wireup.errors.WireupError: Cannot construct async objects fron a non-async context.

[almeynman]

Hello, I have created an async iterator for running transactions, here are the services involved:

pg_client.py

@service(lifetime=ServiceLifetime.TRANSIENT)
@dataclass
class PgClient:
    _pool: Pool

    @contextlib.asynccontextmanager
    async def run_transaction(self, connection: Connection | None = None) -> AsyncIterator[Connection]:
        if connection is not None:
            yield connection
            return
        async with self._pool.acquire() as conn, conn.transaction():
            yield conn


@service(lifetime=ServiceLifetime.SINGLETON)
async def create_pg_pool(env: Env) -> AsyncIterator[Pool]:
    # configure connection pool https://magicstack.github.io/asyncpg/current/usage.html#example-automatic-json-conversion
    user = env.POSTGRES_USER.get_secret_value()
    password = urllib.parse.quote_plus(env.POSTGRES_PASSWORD.get_secret_value())
    host = env.POSTGRES_HOST.get_secret_value()
    port = env.POSTGRES_PORT.get_secret_value()
    db_name = env.POSTGRES_DB_NAME.get_secret_value()

    dsn = f"postgresql://{user}:{password}@{host}:{port}/{db_name}"

    async def init(conn: Connection) -> None:
        await conn.set_type_codec("uuid", encoder=str, decoder=str, schema="pg_catalog")
        await register_vector(conn, schema="extensions")

    pool = await create_pool(dsn=dsn, init=init, min_size=5, max_size=20)
    yield pool
    await pool.close()

Then to instantiate in fastapi applicaiton I call container.warmup() in lifespan like so

def create_app() -> FastAPI:
    @asynccontextmanager
    async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
        container = app.state.container
        container.warmup()

        yield

        await container.aclose()

    app = FastAPI(lifespan=lifespan, debug=env.ENV != "production")

    container = create_container()
    app.state.container = container
    wireup.integration.fastapi.setup(app.state.container, app)

    return app

This throws wireup.errors.WireupError: Cannot construct async objects fron a non-async context. error

I managed to workaround it by awaiting for pg_client explicitly, like so

def create_app() -> FastAPI:
    @asynccontextmanager
    async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
        container = app.state.container

        # Fixes "wireup.errors.WireupError: Cannot construct async objects fron a non-async context."
        @container.autowire
        async def get_pg_client(pg_client: PgClient) -> PgClient:
            return pg_client

        await get_pg_client()
        container.warmup()

        yield

        await container.aclose()

    app = FastAPI(lifespan=lifespan, debug=env.ENV != "production")

    container = create_container()
    app.state.container = container
    wireup.integration.fastapi.setup(app.state.container, app)

    return app

However not sure if it's smth with the lib or I am just doing smth wrong

[maldoinc]

Hi, the issue is that warmup_container is a regular function and your create_pg_pool resource is an async one so it cannot be created from the warmup_container call. The fix you did works because the autowired get_pg_client is also async and as such wireup can await for pg pool.

#45 is precisely about this. To have an async verison of warmup_container use cases where underlying resources may be async factories. In your case I'd just remove the call to warmup_container and let the container create it when necessary.

[almeynman]

Cool, thanks. I will leave this workaround for now and will wait for the #45

[maldoinc]

Hi, with the new 0.16.0 version you can now just do await container.aget(PgClient).

from wireup.integration.fastapi import get_container

@asynccontextmanager
    async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
        container = get_container(app)
        await container.aget(PgClient)

        yield

        await container.aclose()