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Errors & debugging

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

6 matches

How to Catch KeyError with a Default Value in Python Dictionaries

Safely retrieve dictionary values while catching KeyError and handling None values by returning a default.

def get_value(data, key, default=None):
    """
    Safely get a value from a dictionary, returning a default if the key
    is missing or the value is None.
    """
    try:
        value = data[key]
        return value if value is not None else default
    except KeyError:
        return default


if __name__ == "_…

14 0 Open

Errors & debugging easy

How to Serialize an Exception to a JSON-Safe Dict in Python

Convert any Python exception into a JSON-safe dictionary with type, message, and the last few traceback lines for logging.

exceptions json logging

Python

import json
import traceback
from typing import Any


def exception_to_dict(exc: Exception) -> dict[str, Any]:
    """Convert an exception into a JSON-safe dictionary."""
    return {
        "type": type(exc).__name__,
        "message": str(exc),
        "traceback": traceback.format_exc().strip().split("\n")[-3:],
…

15 0 Open

Errors & debugging easy

How to Use Optional Return in Python Instead of Raising Exceptions

A Python function returns None for missing dictionary keys instead of raising KeyError, enabling graceful lookup handling with type hints.

optional typing dict-get

Python

from typing import Optional


def find_user(users: dict, user_id: int) -> Optional[dict]:
    """
    Look up a user by ID. Returns the user dict if found,
    otherwise returns None instead of raising KeyError.
    """
    return users.get(user_id)


def main() -> None:
    users = {
        1: {"name": "Alice", "ema…

14 0 Open

Errors & debugging easy

Map Exception Type to HTTP Status Code in Python

Maps Python exception types to appropriate HTTP status codes using a dictionary lookup for consistent API error handling.

exceptions http-status error-handling

Python

EXCEPTION_STATUS_MAP = {
    ValueError: 400,
    KeyError: 400,
    TypeError: 400,
    PermissionError: 403,
    FileNotFoundError: 404,
    AttributeError: 404,
    TimeoutError: 408,
    NotImplementedError: 501,
    ConnectionError: 503,
}


def status_code_for(exception_type):
    try:
        return EXCEPTION_S…

13 0 Open

Errors & debugging easy

Python dict try-except KeyError EAFP vs LBYL

Compare EAFP (try-except) and LBYL (if-in-check) styles for safely accessing dictionary keys, with working examples in Python.

eafp lbyl dictionary

Python

def safe_get_lbyl(d, key):
    if key in d:
        return d[key]
    return "default-lbyl"

def safe_get_eafp(d, key):
    try:
        return d[key]
    except KeyError:
        return "default-eafp"

if __name__ == "__main__":
    data = {"name": "Alice", "age": 30}
    print("LBYL:", safe_get_lbyl(data, "missing")…

14 0 Open

Errors & debugging easy

Use pprint for Nested Structure Debug Output in Python

Pretty-print nested dictionaries and lists with pprint for readable, organized debug output.

pprint debugging nested-structure

Python

from pprint import pprint

def build_nested_structure():
    """Create a sample nested data structure for demonstration."""
    return {
        "project": "DataPipeline",
        "config": {
            "inputs": ["raw_1.json", "raw_2.json"],
            "processing": {
                "steps": ["clean", "transform",…

15 0 Open

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