How to retrieve sent appdata that contains traits within OpenApi?

[shyuen]

I'm learning Rust and was doing a project with Poem while implementing the Hexagonal Architecture Pattern.

From what I understand in Hexagonal Architecture, I should try to create a "service" that encapsulates a group functions which are called to wrappers around 3rd party libraries (adapters) through a standardized way via traits (ports).

That requires me to include an AppState that contains the "service" with a trait like so:

pub struct AppState<M: Meta> {
    pub meta: Arc<M>,
}

The trait is as follows:

pub trait Meta: Clone + Send + Sync + 'static {
    /// Get application metadata, such as version info, uptime, etc.
    async fn get_app_data(&self) -> Config; // Where Config is a struct with key value string pairs
}

I have a function called start_service and I'm able to pass the an AppState as follows:

async fn start_server(
        &self,
        config: &Webserver,
        meta: &impl Meta,
    ) -> Result<(), std::io::Error> {

        ...

        let app_state = AppState {
            meta: Arc::new(meta.clone()),
        };
        
       // Create Swagger UI
       let ui = main_paths.swagger_ui();
        
       // Create routes
       let routes = Route::new()
            .nest("/", main_paths)
            .nest(format!("{}/docs", &base_path), ui)
            .data(app_state.clone()); // Passing the app_state here compiles without issues
      ...
}

However, on the OpenAPI handler end I'm unable to retrieve that app_state:

pub struct MetaHandler;

/// API responses for Meta endpoints
#[derive(ApiResponse)]
enum MetaResponses {
    /// Returns information on application configuration in JSON.
    #[oai(status = 200)]
    Ok(Json<Value>),
}

#[OpenApi(prefix_path = "/meta", tag = "OperationalTags::Meta")]
impl MetaHandler {
    #[oai(path = "/info", method = "get", hidden = false)]
    async fn info<M>(&self, Data(app_state): Data<&AppState<M>>) -> MetaResponses
    where
        M: Meta,
    {
        // Return the configuration with app_state as JSON
        MetaResponses::Ok(Json(serde_json::json!(
            // Access the inner Config reference
            app_state.meta.get_app_data()
        )))
    }
}

I get error[E0412]: cannot find type 'M' in this scope

async fn info<M>(&self, Data(app_state): Data<&AppState<M>>) -> MetaResponses
                                                        ^ not found in this scope

If I take my info function and move it outside of #[OpenApi] and remove the &self. it seems that the function syntax for referencing the Meta trait is correct.

For example, this will compile without errors:

async fn info<M>(Data(_app_state): Data<&AppState<M>>) -> MetaResponses
where
    M: Meta,
{
      // Return the configuration with app_state as JSON
        MetaResponses::Ok(Json(serde_json::json!(
            // Access the inner Config reference
            app_state.meta.get_app_data()
        )))
}

Is this due to some limitation with using Data in Poem? If so, are there any workarounds?

Thanks in advance!