correct approach to passing R2D2 database pool to each request?

[catsharkdigital]

Somewhat new to rust and very new to poem, some experience with Axum where a database pool would be passed using an extractor. What's the preferred approach to introducing a database pool to each request? Would it be done with a custom Middleware layer or would another approach be more appropriate?

Thanks!

[sunli829]

I recommend using Data<T>, in fact this is very similar to Axum.

poem/examples/openapi/todos/src/main.rs

Line 159 in a252560

.data(pool);

[catsharkdigital]

Thank you sunli829 , I was able to get a minimal example working. Posting my example here in case anyone else finds it helpful.

struct Api;

#[OpenApi]
impl Api {
    //#[handler]
    #[oai(path = "/hello", method = "get")]
    async fn index(&self,
                   db_pool: Data<&MysqlPool>,
                   name: Query<Option<String>>) -> PlainText<String> {

        let mut conn = db_pool.get().unwrap();
        let users = User::get_all(&mut conn).unwrap();

        match name.0 {
            Some(name) => PlainText(format!("hello, {}!, Retrieved {} Users", name, users.len())),
            None => PlainText("hello!".to_string()),
        }

    }
}

#[tokio::main]
async fn main() -> Result<(), std::io::Error> {

    //let shared_db_pool = Arc::new(establish_connection);
    let shared_db_pool: MysqlPool = establish_connection();

    let api_service =
        OpenApiService::new(Api, "Hello World", "1.0").server("http://localhost:3000/api");
    let ui = api_service.swagger_ui();
    let app = Route::new()
        .nest("/api", api_service.data(shared_db_pool))
        .nest("/", ui);

    poem::Server::new(TcpListener::bind("127.0.0.1:3000"))
        .run(app)
        .await
}