use hyper::{Body, Request, Response, Server, StatusCode}; use routerify::{Router, RouterService}; use std::fmt; use std::net::SocketAddr; // Define a custom error enum to model a possible API service error. #[derive(Debug)] enum ApiError { #[allow(dead_code)] Unauthorized, Generic(String), } impl std::error::Error for ApiError {} impl fmt::Display for ApiError { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match self { ApiError::Unauthorized => write!(f, "Unauthorized"), ApiError::Generic(s) => write!(f, "Generic: {}", s), } } } // Router, handlers and middleware must use the same error type. // In this case it's `ApiError`. // A handler for "/" page. async fn home_handler(_: Request) -> Result, ApiError> { // Simulate failure by returning `ApiError::Generic` variant. Err(ApiError::Generic("Something went wrong!".into())) } // Define an error handler function which will accept the `routerify::RouteError` // and generates an appropriate response. async fn error_handler(err: routerify::RouteError) -> Response { // Because `routerify::RouteError` is a boxed error, it must be // downcasted first. Unwrap for simplicity. let api_err = err.downcast::().unwrap(); // Now that we've got the actual error, we can handle it // appropriately. match api_err.as_ref() { ApiError::Unauthorized => Response::builder() .status(StatusCode::UNAUTHORIZED) .body(Body::empty()) .unwrap(), ApiError::Generic(s) => Response::builder() .status(StatusCode::INTERNAL_SERVER_ERROR) .body(Body::from(s.to_string())) .unwrap(), } } fn router() -> Router { // Create a router and specify the the handlers. Router::builder() .get("/", home_handler) // Specify the error handler to handle any errors caused by // a route or any middleware. .err_handler(error_handler) .build() .unwrap() } #[tokio::main] async fn main() { let router = router(); // Create a Service from the router above to handle incoming requests. let service = RouterService::new(router).unwrap(); // The address on which the server will be listening. let addr = SocketAddr::from(([127, 0, 0, 1], 3001)); // Create a server by passing the created service to `.serve` method. let server = Server::bind(&addr).serve(service); println!("App is running on: {}", addr); if let Err(err) = server.await { eprintln!("Server error: {}", err); } }