Struct Debug

pub struct Debug<E>(pub E);

Debug prints the internal value before forwarding to the 500 error catcher.

This value exists primarily to allow handler return types that would not otherwise implement Responder. It is typically used in conjunction with Result<T, E> where E implements Debug but not Responder.

Note that because of it’s common use as an error value, std::io::Error does implement Responder. As a result, a std::io::Result<T> can be returned directly without the need for Debug:

use std::io;

use rocket::fs::NamedFile;

#[get("/")]
async fn index() -> io::Result<NamedFile> {
    NamedFile::open("index.html").await
}

Example

Because of the generic From<E> implementation for Debug<E>, conversions from Result<T, E> to Result<T, Debug<E>> through ? occur automatically:

use std::string::FromUtf8Error;

use rocket::response::Debug;

#[get("/")]
fn rand_str() -> Result<String, Debug<FromUtf8Error>> {
    let bytes: Vec<u8> = random_bytes();
    Ok(String::from_utf8(bytes)?)
}

It is also possible to map the error directly to Debug via Result::map_err():

use std::string::FromUtf8Error;

use rocket::response::Debug;

#[get("/")]
fn rand_str() -> Result<String, Debug<FromUtf8Error>> {
    let bytes: Vec<u8> = random_bytes();
    String::from_utf8(bytes).map_err(Debug)
}

Tuple Fields

0: E

Trait Implementations

impl<E: Debug> Debug for Debug<E>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<E> From<E> for Debug<E>

fn from(e: E) -> Self

Converts to this type from the input type.

impl<'r, E: Debug> Responder<'r, 'static> for Debug<E>

fn respond_to(self, _: &'r Request<'_>) -> Result<'static>

Returns Ok if a Response could be generated successfully. Otherwise, returns an Err with a failing Status.

impl<T> Sentinel for Debug<T>

A sentinel that never aborts. The Responder impl for Debug will never be called, so it’s okay to not abort for failing T: Sentinel.

fn abort(_: &Rocket<Ignite>) -> bool

Returns true if launch should be aborted and false otherwise.