Copilot-Skills fastapi.instructions.md

FastAPI Instructions

Auto-loaded when: Working with files matching: **/*.py, **/main.py, **/fastapi*

Default Behaviors

When working with FastAPI:

1. Follow Official Patterns: Use patterns from official FastAPI documentation
2. Type Hints: Always use Pydantic models for request/response bodies
3. Error Handling: Implement proper exception handlers with HTTPException
4. Async/Await: Use async routes for I/O operations
5. Validation: Leverage Pydantic for automatic validation
6. Documentation: Use docstrings for all route functions
7. Status Codes: Return appropriate HTTP status codes

Common Workflows

Basic API Endpoint

from fastapi import FastAPI, HTTPException
from pydantic import BaseModel

app = FastAPI()

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

@app.get("/items/{item_id}")
async def get_item(item_id: int):
    return {"item_id": item_id}

@app.post("/items/", status_code=201)
async def create_item(item: Item):
    return item

With Database (Prisma/SQLAlchemy)

from prisma import Prisma
from contextlib import asynccontextmanager

db = Prisma()

@asynccontextmanager
async def lifespan(app: FastAPI):
    await db.connect()
    yield
    await db.disconnect()

app = FastAPI(lifespan=lifespan)

@app.get("/users/{user_id}")
async def get_user(user_id: int):
    return await db.user.find_unique(where={"id": user_id})

With Claude/OpenAI Integration

import anthropic
from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()
client = anthropic.Anthropic()

class Message(BaseModel):
    content: str

@app.post("/analyze")
async def analyze(msg: Message):
    response = client.messages.create(
        model="claude-3-sonnet-20250219",
        max_tokens=1024,
        messages=[{"role": "user", "content": msg.content}]
    )
    return {"analysis": response.content[0].text}

Dependency Injection

from fastapi import Depends, FastAPI

async def get_query(q: str | None = None):
    return q

@app.get("/search")
async def search(q: str = Depends(get_query)):
    return {"q": q}