Intermediate code explainers

python

from urllib.parse import urlparse, parse_qs
from dataclasses import dataclass, field
 
ALLOWED_SCHEMES = {"http", "https"}

Validating URLs into a safe endpoint in Python

input validation url parsing dataclasses

Intermediate 7 steps

php

final class BitmapGrid
{
    private SplFixedArray $cells;

A flat-array bitmap grid in PHP

data-structures row-major-order bitmap

Intermediate 7 steps

go

func handleUpload(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseMultipartForm(32 << 20); err != nil {
		http.Error(w, "failed to parse form: "+err.Error(), http.StatusBadRequest)
		return

Handling multi-file uploads in Go

multipart file-upload http-handler

Intermediate 9 steps

typescript

import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { BullModule } from '@nestjs/bullmq';

How a NestJS feature module wires up

dependency-injection modularity orm

Intermediate 7 steps

python

from flask import Blueprint, render_template, request, redirect, url_for, flash
from werkzeug.security import check_password_hash
 
from .models import User, db

A change-email route in Flask

blueprints form-validation password-hashing

Intermediate 8 steps

ruby

class DatasetImportJob < ApplicationJob
  queue_as :default
 
  def perform(import)

Streaming import progress with a Rails job

background-jobs turbo-streams progress-tracking

Intermediate 9 steps

rust

use bytes::{Buf, BufMut, BytesMut};
use tokio_util::codec::{Decoder, Encoder};
 
const MAX_FRAME: usize = 8 * 1024 * 1024;

A length-prefixed frame codec in Tokio

framing codecs buffers

Intermediate 8 steps

php

namespace App\Http\Filters;
 
use Closure;
use Illuminate\Database\Eloquent\Builder;

Composable query filters with Laravel's Pipeline

pipeline query-builder single-responsibility

Intermediate 7 steps

go

package render
 
import (
	"net/http"

How Gin renders MsgPack responses

serialization content-type interface-implementation

Intermediate 5 steps

typescript

import {
  Controller,
  Get,
  Query,

Validating paginated queries in NestJS

pagination validation pipes

Intermediate 7 steps

rust

use axum::{
    body::{Body, Bytes},
    extract::Request,
    http::StatusCode,

Logging request bodies in Axum middleware

middleware streaming-body logging

Intermediate 8 steps

java

import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.regex.Pattern;

Ranking the most frequent words in Java

streams regex grouping

Intermediate 7 steps

ruby

class Booking < ApplicationRecord
  belongs_to :room
  belongs_to :guest

Guarding booking dates in a Rails model

validations associations scopes

Intermediate 5 steps

python

import pytest
from fastapi.testclient import TestClient
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

Testing FastAPI routes with dependency overrides

testing fixtures dependency-injection

Intermediate 7 steps

javascript

import { createContext, useContext, useState, useId } from "react";
 
const AccordionContext = createContext(null);
const ItemContext = createContext(null);

Building a compound Accordion in React

context compound-components state-management

Intermediate 8 steps

php

namespace App\Providers;
 
use Illuminate\Database\Query\Builder as QueryBuilder;
use Illuminate\Database\Eloquent\Builder as EloquentBuilder;

Adding a whereActive macro in Laravel

macros service-provider query-builder

Intermediate 5 steps

go

package proxy
 
import (
	"log"

Building a hardened Go reverse proxy

reverse-proxy http timeouts

Intermediate 7 steps

rust

use std::time::Duration;
 
use axum::{
    body::Body,

Turning Axum timeouts into 504 JSON

middleware timeouts error-handling

Intermediate 7 steps