Struct Error

pub struct Error { /* private fields */ }

An error that occurs during launch.

An Error is returned by launch() when launching an application fails or, more rarely, when the runtime fails after launching.

Panics

A value of this type panics if it is dropped without first being inspected. An inspection occurs when any method is called. For instance, if println!("Error: {}", e) is called, where e: Error, the Display::fmt method being called by println! results in e being marked as inspected; a subsequent drop of the value will not result in a panic. The following snippet illustrates this:

if let Err(error) = rocket::build().launch().await {
    // This println "inspects" the error.
    println!("Launch failed! Error: {}", error);

    // This call to drop (explicit here for demonstration) will do nothing.
    drop(error);
}

When a value of this type panics, the corresponding error message is pretty printed to the console. The following illustrates this:

let error = rocket::build().launch().await;

// This call to drop (explicit here for demonstration) will result in
// `error` being pretty-printed to the console along with a `panic!`.
drop(error);

Usage

An Error value should usually be allowed to drop without inspection. There are at least two exceptions:

1. If you are writing a library or high-level application on-top of Rocket, you likely want to inspect the value before it drops to avoid a Rocket-specific panic!. This typically means simply printing the value.

2. You want to display your own error messages.

Implementations

impl Error

pub fn kind(&self) -> &ErrorKind

Retrieve the kind of the launch error.

Example

use rocket::error::ErrorKind;

if let Err(error) = rocket::build().launch().await {
    match error.kind() {
        ErrorKind::Io(e) => println!("found an i/o launch error: {}", e),
        e => println!("something else happened: {}", e)
    }
}

pub fn pretty_print(&self) -> &'static str

Prints the error with color (if enabled) and detail. Returns a string that indicates the abort condition such as “aborting due to i/o error”.

This function is called on Drop to display the error message. By contrast, the Display implementation prints a succinct version of the error, without detail.

if let Err(error) = rocket::build().launch().await {
    let abort = error.pretty_print();
    panic!("{}", abort);
}

Trait Implementations

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Drop for Error

fn drop(&mut self)

Executes the destructor for this type.

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<ErrorKind> for Error

fn from(kind: ErrorKind) -> Self

Converts to this type from the input type.