@dataclass
class NoResultError(Exception):
    """No results were returned from the last line of a query."""
    query: str = None
@dataclass
class Resource:
    # SNIP
    async def store(self):
        """Stores the object in the database."""
        global connection
        log.debug("Storing %s", self)
        if old := await get(self.__class__, self.id):
            old_ser = ser(old)
            differences = {k: v for k, v in ser(self).items() if v != old_ser[k]}
            record = await connection.update(self.id, data=differences)
            log.debug("Updated %s", record)
        else:
            record = await connection.create(self.id, data=ser(self))
            log.debug("Inserted %s", record)
async def asetup():
    """Connects and authenticates with the local database."""
    global connection
    log.info("Setting up SurrealDB database...")
    connection = Surreal("ws://localhost:8000/rpc")
    await connection.connect()
    await connection.signin({"user": secrets['db_username'], "pass": secrets['db_password']})
    await connection.use("foo", "bar")
    log.info("Database setup complete!")
def setup():
    t = asyncio.get_event_loop().run_until_complete(asetup())
async def ateardown():
    global connection
    log.info("Closing SurrealDB database...")
    await connection.close()
    log.info("Database closed!")
def teardown(bot: discord.Bot):
    t = asyncio.get_event_loop().run_until_complete(ateardown())
# SNIP
async def get(obj_type: type[R], obj_id: str) -> R:
    global connection
    assert (
        obj_type.__name__ == obj_id.split(":")[0]
    ), "That object ID does not match the expected type."
    log.debug("Getting %s", obj_id)
    obj = deser(obj_type, await connection.select(obj_id))
    log.debug("Found %s", obj)
    return obj
async def run_query(obj_type: type[R], query: str, **params) -> list[R]:
    """Runs a query against the database, and returns the results from the last line.
    Args:
        obj_type (Type[R]): The object type to expect.
        query (str): The query to run.
        **params: Parameters to use in the query.
    Returns:
        list[R]: A list of objects returned from the last line of the query.
    Raises:
        NoResultError: No results or an error was returned from the last line.
    """
    global connection
    log.debug("Running query %s with params %s", query, params)
    try:
        results = (await connection.query(query, params))[-1]["result"]
    except (IndexError, KeyError) as e:
        raise NoResultError(query) from e
    else:
        log.debug("Found %s", results)
        return deser(list, results)

...in run_query
results = (await connection.query(query, params))[-1]["result"]
^^^^^^^^^^
NameError: name 'connection' is not defined

class DatabaseConnection:
def __init__(self):
self.connection = None
async def asetup(self):
log.info("Setting up SurrealDB database...")
self.connection = Surreal("ws://localhost:8000/rpc")
await self.connection.connect()
await self.connection.signin({"user": secrets['db_username'], "pass": secrets['db_password']})
await self.connection.use("foo", "bar")
log.info("Database setup complete!")
async def ateardown(self):
log.info("Closing SurrealDB database...")
await self.connection.close()
log.info("Database closed!")
async def get(self, obj_type: type[R], obj_id: str) -> R:
log.debug("Getting %s", obj_id)
obj = deser(obj_type, await self.connection.select(obj_id))
log.debug("Found %s", obj)
return obj
async def run_query(self, obj_type: type[R], query: str, **params) -> list[R]:
log.debug("Running query %s with params %s", query, params)
try:
results = (await self.connection.query(query, params))[-1]["result"]
except (IndexError, KeyError) as e:
raise NoResultError(query) from e
else:
log.debug("Found %s", results)
return deser(list, results)
# Usage
db = DatabaseConnection()
await db.asetup()
results = await db.run_query(obj_type, query, **params)
await db.ateardown()