Code Explainers

Browse the library

rust 
use axum::{
    body::Bytes,
    extract::State,
    http::StatusCode,

Handling raw byte uploads in Axum

extractors shared-state request-limits
Intermediate 7 steps
typescript 
import {
  Directive,
  Input,
  TemplateRef,

Building a structural *appUnless directive in Angular

structural-directive template-rendering dependency-injection
Intermediate 8 steps
java 
@Service
public class PaymentGatewayClient {
 
    private static final Logger log = LoggerFactory.getLogger(PaymentGatewayClient.class);

Resilient payment calls with Spring Retry

retry backoff fault-tolerance
Intermediate 7 steps
php 
<?php
 
namespace App\Models\Scopes;
 

How a tenant global scope works in Laravel

multi-tenancy global-scope query-builder
Intermediate 5 steps
javascript 
const RETRIABLE_STATUS = new Set([408, 429, 500, 502, 503, 504]);
 
function sleep(ms, signal) {
  return new Promise((resolve, reject) => {

Retrying fetch with exponential backoff

retry exponential-backoff abort-signal
Advanced 8 steps
go 
package main
 
import (
	"net/http"

How route groups nest in Gin

routing middleware api versioning
Intermediate 6 steps
rust 
use axum::{
    extract::{Query, State},
    http::StatusCode,
    Json,

Paginated, filtered product listing in Axum

pagination query-parameters sql-filtering
Intermediate 8 steps
python 
from operator import itemgetter
 
 
def sort_employees(employees):

Multi-key sorting patterns in Python

sorting tuple-keys itemgetter
Intermediate 5 steps
typescript 
type EventMap = Record<string, unknown[]>;
 
type Listener<Args extends unknown[]> = (...args: Args) => void;
 

A type-safe event emitter in TypeScript

generics mapped-types event-emitter
Advanced 8 steps
java 
public final class Debouncer<T> {
 
    private final ScheduledExecutorService scheduler =
            Executors.newSingleThreadScheduledExecutor(runnable -> {

How a debouncer collapses bursts in Java

debounce concurrency scheduling
Intermediate 9 steps
javascript 
const express = require('express');
const Stripe = require('stripe');
 
const stripe = new Stripe(process.env.STRIPE_SECRET_KEY);

Verifying Stripe webhooks in Express

webhooks signature-verification raw-body
Intermediate 7 steps
ruby 
class Api::V1::ArticlesController < Api::V1::BaseController
  def index
    articles = Article
      .published

Building a JSON:API endpoint in Rails

serialization eager-loading pagination
Intermediate 7 steps
php 
<?php
 
namespace App\Support;
 

Retry with exponential backoff in PHP

retry exponential-backoff error-handling
Intermediate 7 steps
typescript 
import { inject } from '@angular/core';
import { ResolveFn, Router, ActivatedRouteSnapshot } from '@angular/router';
import { catchError, of, EMPTY } from 'rxjs';
import { Article } from './models/article';

Prefetching route data with an Angular resolver

route-resolver dependency-injection rxjs
Intermediate 6 steps
python 
from itertools import islice
from typing import Iterable, Iterator, TypeVar
 
T = TypeVar("T")

Batching an iterable for bulk indexing

generators batching lazy-evaluation
Intermediate 7 steps
rust 
use axum::{
    extract::FromRef,
    http::StatusCode,
    response::{IntoResponse, Redirect},

Signed cookie sessions in Axum

sessions cookies authentication
Intermediate 8 steps
java 
package com.example.logs;
 
import java.io.IOException;
import java.io.UncheckedIOException;

Counting HTTP statuses with Java streams

streams regex file-io
Intermediate 6 steps
ruby 
class FundsTransfer
  class InsufficientFundsError < StandardError; end
 
  def initialize(source:, destination:, amount:)

Atomic money transfers with Rails transactions

service object database transactions row locking
Advanced 9 steps