# Python Fastapi

> Build high-performance APIs using FastAPI framework with Python type hints.

- Skill: `heldinhow/python-fastapi` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add heldinhow/python-fastapi`
- Raw SKILL.md: https://api.skillmd.com/api/skills/heldinhow/python-fastapi/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: Heldinhow (https://skillmd.com/u/heldinhow)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/heldinhow/python-fastapi

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# Python FastAPI

## Overview
FastAPI is a modern Python web framework for building APIs with automatic documentation. This skill should be invoked when building high-performance APIs that benefit from Python's type hints and FastAPI's automatic validation.

## Core Principles
- **Type Hints**: Leverage Python type hints for validation
- **Automatic Docs**: OpenAPI/Swagger generated automatically
- **Async Support**: Native async/await support
- **Dependency Injection**: Use Depends for clean code

## Preparation Checklist
- [ ] Install FastAPI: `pip install fastapi`
- [ ] Choose ASGI server (Uvicorn, Hypercorn)
- [ ] Plan API structure
- [ ] Define Pydantic models

## Step-by-Step Process
1. **Install**: Add FastAPI and uvicorn
2. **Define Models**: Create Pydantic models
3. **Routes**: Add route handlers
4. **Validate**: Use type hints and Pydantic
5. **Document**: Access automatic docs at /docs
6. **Run**: Start with uvicorn

## Do's and Don'ts
- ✅ **Do** use Pydantic for validation
- ✅ **Do** leverage async for I/O operations
- ✅ **Do** use dependency injection
- ❌ **Don't** ignore type hints
- ❌ **Don't** skip error handling
- ❌ **Don't** use sync code for DB calls

## Anti-Patterns
- **No Validation**: Skipping Pydantic models
- **Sync DB**: Using synchronous database calls
- **Missing Errors**: Not handling HTTP exceptions
- **No Docs**: Not reviewing automatic docs