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Errors & debugging

Handle failures gracefully, raise helpful errors, and debug with confidence.

3 matches

How to Dump a Debugging Repr for Unknown Types in Python

Build a fallback repr that shows dataclass fields or object attributes for any value, handy when debugging unknown types.

debugging repr dataclasses

Python

import dataclasses
from typing import Any


@dataclasses.dataclass
class Sample:
    name: str
    values: list[int]


def dump_repr(obj: Any) -> str:
    """Return a concise but complete repr for debugging unknown types."""
    if dataclasses.is_dataclass(obj):
        fields = ", ".join(
            f"{field.name}={…

12 0 Open

Errors & debugging easy

How to Validate JSON in Python and Catch JSONDecodeError

A robust Python function that attempts to parse JSON strings and returns a boolean plus either the parsed data or a descriptive error message when decoding fails.

json validation jsondecodeerror

Python

import json

def validate_json(json_string):
    """Try to parse JSON, return (is_valid, data_or_error)."""
    try:
        data = json.loads(json_string)
        return True, data
    except json.JSONDecodeError as e:
        return False, f"Invalid JSON: {e}"

if __name__ == "__main__":
    test_inputs = [
        …

11 0 Open

Errors & debugging easy

How to check for None and raise helpful errors in Python

A defensive function that explicitly validates data, keys, and values — raising descriptive ValueError and KeyError exceptions before returning a result.

none error-handling validation

Python

def get_value(data, key):
    if data is None:
        raise ValueError("data cannot be None")
    if key not in data:
        raise KeyError(f"key '{key}' not found in data")
    result = data[key]
    if result is None:
        raise ValueError(f"value for key '{key}' is None")
    return result


if __name__ == "__…

15 0 Open

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