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+--- Thread: Why does json.dumps sometimes fail to serialize my Python object? or How can I customize the output f (/thread-why-does-json-dumps-sometimes-fail-to-serialize-my-python-object-or-how-can-i-customize-the-output-f)
Why does json.dumps sometimes fail to serialize my Python object? or How can I customize the output f - proxyZed77 - 09-05-2024
"Ugh, why does json.dumps keep failing on my custom objects??"
Seriously tho, I keep getting this "TypeError: Object not JSON serializable" nonsense. Like, I get it—json.dumps can't magically handle *everything*, but c'mon.
Is there a secret trick to make it work? Do I *have* to write a custom encoder every time? Feels like overkill for a simple debug dump.
Also, why does it work fine for some objects but choke on others? Python, pls.
(And yes, I googled. Still confused.)
---
*Side note: if you’ve got a quick fix or a dirty workaround, I’m all ears. Pretty please?*
“” - secretByte77 - 05-11-2024
Ah, the classic json.dumps struggle. The error happens because Python's JSON module only handles basic types (dicts, lists, strings, etc.).
For custom objects, you gotta either:
1) Convert them to a dict first (like `obj.__dict__` if it's a class), or
2) Use `default=` in json.dumps to specify how to serialize weird stuff.
Quick dirty fix? `json.dumps(your_obj, default=lambda o: o.__dict__)`
Not perfect, but gets the job done for debugging!
“” - webDiver77 - 05-01-2025
lol yeah json.dumps is picky af.
If you don’t wanna write a full encoder, just override `__str__` or `__repr__` in your class to return something json-friendly. Then do `json.dumps(str(your_obj))`.
Not elegant, but hey, it’s a debug dump—who cares?
“” - dataVoyX99 - 08-01-2025
Ugh, I feel your pain. json.dumps is like that one friend who only eats plain pizza.
Pro tip: Check out the `dataclasses` module if you’re on Python 3.7+. `@dataclass` objects play nice with json.dumps if you use `asdict()` from the `dataclass` module first.
Example:
```python
from dataclasses import asdict
json.dumps(asdict(your_dataclass_obj))
```
Life-changer.
“” - ghostLeap99 - 20-02-2025
The error’s annoying, but it’s not json.dumps’ fault—JSON itself doesn’t support custom types.
If you’re lazy (like me), try `json.dumps(your_obj, default=vars)`. Works if your object’s attributes are simple.
For more control, yeah, you’ll need a custom encoder. Or just use `pickle` if it’s for internal stuff (but don’t use pickle for APIs, obvs).
“” - cloakXpertX - 08-03-2025
json.dumps failing? Classic.
If you’re dealing with datetime or other non-serializable types, `str()` them first. Or use `default=str` in json.dumps as a band-aid.
For a proper fix, though, `json.JSONEncoder` subclass is the way. Annoying, but reusable!
“” - WebPhantom99 - 21-03-2025
Dude, same. json.dumps is *so* finicky.
Try this hack: `json.dumps(your_obj, default=lambda x: str(x) if hasattr(x, '__str__') else None)`
It’ll at least give you *something* instead of crashing. Not ideal for prod, but great for debugging.
“” - ProxyXplorerX - 23-03-2025
The struggle is real. json.dumps won’t magically know how to serialize your custom class.
Quick fix: Add a `to_json()` method to your class that returns a dict. Then do `json.dumps(your_obj.to_json())`.
Or, if you’re feeling fancy, use `marshmallow` or `pydantic` for proper serialization. Overkill for debugging, though.
“” - proxyZed77 - 27-03-2025
Thanks for all the tips! The `default=lambda o: o.__dict__` trick worked like a charm for debugging.
Still kinda wild that json.dumps doesn’t have a built-in "just try your best" mode, tho.
Quick Q: Anyone know why some objects serialize fine without __dict__? Like, why does it work sometimes and not others? Is there a hidden rule?
“” - ProxyDrift77 - 29-03-2025
json.dumps is like that one teacher who only accepts homework in *exactly* the right format.
For a dirty workaround, just `print(vars(your_obj))` and copy-paste into a dict. Not scalable, but gets you unstuck.
For a real solution, yeah, custom encoder or a lib like `simplejson` (handles more types out of the box).