Feature Request: Support for async closures

[ProbstDJakob]

Motivation

Since AsyncFn and therefore async closures have been stabilised in rust version 1.85.0 a few months back, are there any plans to support this for example in transactions?

Proposed Solutions

For example the arguments to the transaction functions can be changed to instead receive impl AsyncFnOnce() -> Result<T, E> or if this is to late for version 2.0.0, another pair of transaction functions can be added which receive the async closure.

[negezor]

I write a lot of transactions in my backend, it would be nice to improve the ergonomics in the 2.0.0 version of Sea-Orm

[tyt2y3]

@negezor can you give some more examples to the API and the usage?

[negezor]

@tyt2y3 as @ProbstDJakob mentioned, the only change here is that we get rid of the extra level of nesting, and this code becomes simpler to write

Before:

db.transaction::<_, _, DbErr>(|txn| {
        Box::pin(async move {
            cake::Entity::insert(cake::ActiveModel {
                name: Set("Chocolate".to_owned()),
                price: Set(3.into()),
                bakery_id: Set(Some(1)),
                gluten_free: Set(true),
                ..Default::default()
            })
            .exec(txn)
            .await?;

            Ok(())
        })
    })
    .await
    .expect("insert succeeds");

After:

db.transaction::<_, _, DbErr>(async |txn| {
        cake::Entity::insert(cake::ActiveModel {
            name: Set("Chocolate".to_owned()),
            price: Set(3.into()),
            bakery_id: Set(Some(1)),
            gluten_free: Set(true),
            ..Default::default()
        })
        .exec(txn)
        .await?;

        Ok(())
    })
    .await
    .expect("insert succeeds");

If I’m not mistaken, this is already possible now. This would be more than enough for the current moment. I recently saw a blog post about sea-orm-sync. This would also improve the overall developer experience - the only difference would be the async keyword in front of the closure.

[ProbstDJakob]

Furthermore one can use references in the block. Currently this will result in a xyz does not live long enough. With AsyncFn this will be fixed. For example: https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=5548c30931deb5b21d826a0edc54e26e

[Huliiiiii]

rust-lang/rust#146790

I'm running into some issues — it seems there's currently no way to mark the Futures of async functions as Send.
Any help would be appreciated.

[landonpoch]

I hope this: #3053 can get adopted in to the release candidate on time. It should resolve this issue.

[landonpoch]

Seems like we need to wait for this to stabilize first: rust-lang/rust#109417