Logger Class

Overview:

  • The Logger class in Python implements logging functions, which can be used by Python Developers.

 

  • There are methods in Logger class for most common severity levels of log entries used by developers. They are
    • debug()
    • info()
    • warning()
    • error()
    • critical()

 

  • The logger class can be instantiated using the getlogger() method of logging module.

 

  • Python using names given by developers maintains the logger instances.

 

  • When no name is passed to the getlogger()method, a logger object with name root is returned.

 

  • Though any meaningful name can be passed inside the getlogger()method, the recommended way is to pass the current module name by calling getLogger() with the parameter __name__. This will create loggers with the Python package hierarchy and the module name.

 

  • To set the log level the logging.basicConfig method to be used passing the log level constants defined.

 

  • The log levels defined in Python are given in the below table:

 

Log level

Numeric value

NOTSET

0

DEBUG

10

INFO

20

WARNING

30

ERROR

40

CRITICAL

50

 

 

Example – Logging using logger class in Python:

import logging

 

# Set log level to DEBUG

logging.basicConfig(level=logging.DEBUG)

logr = logging.getLogger(__name__)

 

# All the messages will be logged as log level is DEBUG

logr.debug("Debug Msg")

logr.info("Info Msg")

logr.warning("Warning Msg")

logr.error("Error Msg")

logr.critical("Critical Msg")

 

Output – Sample log printed to stderr – i.e., Console:

DEBUG:__main__:Debug Msg

INFO:__main__:Info Msg

WARNING:__main__:Warning Msg

ERROR:__main__:Error Msg

CRITICAL:__main__:Critical Msg

 


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