rust - Rust提示我正在编写的方法存在生命周期

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This question already has answers here:

Lifetime error when creating a function that returns a value implementing serde::Deserialize

(2个答案)


在4个月前关闭。




我正在努力学习Rust的一生。因此，我在Web客户端包装中使用了以下方法。

pub async fn get_as_bytes<T: serde::Deserialize>(
    &self,
    url: &str,
    headers: Option<HeaderMap>,
) -> Result<T, Box<dyn Error>> {
    let mut req = self.reqwest_client.request(reqwest::Method::GET, url);

    if let Some(hds) = headers {
        req = req.headers(hds);
    }

    let resp: Response = req.send().await?;
    let full = resp.bytes().await?;

    let result = serde_json::from_slice(&full).unwrap();
    Ok(result)
}

当我尝试编译时，我得到了:

error[E0106]: missing lifetime specifier
  --> src/webclient.rs:53:41
   |
53 |     pub async fn get_as_bytes<T: serde::Deserialize>(&self, url: &str, headers: Option<HeaderMap>) -> Result<T, Box<dyn Error>> {
   |                                         ^^^^^^^^^^^ expected named lifetime parameter
   |
help: consider introducing a named lifetime parameter
   |
53 |     pub async fn get_as_bytes<'a, T: serde::Deserialize<'a>>(&self, url: &str, headers: Option<HeaderMap>) -> Result<T, Box<dyn Error>> {
   |                               ^^^           ^^^^^^^^^^^^^^^

error[E0597]: `full` does not live long enough
  --> src/webclient.rs:63:45
   |
63 |         let result = serde_json::from_slice(&full).unwrap();
   |                      -----------------------^^^^^-
   |                      |                      |
   |                      |                      borrowed value does not live long enough
   |                      argument requires that `full` is borrowed for `'static`
64 |         Ok(result)
65 |     }
   |     - `full` dropped here while still borrowed

自尝试返回 &full以来，我该如何使其最后使用？

最佳答案

只是作为将来的引用发布，而不删除问题。正如@Shepmaster在问题注释中提到的那样，que Lifetime error when creating a function that returns a value implementing serde::Deserialize解决了此问题。作为文档，代码将是:

pub async fn get_as_bytes<T: serde::de::DeserializeOwned >(&self, url: &str, headers: Option<HeaderMap>) -> Result<T, Box<dyn Error>> {
        let mut req = self.reqwest_client.request(reqwest::Method::GET, url);

        if let Some(hds) = headers {
            req = req.headers(hds);
        }

        let resp: Response = req.send().await?;
        let full = resp.bytes().await?;

        let result = serde_json::from_slice(&full).unwrap();
        Ok(result)
    }
    ```

关于rust - Rust提示我正在编写的方法存在生命周期，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/65011253/

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Answer 1

只是作为将来的引用发布，而不删除问题。正如@Shepmaster在问题注释中提到的那样，que Lifetime error when creating a function that returns a value implementing serde::Deserialize解决了此问题。作为文档，代码将是:

pub async fn get_as_bytes<T: serde::de::DeserializeOwned >(&self, url: &str, headers: Option<HeaderMap>) -> Result<T, Box<dyn Error>> {
        let mut req = self.reqwest_client.request(reqwest::Method::GET, url);

        if let Some(hds) = headers {
            req = req.headers(hds);
        }

        let resp: Response = req.send().await?;
        let full = resp.bytes().await?;

        let result = serde_json::from_slice(&full).unwrap();
        Ok(result)
    }
    ```