Python code explainers

python

from flask import Blueprint, jsonify, request, abort
from flask_caching import Cache
 
cache = Cache(config={"CACHE_TYPE": "RedisCache", "CACHE_REDIS_URL": "redis://localhost:6379/0"})

Custom cache keys for Flask endpoints

caching redis cache-invalidation

Intermediate 7 steps

python

from fastapi import APIRouter, FastAPI, HTTPException
from pydantic import BaseModel

Versioning a FastAPI API with mounted sub-apps

api-versioning response-models sub-applications

Intermediate 6 steps

python

import re
import unicodedata
 
_SLUG_STRIP = re.compile(r"[^\w\s-]")

Building URL-safe slugs in Python

string-processing regex unicode-normalization

Intermediate 7 steps

python

import os
import tarfile
from pathlib import Path

Safely compressing and extracting tar.gz archives

file-io compression path-traversal

Intermediate 6 steps

python

from collections import OrderedDict
from typing import Any, Hashable, Optional

Building an LRU cache with OrderedDict

caching eviction data-structures

Intermediate 6 steps

python

from flask import Flask, g, jsonify, request, abort
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker

Per-request SQLAlchemy sessions in Flask

database sessions request lifecycle connection management

Intermediate 7 steps

python

from fastapi import APIRouter, Depends, Response, status
from sqlalchemy.orm import Session
 
from .database import get_db

Building a REST article resource in FastAPI

dependency injection rest api orm

Intermediate 8 steps

python

from functools import wraps
from flask import Blueprint, session, request, redirect, url_for, flash, render_template
from werkzeug.security import check_password_hash

Session-based auth with a Flask Blueprint

authentication decorators sessions

Intermediate 9 steps

python

import logging
import re

Redacting secrets in Python log records

logging regex redaction

Intermediate 7 steps

python

import asyncio
import logging
from contextlib import asynccontextmanager
from datetime import datetime, timedelta, timezone

A background session cleaner in FastAPI

background-tasks asyncio lifespan

Intermediate 8 steps

python

import bisect
from typing import Sequence

Computing latency percentiles in Python

percentiles interpolation binary-search

Intermediate 8 steps

python

from datetime import date
from enum import Enum
from typing import Annotated

Reusable query params with Pydantic in FastAPI

query-parameters validation pagination

Intermediate 8 steps

python

import csv
from pathlib import Path

Splitting a large CSV into smaller files

file-io streaming csv

Intermediate 8 steps

python

from functools import wraps
 
from django.core.cache import cache
from django.http import JsonResponse

Building a rate-limit decorator in Django

decorators rate limiting caching

Intermediate 7 steps

python

import os
import time
from pathlib import Path

Polling a directory for file changes in Python

polling filesystem set-operations

Intermediate 8 steps

python

from decimal import Decimal
 
from django.db import transaction
from django.core.exceptions import ValidationError

Placing an order atomically in Django

transactions row-locking concurrency

Advanced 9 steps

python

import os
from dataclasses import dataclass
from functools import lru_cache

Loading typed config from environment variables

configuration environment-variables type-coercion

Intermediate 6 steps

python

import hashlib
from pathlib import Path

Streaming SHA-256 checksums in Python

hashing file-io streaming

Intermediate 6 steps