Errors when moving to actix-web 3.0 - rust

Question

Better late than never and so I started re-learning Rust and decided to focus on actix and actix-web.
I have these codes running in actix-web 1.0 and it seems not to run in actix-web 3.0:
main.rs
use messages_actix::MessageApp;
fn main() -> std::io::Result<()> {
std::env::set_var("RUST_LOG", "actix_web=info");
env_logger::init();
let app = MessageApp::new(8081);
app.run() // error here
}
error: "no method named run found for opaque type impl std::future::Future in the current scope method not found in impl std::future::Future
lib.rs
#[macro_use]
extern crate actix_web;
use actix_web::{middleware, web, App, HttpRequest, HttpServer, Result};
use serde::Serialize;
pub struct MessageApp {
pub port: u16,
}
#[derive(Serialize)]
pub struct IndexResponse{
pub message: String,
}
#[get("/")]
pub fn index(req: HttpRequest) -> Result<web::Json<IndexResponse>> { // error here
let hello = req
.headers()
.get("hello")
.and_then(|v| v.to_str().ok())
.unwrap_or_else(|| "world");
Ok(web::Json(IndexResponse {
message: hello.to_owned(),
}))
}
error for index: the trait Factory<_, _, _> is not implemented for fn(HttpRequest) -> std::result::Result<Json<IndexResponse>, actix_web::Error> {<index as HttpServiceFactory>::register::index}
impl MessageApp {
pub fn new(port: u16) -> Self {
MessageApp{ port }
}
pub fn run(&self) -> std::io::Result<()> {
println!("Starting HTTP server at 127.0.0.1:{}", self.port);
HttpServer::new(move || {
App::new()
.wrap(middleware::Logger::default())
.service(index)
})
.bind(("127.0.0.1", self.port))?
.workers(8)
.run() //error here
}
}
error: expected enum std::result::Result, found struct Server
checked the migration doc yet can't find what I'm looking for in relation to the errors listed.
Any help greatly appreciated...Thanks...

Answer 1

Newer versions of actix-web now use the async-await syntax, which was made stable as of Rust 1.39. You have to make your handlers async:
#[get("/")]
pub async fn index(req: HttpRequest) -> Result<web::Json<IndexResponse>> {
// ...
}
Creating an HttpServer is now an async operation:
impl MessageApp {
pub fn run(&self) -> std::io::Result<()>
HttpServer::new(...)
.run()
.await
}
}
And you can use the main macro to use async/await in your main function:
#[actix_web::main]
async fn main() -> std::io::Result<()> {
let app = MessageApp::new(8081);
app.run().await
}