How to deserialize a `Response` in this middleware? #2539

frederikhors · 2024-01-25T19:03:40Z

frederikhors
Jan 25, 2024

Summary

Since this is an hot path of my backend I would like to better understand what is goiing on.

How can I get the JSON at the end of fn check()?

/*
[dependencies]
axum = { version = "0.7.4" }
tokio = { version = "1.0", features = ["full"] }
hyper = { version = "1.1.0", features = ["full"] }
hyper-util = { version = "0.1.2", features = [
    "client",
    "client-legacy",
    "http1",
] }
http-body-util = { version = "0.1.0" }
nanoserde = { version = "0.1.35" }
*/

use axum::{
    body::Body,
    extract::{Request, State},
    http::StatusCode,
    middleware::{self, Next},
    response::{Html, Response},
    routing::get,
    Router,
};
use http_body_util::BodyExt;
use hyper_util::{
    client::legacy::{self, connect::HttpConnector},
    rt::TokioExecutor,
};
use nanoserde::DeJson;
use std::sync::Arc;

pub struct AppState {
    pub hyper_client: legacy::Client<HttpConnector, Body>,
}

#[derive(nanoserde::DeJson, Clone)]
pub struct ResponseAsJson {
    id: String,
    name: String,
}

#[tokio::main]
async fn main() {
    let hyper_client = legacy::Client::builder(TokioExecutor::new()).build_http();

    let app_state = Arc::new(AppState { hyper_client });

    let app = Router::new()
        .route("/", get(handler))
        .route_layer(middleware::from_fn_with_state(app_state.clone(), check));

    let listener = tokio::net::TcpListener::bind("127.0.0.1:3000")
        .await
        .unwrap();

    axum::serve(listener, app.with_state(app_state).into_make_service())
        .await
        .unwrap();
}

async fn handler() -> Html<&'static str> {
    Html("<h1>Hello, World!</h1>")
}

async fn check(
    State(state): State<Arc<AppState>>,
    mut req: Request<Body>,
    next: Next,
) -> Result<Response, StatusCode> {
    let cookie = req
        .headers()
        .get("Cookie")
        .and_then(|c| c.to_str().ok())
        .unwrap_or("");

    let response = state
        .hyper_client
        .request(
            Request::builder()
                .uri("/check")
                .header("Cookie", cookie)
                .body(Body::empty())
                .unwrap(),
        )
        .await;

    if let Ok(resp) = response {
        // How to retrieve the JSON here?
        let response_as_json = ResponseAsJson::deserialize_json(resp);

        if response_as_json.is_ok() {
            req.extensions_mut().insert(response_as_json);

            return Ok(next.run(req).await);
        }
    }

    Err(StatusCode::UNAUTHORIZED)
}

axum version

0.7

frederikhors · 2024-01-25T19:09:23Z

frederikhors
Jan 25, 2024
Author

It works if I use the below code, but I'm a bit scared about all this code in this hot path middleware, is there something I can remove?

let mut body = resp.collect().await.unwrap().aggregate();

let response_as_json = ResponseAsJson::deserialize_json(&body.copy_to_bytes(body.remaining()));

3 replies

davidpdrsn Jan 25, 2024
Collaborator

I don't really understand what you're asking. I'm not familiar with nanoserde.

frederikhors Jan 25, 2024
Author

Sorry, it needs a &str (https://docs.rs/nanoserde/latest/nanoserde/trait.DeJson.html#method.deserialize_json).

How can I get a &str from response?

davidpdrsn Jan 25, 2024
Collaborator

Thats a very strange API 🤔 why does it require a string and not just a byte buffer? Oh well. Maybe just use serde instead 😅

You can use https://docs.rs/axum/latest/axum/body/fn.to_bytes.html to convert the body into a Bytes and then convert that into a &str with https://doc.rust-lang.org/stable/std/str/fn.from_utf8.html

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How to deserialize a Response in this middleware? #2539

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frederikhors Jan 25, 2024

Summary

axum version

Replies: 1 comment · 3 replies

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frederikhors Jan 25, 2024 Author

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davidpdrsn Jan 25, 2024 Collaborator

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davidpdrsn Jan 25, 2024 Collaborator

How to deserialize a `Response` in this middleware? #2539

frederikhors
Jan 25, 2024

Replies: 1 comment 3 replies

frederikhors
Jan 25, 2024
Author

davidpdrsn Jan 25, 2024
Collaborator

frederikhors Jan 25, 2024
Author

davidpdrsn Jan 25, 2024
Collaborator