Rust collect() 具有两个以上元素的元组

Question

我很难收集包含这三个元素的元组：

let create_task = |msg| {
    // We need to keep the message_id to report failures to SQS
    // and the receipt_handle to delete the processed messages from SQS.
    let SqsMessageObj {
        message_id,
        body,
        receipt_handle,
        ..
    } = msg;

    let span = tracing::span!(tracing::Level::INFO, "Handling SQS msg", message_id);
    let task = async {
        let item = serde_json::from_value(body)?;
        f(item, app_config).await
    };

    (
        message_id.unwrap_or_default(),
        receipt_handle.unwrap_or_default(),
        task,
    )
};

print!("{:?}", event.payload);

let (ids, receipts, tasks) = event.payload.records.into_iter().map(create_task).collect();

这是基于使用 Rust lambda 进行高级 SQS 批处理的 AWS-labs 示例代码。

我已经尝试过this thread的解决方案，但似乎我得到了一个嵌套的元组。有什么线索吗？

Answer 1

您可以将

unzip()

与嵌套元组一起使用：

let create_task = |msg| {
    // We need to keep the message_id to report failures to SQS
    let SqsMessageObj {
        message_id,
        body,
        message_attributes,
        receipt_handle,
        ..
    } = msg;

    let span = tracing::span!(tracing::Level::INFO, "Handling SQS msg", message_id);
    let task = async {
        let item = serde_json::from_value(body)?;
        f(item, app_config).await
    };

    (
        (
            message_id.unwrap_or_default(),
            receipt_handle.unwrap_or_default(),
        ),
        task,
    )
};

print!("{:?}", event.payload);

let ((ids, receipts), tasks) = event.payload.records.into_iter().map(create_task).unzip();