Intermediate code explainers

go

func ProxyDownload(c *gin.Context) {
	objectKey := c.Param("key")
	upstream := fmt.Sprintf("%s/files/%s", storageBaseURL, objectKey)

Streaming a proxied download in Gin

reverse-proxy streaming http-headers

Intermediate 8 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

javascript

function curry(fn) {
  return function curried(...args) {
    if (args.length >= fn.length) {
      return fn.apply(this, args);

Building a curry function in JavaScript

currying closures higher-order-functions

Intermediate 7 steps

rust

use std::time::Duration;
 
use axum::{
    extract::State,

Rate-limit errors as Axum responses

error-handling rate-limiting http-headers

Intermediate 6 steps

typescript

import { Injectable } from '@angular/core';
import { CanDeactivateFn } from '@angular/router';
import { inject } from '@angular/core';
import { MatDialog } from '@angular/material/dialog';

Guarding navigation with CanDeactivate in Angular

route-guards functional-guards dependency-injection

Intermediate 7 steps

go

package handlers
 
import (
	"net/http"

Header-driven API versioning in Gin

api-versioning header-binding closures

Intermediate 6 steps

php

<?php
 
namespace App\Services;

Managing many-to-many tags in Laravel

many-to-many pivot-table collections

Intermediate 9 steps

ruby

class ApplicationJob < ActiveJob::Base
  retry_on ActiveRecord::Deadlocked, wait: 5.seconds, attempts: 3
  discard_on ActiveJob::DeserializationError

Instrumenting every job in Rails

active-job structured-logging retries

Intermediate 6 steps

go

func ListArticles(db *gorm.DB) gin.HandlerFunc {
	return func(c *gin.Context) {
		page, err := strconv.Atoi(c.DefaultQuery("page", "1"))
		if err != nil || page < 1 {

Building a paginated list endpoint in Gin

pagination query-parameters input-validation

Intermediate 8 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

java

package com.example.payments.config;
 
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;

Configuring a Stripe RestClient in Spring

dependency-injection http-client configuration

Intermediate 7 steps

ruby

class PasswordResetsController < ApplicationController
  RESET_PURPOSE = :password_reset
  RESET_EXPIRY = 15.minutes

Password resets with signed global IDs in Rails

authentication signed-tokens global-id

Intermediate 9 steps

javascript

import { useState } from 'react';
 
const steps = ['account', 'profile', 'review'];

Building a multi-step form wizard hook in React

custom-hooks form-validation state-management

Intermediate 9 steps

rust

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

Prometheus request metrics in Axum

middleware observability prometheus

Intermediate 7 steps

typescript

function* map<T, U>(source: Iterable<T>, fn: (value: T, index: number) => U): Generator<U> {
  let index = 0;
  for (const value of source) {
    yield fn(value, index++);

Building a lazy iterator pipeline in TypeScript

generators lazy-evaluation iterators

Intermediate 7 steps

go

package parser
 
import (
	"fmt"

Parsing access logs with named regex groups in Go

regex named-groups parsing

Intermediate 5 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

java

public class GitHubUserClient {
 
    private final HttpClient http = HttpClient.newBuilder()
            .connectTimeout(Duration.ofSeconds(10))

Calling the GitHub API with Java's HttpClient

http-client json-deserialization error-handling

Intermediate 9 steps