如何在 Python 中记录源文件名和行号

Question

是否可以装饰/扩展python标准日志记录系统，以便在调用日志记录方法时它还会记录文件和调用它的行号或者调用它的方法？

Answer 1

Sure, check formatters in logging docs. Specifically the lineno and pathname variables.

%(pathname)s Full pathname of the source file where the logging call was issued(if available).

%(filename)s Filename portion of pathname.

%(module)s Module (name portion of filename).

%(funcName)s Name of function containing the logging call.

%(lineno)d Source line number where the logging call was issued (if available).

Looks something like this:

formatter = logging.Formatter('[%(asctime)s] p%(process)s {%(pathname)s:%(lineno)d} %(levelname)s - %(message)s','%m-%d %H:%M:%S')

Answer 2

On top of Seb's very useful answer , here is a handy code snippet that demonstrates the logger usage with a reasonable format:

#!/usr/bin/env python
import logging

logging.basicConfig(format='%(asctime)s,%(msecs)d %(levelname)-8s [%(filename)s:%(lineno)d] %(message)s',
    datefmt='%Y-%m-%d:%H:%M:%S',
    level=logging.DEBUG)

logger = logging.getLogger(__name__)
logger.debug("This is a debug log")
logger.info("This is an info log")
logger.critical("This is critical")
logger.error("An error occurred")

Generates this output:

2017-06-06:17:07:02,158 DEBUG    [log.py:11] This is a debug log
2017-06-06:17:07:02,158 INFO     [log.py:12] This is an info log
2017-06-06:17:07:02,158 CRITICAL [log.py:13] This is critical
2017-06-06:17:07:02,158 ERROR    [log.py:14] An error occurred

Answer 3

# your imports above ...


logging.basicConfig(
    format='%(asctime)s,%(msecs)d %(levelname)-8s [%(pathname)s:%(lineno)d in 
    function %(funcName)s] %(message)s',
    datefmt='%Y-%m-%d:%H:%M:%S',
    level=logging.DEBUG
)

logger = logging.getLogger(__name__)

# your classes and methods below ...
# A very naive sample of usage:
try:
    logger.info('Sample of info log')
    # your code here
except Exception as e:
    logger.error(e)

Different from the other answers, this will log the full path of file and the function name that might have occurred an error. This is useful if you have a project with more than one module and several files with the same name distributed in these modules.

Answer 4

To build on the above in a way that sends debug logging to standard out:

import logging
import sys

root = logging.getLogger()
root.setLevel(logging.DEBUG)

ch = logging.StreamHandler(sys.stdout)
ch.setLevel(logging.DEBUG)
FORMAT = "[%(filename)s:%(lineno)s - %(funcName)20s() ] %(message)s"
formatter = logging.Formatter(FORMAT)
ch.setFormatter(formatter)
root.addHandler(ch)

logging.debug("I am sent to standard out.")

Putting the above into a file called debug_logging_example.py produces the output:

[debug_logging_example.py:14 -             <module>() ] I am sent to standard out.

Then if you want to turn off logging comment out root.setLevel(logging.DEBUG) .

For single files (eg class assignments) I've found this a far better way of doing this as opposed to using print() statements. Where it allows you to turn the debug output off in a single place before you submit it.

Answer 5

For devs using PyCharm or Eclipse pydev, the following will produce a link to the source of the log statement in the console log output:

import logging, sys, os
logging.basicConfig(stream=sys.stdout, level=logging.DEBUG, format='%(message)s | \'%(name)s:%(lineno)s\'')
log = logging.getLogger(os.path.basename(__file__))


log.debug("hello logging linked to source")

See Pydev source file hyperlinks in Eclipse console for longer discussion and history.

Answer 6

If the logger is set with the GetLogger(name) option, where the name is a name that you specified you can also format the logger using %(name)s . You can specify a different name in every file with the GetLogger function, and when a log is produced you will know from which file comes through the name you set.

Example:

import logging

logging.getLogger("main")
logging.basicConfig(#filename=log_fpath, 
                    level=log_level,
                    format='[%(asctime)s] src:%(name)s %(levelname)s:%(message)s',
                    handlers=[logging.FileHandler(log_fpath)])