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Use when building high-performance async Python APIs with FastAPI and Pydantic V2. Invoke to create REST endpoints, define Pydantic models, implement authentication flows, set up async SQLAlchemy data
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Paste the copied command in a terminal. It installs this SKILL.md into that agent.
npx skills add Jeffallan/claude-skills --skill fastapi-expert -a cursor -y
Use when building high-performance async Python APIs with FastAPI and Pydantic V2. Invoke to create REST endpoints, define Pydantic models, implement authentication flows, set up async SQLAlchemy database operations, add JWT authentication, build WebSocket endpoints, or generate OpenAPI documentation. Trigger terms: FastAPI, Pydantic, async Python, Python API, REST API Python, SQLAlchemy async, JWT authentication, OpenAPI, Swagger Python.
Use when building high-performance async Python APIs with FastAPI and Pydantic V2. Invoke to create REST endpoints, define Pydantic models, implement authentication flows, set up async SQLAlchemy database operations, add JWT authentication, build WebSocket endpoints, or generate OpenAPI documentation. Trigger terms: FastAPI, Pydantic, async Python, Python API, REST API Python, SQLAlchemy async, JWT authentication, OpenAPI, Swagger Python.
Deep expertise in async Python, Pydantic V2, and production-grade API development with FastAPI.
pytest after each endpoint group and verify OpenAPI docs at /docsCheckpoint after each step: confirm schemas validate correctly, endpoints return expected HTTP status codes, and
/docsreflects the intended API surface before proceeding.
Schema + endpoint + dependency injection in one cohesive unit:
# schemas.py
from pydantic import BaseModel, EmailStr, field_validator, model_config
class UserCreate(BaseModel):
model_config = model_config(str_strip_whitespace=True)
email: EmailStr
password: str
name: str | None = None
@field_validator("password")
@classmethod
def password_strength(cls, v: str) -> str:
if len(v) < 8:
raise ValueError("Password must be at least 8 characters")
return v
class UserResponse(BaseModel):
model_config = model_config(from_attributes=True)
id: int
email: EmailStr
name: str | None = None
# routers/users.py
from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.ext.asyncio import AsyncSession
from typing import Annotated
from app.database import get_db
from app.schemas import UserCreate, UserResponse
from app import crud
router = APIRouter(prefix="/users", tags=["users"])
DbDep = Annotated[AsyncSession, Depends(get_db)]
@router.post("/", response_model=UserResponse, status_code=status.HTTP_201_CREATED)
async def create_user(payload: UserCreate, db: DbDep) -> UserResponse:
existing = await crud.get_user_by_email(db, payload.email)
if existing:
raise HTTPException(status_code=status.HTTP_409_CONFLICT, detail="Email already registered")
return await crud.create_user(db, payload)
# crud.py
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from app.models import User
from app.schemas import UserCreate
from app.security import hash_password
async def get_user_by_email(db: AsyncSession, email: str) -> User | None:
result = await db.execute(select(User).where(User.email == email))
return result.scalar_one_or_none()
async def create_user(db: AsyncSession, payload: UserCreate) -> User:
user = User(email=payload.email, hashed_password=hash_password(payload.password), name=payload.name)
db.add(user)
await db.commit()
await db.refresh(user)
return user
# security.py
from datetime import datetime, timedelta, timezone
from jose import JWTError, jwt
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from typing import Annotated
SECRET_KEY = "<jwt-secret>" # use os.environ / settings
ALGORITHM = "HS256"
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/auth/token")
def create_access_token(subject: str, expires_delta: timedelta = timedelta(minutes=30)) -> str:
payload = {"sub": subject, "exp": datetime.now(timezone.utc) + expires_delta}
return jwt.encode(payload, SECRET_KEY, algorithm=ALGORITHM)
async def get_current_user(token: Annotated[str, Depends(oauth2_scheme)]) -> str:
try:
data = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
subject: str | None = data.get("sub")
if subject is None:
raise ValueError
return subject
except (JWTError, ValueError):
raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid credentials")
CurrentUser = Annotated[str, Depends(get_current_user)]
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Pydantic V2 | references/pydantic-v2.md | Creating schemas, validation, model_config |
| SQLAlchemy | references/async-sqlalchemy.md | Async database, models, CRUD operations |
| Endpoints | references/endpoints-routing.md | APIRouter, dependencies, routing |
| Authentication | references/authentication.md | JWT, OAuth2, get_current_user |
| Testing | references/testing-async.md | pytest-asyncio, httpx, fixtures |
| Django Migration | references/migration-from-django.md | Migrating from Django/DRF to FastAPI |
field_validator, model_validator, model_config)Annotated pattern for dependency injectionX | None instead of Optional[X]@validator, class Config)When implementing FastAPI features, provide:
FastAPI, Pydantic V2, async SQLAlchemy, Alembic migrations, JWT/OAuth2, pytest-asyncio, httpx, BackgroundTasks, WebSockets, dependency injection, OpenAPI/Swagger
Maintained by @jeffallan, Principal Consultant at Synergetic Solutions