Cannot log to stream in Python

Question

I want to log to stream of io.StringIO, but end up with empty stream. Here is my code:

import logging, io

log_handler = logging.StreamHandler(stream)
log_format = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
log_handler.setFormatter(log_format)
log_handler.setLevel(logging.INFO)

logger.addHandler(log_handler)

logger.info("This is test info log")
print(stream.getvalue())

What am I doing wrong?

UPDATE It seems to be working if I replace level with "Warning" like this

log_handler.setLevel(logging.WARNING)
logger.warning("This is test info log")

It also prints into console for some reason

Apparently, I needed logger.setLevel(logging.INFO). One can set level on logger and handler separately. Here is the link: docs.python.org/3.8/howto/… — user1700890
– user1700890, Commented Jan 6, 2023 at 18:39
Here is useful discussion: stackoverflow.com/questions/6614078/… — user1700890
– user1700890, Commented Jan 6, 2023 at 18:39

Vallari Agrawal · Accepted Answer · 2023-01-07 14:53:34Z

1

Configure the root logger: logging.basicConfig(level=logging.DEBUG).

Then you can set log_handler.setLevel(logging.INFO) to whatever level you wish, it will capture logs to stream accordingly.

answered Jan 7, 2023 at 14:53

Vallari Agrawal

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