Python code explainers

python

import logging
import uuid
from flask import Flask, request, g

Adding correlation IDs to Flask logs

logging request-lifecycle observability

Intermediate 7 steps

python

import random
from dataclasses import dataclass

Weighted loot drops in Python

weighted-random dataclasses sampling

Intermediate 7 steps

python

from datetime import datetime
 
from flask import Blueprint, abort, redirect, request
from sqlalchemy import func

Building a URL shortener redirect in Flask

routing url-shortener orm

Intermediate 6 steps

python

import csv
import io
from typing import Annotated

Content negotiation in FastAPI

content-negotiation dependency-injection http-headers

Intermediate 5 steps

python

from decimal import Decimal
from typing import Annotated
 
from fastapi import APIRouter, status

Cross-field order validation in FastAPI

validation pydantic-models decimal-money

Intermediate 7 steps

python

from functools import wraps
from flask import request, jsonify

A parameterized query-param decorator in Flask

decorators validation type-casting

Intermediate 8 steps

python

from fastapi import APIRouter, status
from fastapi.responses import JSONResponse
from sqlalchemy import text
from sqlalchemy.exc import SQLAlchemyError

Liveness vs readiness health checks in FastAPI

health-checks dependency-injection async

Intermediate 6 steps

python

from typing import Optional
 
from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel, EmailStr, Field

How PATCH partial updates work in FastAPI

partial-update validation dependency-injection

Intermediate 8 steps

python

from fastapi import APIRouter, Depends, HTTPException, status
from pydantic import BaseModel
 
from .dependencies import get_current_user, get_project_service

Building a CRUD router with FastAPI

dependency-injection rest-api authentication

Intermediate 6 steps

python

from flask import Blueprint, render_template, request, redirect, url_for, flash, abort
from .models import User, AuditLog
from .extensions import db
from .decorators import admin_required

Nesting Flask Blueprints for an admin panel

blueprints route-guards pagination

Intermediate 8 steps

python

from xml.etree import ElementTree as ET
from xml.dom import minidom

Converting nested dicts to XML in Python

recursion serialization xml

Intermediate 9 steps

python

from django.db import transaction
from django.db.models import F
from django.http import JsonResponse
from django.views.decorators.http import require_POST

Safely reordering tasks with a Django action

transactions row-locking validation

Advanced 8 steps

python

import os
from uuid import uuid4
 
from flask import Blueprint, current_app, jsonify, request, url_for

How a Flask image upload endpoint works

file-upload validation image-processing

Intermediate 9 steps

python

from flask import g, session
 
from .extensions import cache
from .models import User

Injecting the current user in Flask templates

context-processor caching authentication

Intermediate 6 steps

python

import heapq
 
 
class MovingMedian:

Running median with two heaps

heaps streaming invariants

Advanced 8 steps

python

import json
import logging
import threading
from pathlib import Path

A hot-reloading config file watcher

file-watching thread-safety hot-reload

Intermediate 7 steps

python

class Parser:
    def __init__(self, text):
        self.tokens = self._tokenize(text)
        self.pos = 0

A recursive descent arithmetic parser

recursive-descent tokenizer operator-precedence

Intermediate 9 steps

python

import re
from dataclasses import dataclass, field

Building a table of contents from Markdown

regular-expressions parsing slugification

Intermediate 9 steps