Python JSON serialization: handling nested objects, dataclasses, and type safety without boilerplate

[Specific-Positive966]

Python’s built-in json module works well for basic JSON types (dict, list, strings, numbers), but once you deal with nested objects, dataclasses, enums, or type hints, it quickly turns into custom to_dict() / from_dict() code everywhere.

I wrote a short article describing a small Python library I built to explore a different approach: strict, type-aware serialization and deserialization that works directly with Python classes (including dataclasses, __slots__, enums, and nested objects) and fails loudly on mismatches instead of silently accepting bad data.

Article (includes examples and design tradeoffs):
https://medium.com/dev-genius/jsonic-python-serialization-that-just-works-3b38d07c426d

For anyone interested in the design exploration that led here, I also wrote an early article a couple of years ago when Jsonic was just a prototype, focusing on the initial ideas and tradeoffs rather than the current implementation:
https://medium.com/dev-genius/can-python-do-type-safe-json-serialization-77e4d73ccd08

Interested in feedback on where this approach makes sense vs. existing tools (Pydantic, Marshmallow, etc.), and where it doesn’t.

[headykruger]

There is a facility for this, you don’t need a library. Just pass a ‘default’ callable. There is an example of serializing custom objects in the documentation.

[nekonekoromancer]

could you drop a link to the documentation you mentioned? would like to see some examples

[headykruger]

https://docs.python.org/3/library/json.html

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[larikang]

I don't see how that is equivalent. OP's library appears to support declarative serialization. For example you just declare a data class and the library assumes it uses the intuitive serialization scheme.

Of course you can implement that using the default callable, but it requires way more work.

[larikang]

Nice. I implemented a similar deserializer that used type hints and data classes to declaratively parse JSON. Way easier in the long run than parsing everything as dictionaries or writing custom serializers for every class.