fastapi

# FastAPI Skill

Production-tested patterns for FastAPI with Pydantic v2, SQLAlchemy 2.0 async, and JWT authentication.

**Latest Versions** (verified January 2026):
- FastAPI: 0.128.0
- Pydantic: 2.11.7
- SQLAlchemy: 2.0.30
- Uvicorn: 0.35.0
- python-jose: 3.3.0

---

## Quick Start

### Project Setup with uv

```bash
# Create project
uv init my-api
cd my-api

# Add dependencies
uv add fastapi[standard] sqlalchemy[asyncio] aiosqlite python-jose[cryptography] passlib[bcrypt]

# Run development server
uv run fastapi dev src/main.py
```

### Minimal Working Example

```python
# src/main.py
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI(title="My API")

class Item(BaseModel):
    name: str
    price: float

@app.get("/")
async def root():
    return {"message": "Hello World"}

@app.post("/items")
async def create_item(item: Item):
    return item
```

Run: `uv run fastapi dev src/main.py`

Docs available at: `http://127.0.0.1:8000/docs`

---

## Project Structure (Domain-Based)

For maintainable projects, organize by domain not file type:

```
my-api/
├── pyproject.toml
├── src/
│   ├── __init__.py
│   ├── main.py              # FastAPI app initialization
│   ├── config.py            # Global settings
│   ├── database.py          # Database connection
│   │
│   ├── auth/                # Auth domain
│   │   ├── __init__.py
│   │   ├── router.py        # Auth endpoints
│   │   ├── schemas.py       # Pydantic models
│   │   ├── models.py        # SQLAlchemy models
│   │   ├── service.py       # Business logic
│   │   └── dependencies.py  # Auth dependencies
│   │
│   ├── items/               # Items domain
│   │   ├── __init__.py
│   │   ├── router.py
│   │   ├── schemas.py
│   │   ├── models.py
│   │   └── service.py
│   │
│   └── shared/              # Shared utilities
│       ├── __init__.py
│       └── exceptions.py
└── tests/
    └── test_main.py
```

---

## Core Patterns

### Pydantic Schemas (Validation)

```python
# src/items/schemas.p