请求、响应与错误

pub trait FromRequest: Sized {
    fn from_request(cx: &Cx, body: Body) -> impl Future<Output = Result<Self>> + Send;
}

### curl -X POST -d {"name":"a","age":3} http://127.0.0.1:38111/users
HTTP/1.1 400 Bad Request
content-type: text/plain; charset=utf-8
vary: accept-encoding
content-length: 67

bad request: expected request with `Content-Type: application/json`

### curl -X POST -H Content-Type: application/json -d {"name":"a","age":300} http://127.0.0.1:38111/users
HTTP/1.1 400 Bad Request
content-type: text/plain; charset=utf-8
vary: accept-encoding
content-length: 105

bad request: invalid JSON value: invalid value: integer `300`, expected u8 at line 1 column 21 (at `age`)

### curl -X POST -H Content-Type: application/json -d {"name":"a" http://127.0.0.1:38111/users
HTTP/1.1 400 Bad Request
content-type: text/plain; charset=utf-8
vary: accept-encoding
content-length: 90

bad request: invalid JSON syntax: EOF while parsing an object at line 1 column 11 (at `?`)

pub trait IntoResponse {
    fn into_response(self, cx: &Cx) -> Result<Response>;
}

#[route(GET "./users/find")]
async fn find() -> Result<&'static str> {
  let found: Option<&'static str> = None;
  Ok(found.ok_or_not_found()?)
}

#[route(POST "./login")]
async fn login() -> Result<SeeOther> {
  Ok(see_other("/dashboard"))
}

### curl http://127.0.0.1:38111/users/find
HTTP/1.1 404 Not Found
content-type: text/plain; charset=utf-8
content-length: 9

not found

### curl -X POST http://127.0.0.1:38111/login
HTTP/1.1 303 See Other
location: /dashboard
content-length: 0

fn error_into_response(cx: &Cx, error: Error) -> Response {
    macro_rules! try_downcast {
        ($ident:ident as $ty:ty) => {
            match $ident.downcast_cloned::<$ty>() {
                Ok(error) => return into_response_or_500(cx, error),
                Err(error) => error,
            }
        };
    }
    let error = try_downcast!(error as ForbiddenError);
    let error = try_downcast!(error as BadRequestError);
    // ...
    let error = try_downcast!(error as TooManyRequestsError);

    into_response_or_500(cx, internal_server_error(error))
}

pub struct InternalServerError {
    _inner: Error,
}

Poll::Ready(Err(error)) => {
    *this.done = true;
    // The response committed with the first content, so a
    // redirect can no longer change the status line; it degrades
    // to a client-side navigation instead.
    match redirect_location(error) {
        Ok(location) => {
            let chunk = this.delivery.redirect(&location);
            Poll::Ready(Some(Ok(Frame::data(chunk.into()))))
        }
        Err(error) => Poll::Ready(Some(Err(error.into()))),
    }
}

#[page("./before")]
async fn before() -> Result<impl View> {
  Err::<(), _>(redirect("/login"))?;
  Ok(view! { <p>"never"</p> })
}

#[component]
async fn guard() -> Result<impl View> {
  tokio::time::sleep(Duration::from_millis(200)).await;
  Err::<(), _>(redirect("/login?next=\"x\""))?;
  Ok(view! { <p>"secret"</p> })
}

[    5ms] read 128 bytes:
HTTP/1.1 307 Temporary Redirect
location: /login
connection: close
content-length: 0

[    0ms] read 389 bytes:
HTTP/1.1 200 OK
content-type: text/html; charset=utf-8
...
<!DOCTYPE html><html><body><p>first screen</p><!--::topcoat::region::start(d139fe525a3cb181f54fb3f0ffe4eda4)--><p>checking</p><!--::topcoat::region::end(d139fe525a3cb181f54fb3f0ffe4eda4)--></body></html>

[  203ms] read 72 bytes:
3D
<script>window.location.replace("/login?next=\"x\"")</script>
0

[    5ms] read 389 bytes:
HTTP/1.1 200 OK
...
transfer-encoding: chunked

CB
<!DOCTYPE html><html><body><p>first screen</p><!--::topcoat::region::start(563fb7caab8260bea62e209677945068)--><p>checking</p><!--::topcoat::region::end(563fb7caab8260bea62e209677945068)--></body></html>

[  207ms] <EOF>