How to implement versioned API in Rust

Implement versioned APIs in Rust by prefixing route paths with version numbers and using separate modules for each version's logic.

use actix_web::{web, App, HttpResponse, HttpServer, Responder};

mod v1 {
    use super::*;
    pub async fn get_user(id: web::Path<i32>) -> impl Responder {
        HttpResponse::Ok().body(format!("v1 user: {}", id.into_inner()))
    }
}

mod v2 {
    use super::*;
    pub async fn get_user(id: web::Path<i32>) -> impl Responder {
        HttpResponse::Ok().body(format!("v2 user: {}", id.into_inner()))
    }
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    HttpServer::new(|| {
        App::new()
            .service(web::scope("/api/v1").route("/users/{id}", web::get().to(v1::get_user)))
            .service(web::scope("/api/v2").route("/users/{id}", web::get().to(v2::get_user)))
    })
    .bind("127.0.0.1:8080")?
    .run()
    .await
}

Versioning an API means creating different versions of your endpoints so old clients don't break when you update the code. You achieve this by separating the logic for each version into its own file or module and assigning them to unique URL paths like /v1 and /v2. It is like having different editions of a book in a library; readers can choose the edition they need without affecting others.