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Errors & debugging

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

4 matches

How to Add a Correlation ID to Logging Records in Python

Attach a unique correlation ID to every log record using a custom logging.Filter, making distributed request tracking traceable.

logging correlation-id filter

Python

import logging
import uuid
from dataclasses import dataclass, field


@dataclass
class CorrelationIdFilter(logging.Filter):
    correlation_id: str = field(default_factory=lambda: str(uuid.uuid4()))

    def filter(self, record: logging.LogRecord) -> bool:
        record.correlation_id = self.correlation_id
        re…

15 0 Open

Errors & debugging easy

How to Mock a Failing Dependency to Test Error Paths in Python

Inject a fake HTTP client that raises a connection error to test how code handles dependency failures without touching the network.

testing mocking requests

Python

import requests

def fetch_user(user_id):
    url = f"https://api.example.com/users/{user_id}"
    response = requests.get(url, timeout=5)
    response.raise_for_status()
    return response.json()

def get_user_name(user_id, http_client):
    try:
        user_data = http_client(user_id)
        return user_data["nam…

16 0 Open

Errors & debugging easy

How to Record Last N Errors with a Ring Buffer in Python

Use collections.deque with maxlen to keep only the most recent N error messages while discarding older entries automatically.

ring-buffer deque error-handling

Python

import collections

class ErrorRecorder:
    def __init__(self, size):
        self.buffer = collections.deque(maxlen=size)

    def record_error(self, message):
        self.buffer.append(message)

    def get_errors(self):
        return list(self.buffer)

if __name__ == "__main__":
    recorder = ErrorRecorder(3)
 …

13 0 Open

Errors & debugging medium

How to attach a request ID to exception messages in Python

This code shows how to enrich exception messages with contextual request IDs using context variables, making error logs more traceable across concurrent requests.

contextvars exception-handling logging

Python

import logging
from contextvars import ContextVar

request_id_var = ContextVar("request_id", default="unknown")

def add_request_id(exc: Exception) -> Exception:
    exc.args = (f"request_id={request_id_var.get()} | {exc.args[0]}" if exc.args else f"request_id={request_id_var.get()}",) + exc.args[1:]
    return exc

d…

12 0 Open

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