我想用下面的方法初始化类的时候组织一个连接池
import asyncio
import asyncpg
class DBCommands:
def __init__(self, uri: str) -> None:
loop = asyncio.get_event_loop()
self.pool: asyncpg.pool.Pool = loop.run_until_complete(asyncpg.create_pool(dsn=uri))
async def get_id_admins(self) -> list:
async with self.pool.acquire():
result = await self.pool.fetch("SELECT chat_id FROM users WHERE role_user = 'admin'")
admins_id = [row[0] for row in result]
return admins_id
由于池应该是一个,使用上述实现,这是行不通的。我决定使用单例,但我不明白如何实现它。下面是我想出的版本。告诉我如何最好地解决这个问题。此外,我不明白如何最好以及在哪里关闭连接。我是使用模式的新手,刚刚开始学习 OOP。
import asyncio
import asyncpg
class Singleton(type):
_instances = {}
def __call__(cls, *args, **kwargs):
if cls not in cls._instances:
cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
return cls._instances[cls]
class DBManager(metaclass=Singleton):
@classmethod
def connect(cls, uri):
loop = asyncio.get_event_loop()
return loop.run_until_complete(asyncpg.create_pool(dsn=uri))
class DBCommands:
def __init__(self, uri) -> None:
self.uri = uri
self.pool = DBManager.connect(uri)
async def get_id_admins(self) -> list:
async with self.pool.acquire():
result = await self.pool.fetch("SELECT chat_id FROM users WHERE role_user = 'admin'")
admins_id = [row[0] for row in result]
return admins_id
我假设可以将打开和关闭池添加到__aenter__
和 __aexit__