How to use r2d2 with diesel_async?

[Abdillah]

How to use r2d2 with diesel_async? As I saw the feature here.

I do this but found an error on below.

let db_factory = std::thread::spawn(|| {
    let mut rt = tokio::runtime::Runtime::new().unwrap();
    let local = tokio::task::LocalSet::new();
    let url = dotenv::var("DB_CONNSTR").unwrap();
    local.block_on(&mut rt, establish_connection(&url)).unwrap()
});
println!("Creating database connection..");
let db = diesel_async::pooled_connection::AsyncDieselConnectionManager::new(
    db_factory.join().expect("Thread db_factory panicked"),
);
let pool = diesel::r2d2::Pool::builder()
    .max_size(15)
    .build(db)
    .unwrap();

error[E0277]: the trait bound `AsyncDieselConnectionManager<AsyncPgConnection>: ManageConnection` is not satisfied
   --> src/main.rs:65:9
    |
65  | /         diesel::r2d2::Pool<
66  | |             diesel_async::pooled_connection::AsyncDieselConnectionManager<AsyncPgConnection>,
67  | |         >,
    | |_________^ the trait `ManageConnection` is not implemented for `AsyncDieselConnectionManager<AsyncPgConnection>`
    |

[weiznich]

It's not supported to use r2d2 directly with any AsyncConnection type provided by diesel-async, as using an sync connection pool with an async connection is an anti-pattern. You either want to use an async-connection pool (like bb8, deadpool or mobc) with an async connection type or you want to use a sync connection pool (like r2d2) with a sync connection type (like diesel::PgConnection, or diesel_async::async_connection_wrapper::AsyncConnectionWrapper<diesel_async::AsyncPgConnection>)

[Abdillah]

Ah, okay thanks..
I tried to implement it myself, but turns out I need to impl diesel::Connection to AsyncPgConnection which is not possible due to conflicting methods.

[weiznich]

You might want to use diesel_async::async_connection_wrapper::AsyncConnectionWrapper<diesel_async::AsyncPgConnection> in that case. It provides such an implementation.