fired from 'a' will be handled by the root logger, not the main.
root = logging.getLogger()
root.addFilter('main')
root.addFilter('a')
root.addFilter('b')
JM
Thanks for your reply. I tried to edit the source a bit, now the
main.py looks like this:
#main.py
import logging
from logging import Filter
import a
import b
logging.basicConfig(level=logging.DEBUG)
root = logging.getLogger()
root.addFilter(Filter("GoneWithTheWind")) #so I suppose no log msg
would pass this filter
logger = logging.getLogger("main")
logger.debug("main process")
a.print_log()
b.print_log()
####
And It still prints out all the log msg. :(
You need to add you filter to the handler(s) of the root logger, not the
root logger itself.
Filters to loggger object are applied only when the log event is raised,
i.e. when one of the logging method error, info, warning, debug is called.
In your case, log events are raised by other loggers than the root
logger, so its filter will not apply.
However any filter applied to the root *handlers* will be applied to any
log processed by the handler, including log event raised by sub-logger.
root.handlers[-1].addFilter(Filter("GoneWithTheWind")) #so I suppose no log msg
JM
Quoting http://docs.python.org/library/logging.html#filter-objects
"Note that filters attached to handlers are consulted whenever an event is emitted
by the handler, whereas filters attached to loggers are consulted whenever an event is
logged to the handler (using debug(), info(), etc.) This means that events which have
been generated by descendant loggers will not be filtered by a logger’s filter setting,
unless the filter has also been applied to those descendant loggers."
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