Trait bound is not satisfied when attempting to use with_state()

[AnthonysDevAccount]

Summary

Hi. I get the following errors when running cargo check:

error[E0277]: the trait bound for<'a> Router<AppState>: tower_service::Service<IncomingStream<'a>> is not satisfied
--> src\main.rs:13:27
|
13 | axum::serve(listener, app).await.unwrap();
| ----------- ^^^ the trait for<'a> tower_service::Service<IncomingStream<'a>> is not implemented for Router<AppState>
| |
| required by a bound introduced by this call
|
= help: the following other types implement trait tower_service::Service<Request>:
<Router as tower_service::Service<axum::http::Request>>
<Router as tower_service::Service<IncomingStream<'_>>>
note: required by a bound in serve
--> C:\Users\admin.cargo\registry\src\index.crates.io-6f17d22bba15001f\axum-0.7.5\src\serve.rs:97:8
|
95 | pub fn serve<M, S>(tcp_listener: TcpListener, make_service: M) -> Serve<M, S>
| ----- required by a bound in this function
96 | where
97 | M: for<'a> Service<IncomingStream<'a>, Error = Infallible, Response = S>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in serve

error[E0277]: the trait bound Serve<Router<AppState>, _>: IntoFuture is not satisfied
--> src\main.rs:13:32
|
13 | axum::serve(listener, app).await.unwrap();
| ---------------------------^^^^^
| | ||
| | |the trait IntoFuture is not implemented for Serve<Router<AppState>, _>
| | help: remove the .await
| this call returns Serve<Router<AppState>, _>
|
= help: the trait IntoFuture is implemented for Serve<M, S>

For more information about this error, try rustc --explain E0277.
error: could not compile web (bin "web") due to 2 previous errors

I'm new to Axum so I apologise if the solution is obvious. Any help would be appreciated.

Following is the source code:

use axum::routing::get;

#[tokio::main]
async fn main() {
let shared_state: AppState = AppState { num: 42 };
let app = setup_routing(shared_state);
let listener = tokio::net::TcpListener::bind("localhost:5000").await.unwrap();
axum::serve(listener, app).await.unwrap();
}

#[allow(dead_code)]
fn setup_routing(shared_state: AppState) -> axum::Router {
axum::Router::new()
.fallback(fallback)
.nest_service("/static", tower_http::services::ServeDir::new("static"))
.route("/", get(get_root))
.route("/show-state", get(show_state))
.with_state::(shared_state) // only adds state to all prior routes
}

async fn show_state(axum::extract::State(shared_state): axum::extract::State) -> String {
format!("shared state = {shared_state:?}")
}

async fn fallback(uri: axum::http::Uri) -> impl axum::response::IntoResponse {
(axum::http::StatusCode::NOT_FOUND, format!("No route {uri}"))
}

async fn get_root() -> axum::response::Html<&'static str> {
include_str!("../static/root.html").into()
}

#[derive(Clone, Debug, Copy)]
#[allow(dead_code)]
pub struct AppState {
num: i32,
}

axum version

0.7.5

[wangziling]

Hi you need to remove the turbo fish (double colons) next to the .with_state.
And then you need to point the axum::extract::State's generic type thru axum::extract::State<AppState>.

The final code is below:

use axum::routing::get;

#[tokio::main]
async fn main() {
    let shared_state: AppState = AppState { num: 42 };
    let app = setup_routing(shared_state);
    let listener = tokio::net::TcpListener::bind("localhost:5000")
        .await
        .unwrap();
    axum::serve(listener, app).await.unwrap();
}

#[allow(dead_code)]
fn setup_routing(shared_state: AppState) -> axum::Router {
    axum::Router::new()
        .fallback(fallback)
        .nest_service("/static", tower_http::services::ServeDir::new("static"))
        .route("/", get(get_root))
        .route("/show-state", get(show_state))
        .with_state(shared_state) // only adds state to all prior routes
}

async fn show_state(axum::extract::State(shared_state): axum::extract::State<AppState>) -> String {
    format!("shared state = {shared_state:?}")
}

async fn fallback(uri: axum::http::Uri) -> impl axum::response::IntoResponse {
    (axum::http::StatusCode::NOT_FOUND, format!("No route {uri}"))
}

async fn get_root() -> axum::response::Html<&'static str> {
    include_str!("../static/root.html").into()
}

#[derive(Clone, Debug, Copy)]
#[allow(dead_code)]
pub struct AppState {
    num: i32,
}

[AnthonysDevAccount]

Hi. That worked!
Thanks for your help.