Cannot merge Routers whose handlers require application state

[sofiaritz]

Summary

I'm trying to do something similar to what's done in this example: https://github.com/tokio-rs/axum/blob/main/examples/key-value-store/src/main.rs#L116

But I am getting an error that I cannot fully understand nor fix, I hope someone can shine some light on this issue :)

Compilation error

error[E0277]: the trait bound `Router: From<Router<AppState>>` is not satisfied
   --> compmgr_server/src/main.rs:77:16
    |
77  |         .merge(web_index())
    |          ----- ^^^^^^^^^^^ the trait `From<Router<AppState>>` is not implemented for `Router`, which is required by `Router<AppState>: Into<Router>`
    |          |
    |          required by a bound introduced by this call
    |
    = note: required for `Router<AppState>` to implement `Into<Router>`
note: required by a bound in `Router::<S>::merge`
   --> /home/sofia/.cargo/registry/src/index.crates.io-6f17d22bba15001f/axum-0.7.4/src/routing/mod.rs:226:12
    |
224 |     pub fn merge<R>(self, other: R) -> Self
    |            ----- required by a bound in this associated function
225 |     where
226 |         R: Into<Router<S>>,
    |            ^^^^^^^^^^^^^^^ required by this bound in `Router::<S>::merge`
error[E0277]: the trait bound `Router: From<Router<AppState>>` is not satisfied

--> compmgr_server/src/main.rs:78:16

|

78  |         .merge(other_router(token))

|          ----- ^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From<Router<AppState>>` is not implemented for `Router`, which is required by `Router<AppState>: Into<Router>`

|          |

|          required by a bound introduced by this call

|

= note: required for `Router<AppState>` to implement `Into<Router>`

note: required by a bound in `Router::<S>::merge`

--> /home/sofia/.cargo/registry/src/index.crates.io-6f17d22bba15001f/axum-0.7.4/src/routing/mod.rs:226:12

|

224 |     pub fn merge<R>(self, other: R) -> Self

|            ----- required by a bound in this associated function

225 |     where

226 |         R: Into<Router<S>>,

|            ^^^^^^^^^^^^^^^ required by this bound in `Router::<S>::merge`

// src/main.rs

// A macro to simplify the process of representing `askama` templates
macro_rules! template_route {
    //--snip
    ($name:ident, $path:literal => $file:literal: $struct:ident ($id:literal)) => {
        #[derive(Template)]
        #[template(path = $file)]
        struct $struct<'a> {
            active: &'a str,
        }

        fn $name() -> Router<$crate::AppState> {
            async fn route() -> impl IntoResponse {
                $struct { active: $id }
            }

            Router::<$crate::AppState>::new().route($path, get(route))
        }
    }
}

template_route!(web_index, "/" => "dashboard.html": IndexTemplate ("dashboard"));
template_route!(first_boot_tmpl, "/boot" => "first_boot.html": FirstBootTemplate ("first_boot"));

fn other_router(token: Option<String>) -> Router<crate::AppState> {
    #[debug_handler]
    async fn handler(
        State(state): State<crate::AppState>,
        //--snip
    ) -> Html<&'static str> {
        //--snip
    }

    if token.is_some() {
        Router::<crate::AppState>::new()
            .route("/boot", put(handler))
            .merge(first_boot_tmpl())
    } else {
        Router::<crate::AppState>::new()
    }
}

#[derive(Clone)]
struct AppState {
    // --snip
}

#[tokio::main]
async fn main() {
    // --snip
    let state = AppState {
        // --snip
    };
    let token: Option<String> = // --snip
    let router = Router::new()
        .with_state(state)
        // --snip
        .merge(web_index())
        .merge(other_router(token))
        .layer(TraceLayer::new_for_http())
        .layer(CookieManagerLayer::new());
}

axum version

0.7.4

[jplatte]

with_state only supplies the state to all routes added prior to the call. You need to supply the state after merging.

[sofiaritz]

Edit: Fixed by also explicitly specifying S as AppState in previous merges, thank you! :)