Python code explainers

python

import time
 
from flask import Flask, g, request

Timing requests with Flask hooks

middleware request-lifecycle instrumentation

Intermediate 5 steps

python

from pathlib import Path
 
from PIL import Image, ImageOps

Batch image resizing with Pillow

image-processing batch-jobs error-handling

Intermediate 8 steps

python

import base64
import hashlib
import hmac
import json

Building signed expiring tokens with HMAC

hmac authentication base64

Intermediate 7 steps

python

from decimal import Decimal, ROUND_HALF_UP
 
from babel.numbers import format_currency
from flask import Flask

Building a currency Jinja filter in Flask

template filters decimal precision internationalization

Intermediate 6 steps

python

from functools import wraps
 
import jwt
from flask import current_app, g, jsonify, request

How a JWT auth decorator works in Flask

decorators authentication jwt

Intermediate 6 steps

python

from django.contrib import admin
from django.utils import timezone
from django.utils.html import format_html

Custom columns in the Django admin

admin-customization computed-columns html-rendering

Intermediate 7 steps

python

from collections import defaultdict
from datetime import datetime
from openpyxl import load_workbook

Summarizing an Excel sheet with openpyxl

excel-parsing aggregation type-dispatch

Intermediate 7 steps

python

from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic import ListView
 
from .models import Invoice

Building a scoped, filtered ListView in Django

class-based views queryset filtering authentication

Intermediate 7 steps

python

import click
 
 
@click.command()

Building a typed CLI with Click

cli decorators validation

Intermediate 7 steps

python

import csv
 
from django.http import StreamingHttpResponse
from django.utils.timezone import now

Streaming a CSV export in Django

streaming csv-export generators

Intermediate 7 steps

python

from pathlib import Path
 
import chardet

Reading text files of unknown encoding in Python

encoding byte-order-mark fallback

Intermediate 8 steps

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