Replace newline `\n` with literal `\\n` in log

I’d love the option to force log messages to span just one line by replacing \n with \\n.

This is an issue which are sometimes encountered when logging Pandas DataFrames and Numpy Arrays.

[Delgan]

Yep, that’s totally possible. Instead of modifying record["message"], just create a new entry to be used by the format parameter of some specific sinks only.

def flatten_message(record):
    record["extra"]["flattened_message"] = record["message"].replace("\n", "\\n")

logger.add("file.log", format="[{time}] {extra[flattened_message]}")
logger = logger.patch(flatten_message)

[Delgan]

Oh, yeah, sorry, I completely misinterpreted your question.

So, here is another workaround I can offer you. 😄

>>> from loguru import logger
>>> multi = "foo\nbar\nbaz\n"
>>> logger.info(multi)
2020-01-11 17:32:33.496 | INFO - __main__ - foo
bar
baz

>>> def flatten_message(record):
...     record["message"] = record["message"].replace("\n", "\\n")
... 
>>> logger = logger.patch(flatten_message)
>>> logger.info(multi)
2020-01-11 17:33:16.592 | INFO - __main__ - foo\nbar\nbaz\n

I think you can use patch() to force the message to span only one line. You can also apply the change for your whole application by using the patcher parameter of the configure() method.