Handlers - Python logging

To remedy that, we have to talk about the second concept, handlers. A logger can have multiple handlers assigned, by default it has none. The main purpose of a handler is directing a LogRecord to an output.

The most common one is the StreamHandler, which print logs to your console.

stream_handler = logging.StreamHandler()
logger.addHandler(stream_handler)

And the FileHandler, which writes logs to a file.

file_handler = logging.FileHandler("mylog.log")
logger.addHandler(file_handler)

Of course, you can also write your own handlers by extending the logging.Handler class and implementing the emit method. You can do whatever you want, here is a log handler that sends every message to an API.

class CustomHandler(logging.Handler):
	def emit(self, record: logging.LogRecord):
		import json
		import requests

		requests.post(
			"https://my_endpoint.io/logs",
			json={"level": record.levelname, "message": record.getMessage()},
		)

logger.addHandler(CustomHandler())

Chapter 3: Handlers

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