如何在FastAPI中实现数据库连接和事务处理

pip install sqlalchemy
pip install mysql-connector-python

from fastapi import Depends, FastAPI
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm.session import Session

app = FastAPI()

SQLALCHEMY_DATABASE_URL = "mysql+mysqlconnector://user:password@localhost/db_name"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL,
    pool_size=10,
    max_overflow=20
)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

async def get_db() -> Session:
    try:
        db = SessionLocal()
        yield db
    finally:
        db.close()

from fastapi import Depends, FastAPI
from sqlalchemy.orm import Session
from .models import User
from .crud import create_user
from .database import get_db

app = FastAPI()

@app.post("/users/")
async def create_user_handler(user: User, db: Session = Depends(get_db)):
    return create_user(db=db, user=user)

from sqlalchemy.orm import Session
from .models import User

def create_user(db: Session, user: User):
    try:
        db.begin()
        db.add(user)
        db.commit()
        db.refresh(user)
        return user
    except:
        db.rollback()
        raise