How to use async/await in iter map?

[lz1998]

    let ids = vec![1, 2, 3];
    let data = ids
        .into_iter()
        .map(|x| async {
            // httpGetData(id).await
        })
        .collect();

[Darksonn]

The way to do this is to use a Stream rather than an Iterator. Streams have a method similar to map called then which lets you perform async operations.

use futures::stream::StreamExt;

async fn http_get_data(id: i32) -> String {
    id.to_string()
}

#[tokio::main]
async fn main() {
    let ids = vec![1, 2, 3];
    let data: Vec<_> = futures::stream::iter(ids)
        .then(|id| async move {
            http_get_data(id).await
        })
        .collect()
        .await;

    println!("{:?}", data);
}

Note that the async block is not actually necessary in this particular example:

let data: Vec<_> = futures::stream::iter(ids)
    .then(|id| http_get_data(id))
    .collect()
    .await;

[lz1998]

The way to do this is to use a Stream rather than an Iterator. Streams have a method similar to map called then which lets you perform async operations.

use futures::stream::StreamExt;

async fn http_get_data(id: i32) -> String {
    id.to_string()
}

#[tokio::main]
async fn main() {
    let ids = vec![1, 2, 3];
    let data: Vec<_> = futures::stream::iter(ids)
        .then(|id| async move {
            http_get_data(id).await
        })
        .collect()
        .await;

    println!("{:?}", data);
}

Note that the async block is not actually necessary in this particular example:

let data: Vec<_> = futures::stream::iter(ids)
    .then(|id| http_get_data(id))
    .collect()
    .await;

Then how to execute requests at the same time with a concurrent limit?

[Darksonn]

Check out this blog post for that.