examples/diesel/src/main.rs

//! Actix web diesel example
//!
//! Diesel does not support tokio, so we have to run it in separate threads.
//! Actix supports sync actors by default, so we going to create sync actor
//! that use diesel. Technically sync actors are worker style actors, multiple
//! of them can run in parallel and process messages from same queue.
#[macro_use]
extern crate diesel;
#[macro_use]
extern crate serde_derive;

use actix_web::{error, middleware, web, App, Error, HttpResponse, HttpServer};
use diesel::prelude::*;
use diesel::r2d2::{self, ConnectionManager};
use dotenv;

mod models;
mod schema;

type Pool = r2d2::Pool<ConnectionManager<SqliteConnection>>;

#[derive(Debug, Serialize, Deserialize)]
struct MyUser {
    name: String,
}

/// Diesel query
fn query(
    nm: String,
    pool: web::Data<Pool>,
) -> Result<models::User, diesel::result::Error> {
    use self::schema::users::dsl::*;

    let uuid = format!("{}", uuid::Uuid::new_v4());
    let new_user = models::NewUser {
        id: &uuid,
        name: nm.as_str(),
    };
    let conn: &SqliteConnection = &pool.get().unwrap();

    diesel::insert_into(users).values(&new_user).execute(conn)?;

    let mut items = users.filter(id.eq(&uuid)).load::<models::User>(conn)?;
    Ok(items.pop().unwrap())
}

/// Async request handler
async fn add(
    name: web::Path<String>,
    pool: web::Data<Pool>,
) -> Result<HttpResponse, Error> {
    // run diesel blocking code
    Ok(web::block(move || query(name.into_inner(), pool))
        .await
        .map(|user| HttpResponse::Ok().json(user))
        .map_err(|_| HttpResponse::InternalServerError())?)
}

/// This handler manually parse json object. Bytes object supports FromRequest trait (extractor)
/// and could be loaded from request payload automatically
async fn index_add(
    body: web::Bytes,
    pool: web::Data<Pool>,
) -> Result<HttpResponse, Error> {
    // body is loaded, now we can deserialize id with serde-json
    let r_obj = serde_json::from_slice::<MyUser>(&body);

    // Send to the db for create return response to peer
    match r_obj {
        Ok(obj) => {
            let user = web::block(move || query(obj.name, pool))
                .await
                .map_err(|_| Error::from(HttpResponse::InternalServerError()))?;
            Ok(HttpResponse::Ok().json(user))
        }
        Err(_) => Err(error::ErrorBadRequest("Json Decode Failed")),
    }
}

/// This handler offloads json deserialization to actix-web's Json extrator
async fn add2(
    item: web::Json<MyUser>,
    pool: web::Data<Pool>,
) -> Result<HttpResponse, Error> {
    // run diesel blocking code
    let user = web::block(move || query(item.into_inner().name, pool))
        .await
        .map_err(|_| HttpResponse::InternalServerError())?; // convert diesel error to http response

    Ok(HttpResponse::Ok().json(user))
}

#[actix_rt::main]
async fn main() -> std::io::Result<()> {
    std::env::set_var("RUST_LOG", "actix_web=info");
    env_logger::init();

    dotenv::dotenv().ok();

    let connspec = std::env::var("DATABASE_URL").expect("DATABASE_URL");
    let manager = ConnectionManager::<SqliteConnection>::new(connspec);
    let pool = r2d2::Pool::builder()
        .build(manager)
        .expect("Failed to create pool.");

    // Start http server
    HttpServer::new(move || {
        App::new()
            .data(pool.clone())
            // enable logger
            .wrap(middleware::Logger::default())
            // This can be called with:
            // curl -S --header "Content-Type: application/json" --request POST --data '{"name":"xyz"}'  http://127.0.0.1:8080/add
            // Use of the extractors makes some post conditions simpler such
            // as size limit protections and built in json validation.
            .service(
                web::resource("/add2")
                    .data(
                        web::JsonConfig::default()
                            .limit(4096) // <- limit size of the payload
                            .error_handler(|err, _| {
                                // <- create custom error response
                                error::InternalError::from_response(
                                    err,
                                    HttpResponse::Conflict().finish(),
                                )
                                .into()
                            }),
                    )
                    .route(web::post().to(add2)),
            )
            //  Manual parsing would allow custom error construction, use of
            //  other parsers *beside* json (for example CBOR, protobuf, xml), and allows
            //  an application to standardise on a single parser implementation.
            .service(web::resource("/add").route(web::post().to(index_add)))
            .service(web::resource("/add/{name}").route(web::get().to(add)))
    })
    .bind("127.0.0.1:8080")?
    .start()
    .await
}