actix-website/examples/responder-trait/src/main.rs

// <responder-trait>
use actix_web::{Error, HttpRequest, HttpResponse, Responder};
use serde::Serialize;
use futures::future::{ready, Ready};

#[derive(Serialize)]
struct MyObj {
    name: &'static str,
}

// Responder
impl Responder for MyObj {
    type Error = Error;
    type Future = Ready<Result<HttpResponse, Error>>;

    fn respond_to(self, _req: &HttpRequest) -> Self::Future {
        let body = serde_json::to_string(&self).unwrap();

        // Create response and set content type
        ready(Ok(HttpResponse::Ok()
            .content_type("application/json")
            .body(body)))
    }
}

async fn index() -> impl Responder {
    MyObj { name: "user" }
}
// </responder-trait>

#[actix_rt::main]
async fn main() -> std::io::Result<()> {
    use actix_web::{web, App, HttpServer};

    HttpServer::new(|| App::new().route("/", web::get().to(index)))
        .bind("127.0.0.1:8088")?
        .run()
        .await
}