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+--- Thread: How to Handle jpython json.dumps Annotation Data Type Correctly? or What’s the Best Way to Annotate D (/thread-how-to-handle-jpython-json-dumps-annotation-data-type-correctly-or-what%E2%80%99s-the-best-way-to-annotate-d)
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How to Handle jpython json.dumps Annotation Data Type Correctly? or What’s the Best Way to Annotate D - secureVoy77 - 10-06-2024
"Struggling with jpython json.dumps annotation data type – any tips?"
Hey folks!
So I’ve been messing around with jpython json.dumps and keep hitting snags with the annotation data type stuff. Like, it *kinda* works but sometimes throws weird errors or misformats things.
Anyone else run into this?
Specifically, how do you handle custom types or nested data without it freaking out? I’ve tried a few hacks, but feels like I’m missing something obvious.
Also, does jpython json.dumps annotation data type even support custom classes, or do I gotta serialize everything manually?
Appreciate any pointers—thanks in advance!
(PS: sorry for typos, typing this on my phone lol)
“” - ghostlyTrekkerX - 29-09-2024
Hey! I ran into the same issue with jpython json.dumps annotation data type last week.
Turns out, it doesn’t handle custom classes out of the box. You gotta write a custom encoder.
Here’s a quick fix:
```python
class CustomEncoder(json.JSONEncoder):
def default(self, obj):
if hasattr(obj, '__dict__'):
return obj.__dict__
return super().default(obj)
```
Then pass it like `json.dumps(your_data, cls=CustomEncoder)`.
Works like a charm for nested stuff too!
“” - darkXchangeX - 11-03-2025
Ugh, jpython json.dumps annotation data type can be such a pain with nested data.
I found this tool called `pydantic`—it’s a lifesaver for serialization. Lets you define models with types, and it handles the json conversion automatically.
Check it out:
https://pydantic-docs.helpmanual.io/
Saved me hours of headache.
“” - stealthDashX77 - 19-03-2025
Yeah, jpython json.dumps annotation data type is picky.
If you’re dealing with custom classes, you might wanna try `dataclasses` + `asdict()` from the `dataclasses` module.
```python
from dataclasses import asdict, dataclass
@dataclass
class YourClass:
field1: str
field2: int
data = YourClass("test", 123)
json.dumps(asdict(data))
```
Super clean and no extra encoder needed.
“” - shadowJumpX77 - 24-03-2025
Pro tip: Skip the hassle and use `orjson` instead of the built-in json module.
It’s faster and handles way more types natively. Just `pip install orjson` and replace `json.dumps` with `orjson.dumps`.
Works great with jpython json.dumps annotation data type issues.
Docs here: https://github.com/ijl/orjson
“” - GhostNet99 - 01-04-2025
Man, I feel you. jpython json.dumps annotation data type errors are the worst.
For custom classes, I just add a `to_json()` method to my classes.
```python
def to_json(self):
return {k: v for k, v in self.__dict__.items() if not k.startswith('_')}
```
Then call it before dumping. Not perfect, but gets the job done.
“” - deepScreenX - 01-04-2025
Hey! Had the same problem.
If you’re using jpython json.dumps annotation data type, try `jsonpickle`. It serializes *everything*, even weird custom objects.
```python
import jsonpickle
jsonpickle.dumps(your_object)
```
Might be overkill, but it works when nothing else does.
“” - garibank_77 - 03-04-2025
For nested data, I’ve had luck with `marshmallow`.
It’s a bit more setup, but once you define schemas, jpython json.dumps annotation data type becomes a non-issue.
https://marshmallow.readthedocs.io/
Steep learning curve, but worth it for complex stuff.
“” - secureVoy77 - 04-04-2025
Wow, thanks everyone!
Didn’t expect so many solutions. Tried the `CustomEncoder` and it worked for my basic case, but `orjson` looks tempting for speed.
Quick Q: Anyone know if `orjson` plays nice with jpython json.dumps annotation data type in nested custom classes? Or do I still need a custom handler?
(Also, gonna check out `pydantic`—sounds like magic.)
Thanks again!
“” - fastDashX77 - 04-04-2025
jpython json.dumps annotation data type struggles are real lol.
If you’re lazy like me, just convert everything to dicts first.
```python
import json
from typing import Any
def to_serializable(val: Any) -> Any:
if hasattr(val, '__dict__'):
return {k: to_serializable(v) for k, v in val.__dict__.items()}
return val
json.dumps(to_serializable(your_data))
```
Not elegant, but ¯\_(ツ)_/¯