Crate axum_debug

This is a debugging crate that provides better error messages for axum framework.

axum is a great framework for developing web applications. But when you make a mistake, error messages can be really complex and long. It can take a long time for you to figure out what is wrong in your code. This crate provides utilities to generate better error messages in case you make a mistake.

While using axum, you can get long error messages for simple mistakes. For example:

use axum::{handler::get, Router};

#[tokio::main]
async fn main() {
    let app = Router::new().route("/", get(handler));

    axum::Server::bind(&"0.0.0.0:3000".parse().unwrap())
        .serve(app.into_make_service())
        .await
        .unwrap();
}

fn handler() -> &'static str {
    "Hello, world"
}

You will get a long error message about function not implementing Handler trait. But why this function does not implement it? To figure it out debug_handler macro can be used.

#[debug_handler]
fn handler() -> &'static str {
    "Hello, world"
}

error: handlers must be async functions
  --> main.rs:xx:1
   |
xx | fn handler() -> &'static str {
   | ^^

As the error message says, handler function needs to be async.

Long Error Messages

Sometimes error messages are long even if you are using debug_handler. To make them shorter without missing anything important, you can use debug_router.

use axum::{handler::get, Router};
use axum_debug::{debug_handler, debug_router};

#[tokio::main]
async fn main() {
    let app = Router::new().route("/", get(handler));

    debug_router!(app);

    axum::Server::bind(&"0.0.0.0:3000".parse().unwrap())
        .serve(app.into_make_service())
        .await
        .unwrap();
}

#[debug_handler]
async fn handler() -> bool {
    false
}

Performance

Macros in this crate have no effect when using release profile. (eg. cargo build --release)

Macros

debug_router

Shortens error message when applied to a Router.

Functions

check_service

Checks if provided service can be used with Router.

debug_service

Checks and returns if provided service can be used with Router.

Attribute Macros

debug_handler

Generates better error messages when applied to a handler function.