如何在FastAPI中实现持久的数据库连接？

from fastapi import Depends, FastAPI
import asyncpg

app = FastAPI()

# 创建数据库连接池
async def create_db_pool():
    pool = await asyncpg.create_pool(
        host="localhost",
        port=5432,
        user="myuser",
        password="mypassword",
        database="mydatabase"
    )
    return pool

# 定义数据库连接的依赖项
async def get_db_pool():
    pool = await create_db_pool()
    try:
        yield pool
    finally:
        await pool.close()

# 定义数据库模型
class User:
    def __init__(self, id: int, name: str):
        self.id = id
        self.name = name

# 路由函数中使用数据库连接
@app.get("/users/{user_id}")
async def get_user(user_id: int, db: asyncpg.Pool = Depends(get_db_pool)):
    query = "SELECT id, name FROM users WHERE id = $1"
    row = await db.fetchrow(query, user_id)
    if row:
        user = User(row["id"], row["name"])
        return {"user": user}
    else:
        return {"message": "User not found"}