Allow custom serializers

[XayOn]

The hability to specify a custom serializer for a file could be useful to save files in human-readable serializable formats such as the one followed by splunk. This would also open a door to save pickled, xml or any other log format the user wants (for whatever reason... I cant think of a good one to save pickled data or xml in logs tbh).

Should be simple enough. I'm proposing a backwards-compatible implementation where serializer is either a boolean, or a custom serializer directly.

loguru/loguru/_handler.py

Line 258 in 1b41299

return json.dumps(serializable, default=str) + "\n"

[XayOn]

I'm leaving this idea here, but will come back tomorrow with a pull request for this proposal 😃

[XayOn]

I was thinking on using a custom sink with serialize=True, that would serve the same purpose except I would have to de-serialize each time and the overhead would be terrific 😞

[Delgan]

Hi! Thanks for your interest on loguru and thanks for being willing to contribute.

This feature has been requested several times but so far I have always been reluctant to add it.
The most recent discussion on this topic: #339 (comment)

I don't know if you saw it but there exists a snippet in the documentation: Serializing log messages using a custom function

I think using a custom formatter is not too cumbersome and should be the way to go. I prefer suggesting this solution over complicating the serialize parameter.

def formatter(record):
    record["extra"]["serialized"] = orjson.dumps(record, default=str)
    return "{extra[serialized]}\n"

logger.add("file.log", format=formatter)

In this way, the user has the possibility to customize the serialization process entirely.

[XayOn]

The patch() function is actually better for what I was looking for!
I thought I read enough on the documentation but I missed that part.

Thanks and thanks for this great library!

[Delgan]

Thanks for your understanding, @XayOn!