How to use axum::extract::State with #[oasgen] in handlers?

[tgrushka]

I am using handlers that automatically extract state with less boilerplate like this:

pub type Tx = axum_sqlx_tx::Tx<sqlx::Postgres>;

pub type TxState = axum_sqlx_tx::State<sqlx::Postgres>;

#[derive(Clone)]
pub struct ApiState {
    pub config: Config,
    pub tx: TxState,
    pub redis: Redis,
}

pub fn jobs_routes() -> Router<ApiState> {
    Router::new()
...
        .route("/checkout", patch(checkout_job))
...
}

#[oasgen]
pub async fn checkout_job(mut tx: Tx, config: Config) -> ApiResult<CheckoutJobResponse> {
...
}

But I can't use oasgen with this, because it thinks tx and config should be params, when they are internal axum state extractors and should definitely not be API params.

Errors:

the trait bound `axum_sqlx_tx::Tx<Postgres>: OaParameter` is not satisfied...
the trait bound `config::Config: OaParameter` is not satisfied...

Is there a workaround? I think a lot of people use axum this way. I even tried wrapping in State<T> like this:

#[oasgen]
pub async fn checkout_job(
    State(mut tx): State<Tx>,
    State(config): State<Config>,
) -> ApiResult<CheckoutJobResponse> {
...
}

Which is still too much boilerplate for me anyway, but still get errors:

the trait bound `axum::extract::State<axum_sqlx_tx::Tx<Postgres>>: OaParameter` is not satisfied
...
the trait bound `axum::extract::State<config::Config>: OaParameter` is not satisfied

Obviously OaParameter can't be implemented for external crates, and I wouldn't want to, anyway, as these are internal and should never be exposed to the API.

I was looking at this crate as a possible alternative to utoipa because it has a lot of boilerplate and this seems more automatic. Is there any way oasgen could allow configuration or detection of my ApiState or the state of the handlers or something and ignore those parameters entirely?

Thanks!

[kurtbuilds]

Thank you for the great writeup.

You can have empty implementations of OaParameter for state objects. Check out core/src/schema/axum.rs, where there's:

impl<T> OaParameter for axum::extract::State<T> {}

Do you have multiple versions of a library (axum 7 vs 8, for example?). There are trait restrictions on the generic in the above implentation, so your second code snippit should not be throwing the errors you're sharing.

To get the first code snippit working, the Tx and Config objects need to implement OaParamater (presumably an empty implementation). axum_sqlx_tx seems like an extremely small library, so I have some preference for the implementation to live in that crate instead of oasgen directly, but open to discussion on it.