Json encode from __repr__, __str__ or __serialize__ when available

[pmithrandir]

Hello,

When I need to json encode a new object or an Enum , I need to either extend str, or build a json decoder to make it compatible with the default json encoder.

When using third parties lib, it might create some difficulties as implementing string is not an option, and the dumps method is not reachable.

If I wanted to do that in java, I would implement in my class a serialize method that would be called by json serializer.

Would it be possible, in the encoder, to allow the usage of either a serialize(self) method, or to directly use repr or str when the object after all other option failed.

cpython/Lib/json/encoder.py

Line 192 in a34e4db

if isinstance(o, str):

That will give the final developer a reliable way to explain the json encoder how to interpret the object and serialize it.

[sobolevn]

Please, start a new discussion on https://discuss.python.org/c/ideas/6
But, I guess this was already discussed.

You can do that if you want:

1. Create your own https://docs.python.org/3/library/json.html#json.JSONEncoder and Decoder if you want
2. Make them call __json_encode__ and __json_decode__ magic method that you can define on any objects (or even monkey-patch them to existing ones)
3. Done! :)

I will close this for now, you can follow up this issue with the discussion link! 👍

[ronaldoussoren]

This is a duplicate of #71549. That issue proposes a different method (__json__ instead of __serialize__).

The other issue also doesn't propose a fallback to __repr__ or __str__, but IMHO that would be a bug magnet.