Code Patterns

Code Patterns Reference

This skill contains comprehensive patterns for modern development. Reference files are organized by topic.

Quick Reference

Reference Files

• api.md - REST, GraphQL, authentication, pagination
• testing.md - pytest, vitest, mocking, coverage
• docker.md - Dockerfiles, Compose, production
• ci-cd.md - GitHub Actions, deployment
• database.md - PostgreSQL, migrations, queries
• typescript.md - Types, generics, advanced patterns
• python.md - async, patterns, best practices
• react.md - Server Components, hooks, Next.js

API Design Quick Reference

REST Endpoints

GET    /resources         List
GET    /resources/{id}    Get one
POST   /resources         Create
PUT    /resources/{id}    Replace
PATCH  /resources/{id}    Update
DELETE /resources/{id}    Delete

HTTP Status Codes

Testing Quick Reference

pytest

@pytest.fixture
def client():
    return TestClient(app)

def test_endpoint(client):
    response = client.get("/api/users")
    assert response.status_code == 200

vitest

import { describe, it, expect, vi } from 'vitest';

describe('Component', () => {
  it('should work', () => {
    expect(true).toBe(true);
  });
});

Docker Quick Reference

Multi-Stage Build

FROM node:20-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM node:20-alpine
COPY --from=builder /app/dist ./dist
USER node
CMD ["node", "dist/index.js"]

Compose

services:
  app:
    build: .
    ports:
      - "3000:3000"
    depends_on:
      db:
        condition: service_healthy
  db:
    image: postgres:16-alpine
    healthcheck:
      test: ["CMD", "pg_isready"]

CI/CD Quick Reference

GitHub Actions

name: CI
on: [push, pull_request]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
      - run: npm ci
      - run: npm test

TypeScript Quick Reference

Utility Types

Partial<T>      // All properties optional
Required<T>     // All properties required
Pick<T, K>      // Select properties
Omit<T, K>      // Exclude properties
Record<K, V>    // Object with key type K, value type V

Generics

function first<T>(arr: T[]): T | undefined {
  return arr[0];
}

Python Quick Reference

Async

async def fetch_data():
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as response:
            return await response.json()

Type Hints

def process(items: list[str]) -> dict[str, int]:
    return {item: len(item) for item in items}

React/Next.js Quick Reference

Server Component (default)

// app/page.tsx
async function Page() {
  const data = await fetch('...');
  return <div>{data}</div>;
}

Client Component

'use client';
import { useState } from 'react';

export function Counter() {
  const [count, setCount] = useState(0);
  return <button => setCount(c => c + 1)}>{count}</button>;
}