how to optimize the multi unwrap code statement in rust

Question

I am learning to use rust v1.65.0 to send a http request. Now I have a rust code block like this:

pub async fn get_queue_cv() {
    let client = Client::new();
    let url_path = "/cv/gen/v1/list";
    let url = format!("{}{}", get_app_config("cv.cv_api_url"), url_path);
    let response = client
        .post(url)
        .headers(construct_headers())
        .body("{}")
        .send()
        .await;
    match response {
        Ok(r) => {
            let r: serde_json::Value = r.json().await.unwrap();
            match r.get("result") {
                Some(_) => {},
                None => {},
            }
            let result: &serde_json::Value = r.get("result").unwrap();
            let first_element = result.get(0).unwrap();
            let queue_record: CvGen = serde_json::from_value(first_element.clone()).unwrap();
            let tpl_resp = get_template(queue_record);
            tpl_resp.await;
        }
        Err(e) => println!("Error: {}", e),
    }
}

This code works fine, but sometimes when the server return null results, the unwrap will going o panic. Now I want to handle the unwrap failed situation, I am tried to use match, but now I found using match make the code has too much nested level and maket the code ugly. what I want just simplely return if any of unwrap failed. I have tried unwrap_or_else but I di d not know how to define the else condition. what should I do to handle this unwrap with a better way?

Maybe try with `if let` statement, regarding the case it can be enough and you avoid too much nesting. — Peterrabbit, May 27 '23 at 17:40

score 1 · Accepted Answer · edited May 28 '23 at 08:13

You can try a "Maybe" monad approach via following methods of an Option:

let responce = r.get("result")
  .map(|x| x.get(0))
  .map(|x| serde_json::from_value(x.clone()))
  .map(|x| get_template(x));
match responce {
  Some(awaiter) => awaiter.await
  None => // TODO: your implementation
}

how to optimize the multi unwrap code statement in rust

1 Answers1