I'm trying to build a rest-api using Rocket, Diesel, and a PostGreSQL database. For this I've tried to "inject" the database connection into a GET method using the rocket_sync_db_pools crate for as quoted in the Rocket guide Rocket also provides support for synchronous, blocking ORMs like Diesel via the rocket_sync_db_pools library. Thus I have tried to stray away the code from using the following code from the Diesel documentation https://diesel.rs/guides/getting-started:
// main.rs
#[launch]
fn rocket() -> _ {
rocket::build()
.attach(user_controller::stage())
.attach(cors::CORS)
}
pub fn establish_connection() -> PgConnection {
dotenv().ok();
let database_url = env::var("DATABASE_URL").expect("DATABASE_URL must be set");
PgConnection::establish(&database_url)
.unwrap_or_else(|_| panic!("Error connecting to {}", database_url))
}
// user_controller.rs
#[get("/<user_id>")]
pub async fn read(user_id: i32) -> Option<Json<User>> {
let conn = &mut establish_connection();
let potential_user = users
.filter(id.eq(user_id))
.first(conn);
match potential_user {
Ok(user) => Some(Json(user)),
Err(NotFound) => None,
Err(_) => panic!("Internal server error")
}
}
pub fn stage() -> AdHoc {
AdHoc::on_ignite("User Mounts Stage", |rocket| async {
rocket.mount("/user", routes![read])
})
}
Into changing it as follows:
// main.rs
use rocket_sync_db_pools::{database, diesel::PgConnection};
#[database("postgres_db")]
pub struct Db(PgConnection);
#[launch]
fn rocket() -> _ {
rocket::build()
.attach(user_controller::stage())
.attach(CourseroDbConn::fairing())
.attach(cors::CORS)
}
// user_controller.rs
#[get("/<user_id>")]
async fn read(db: Db, user_id: i32) -> Option<Json<User>> {
db.run(move |conn| {
users
.filter(id.eq(user_id))
.first(conn)
}).await.map(Json).ok()
}
pub fn stage() -> AdHoc {
AdHoc::on_ignite("User Mounts Stage", |rocket| async {
rocket.mount("/user", routes![read])
})
}
I left out some sections such as the models used and the libraries used, but if they are required for solving this problem I would gladly post them. The versions of the libraries are:
[dependencies]
rocket = { version = "0.5.0-rc.2", features = ["json"] }
diesel = { version = "2.0.0", features = ["postgres"] }
[dependencies.rocket_sync_db_pools]
version = "0.1.0-rc.2"
features = ["diesel_postgres_pool"]
However, the error that shows up from the conn variable in the 2nd version that uses rocket_sync_db_pools is as the question post title describes it. The resources that I have tried to use are:
