Extractors & Problem+

Path/Json/State handlers, EventBus, API problem+json errors.

Author guide — edit docs/.vitepress/plugin-sdk-guides/extractors.md, then pnpm docs:generate.

Handlers: typed extractors (Path, Query, Json, Form, State, Extension) via sova::extract — separate IntoHandler markers so classic async fn(req: Request) stays valid.

rust

use sova::extract::{Json, Path, State};

#[derive(serde::Deserialize)]
struct Id { id: String }

async fn show(Path(Id { id }): Path<Id>, State(db): State<Db>) -> Response {
    /* … */
}

vld schemas use VldParse (not serde Deserialize) — keep req.validate() / route validate for those types; use plain serde structs with extract::Json.

Events: app.events() returns a shared EventBus. Sync listeners run in the dispatching task:

rust

let bus = app.events();
bus.listen::<NoteCreated, _>(|e| tracing::info!(?e.note_id, "created"));
// later:
bus.dispatch(NoteCreated { note_id: 1, user_id: 2 });

API errors: App::api() maps framework Error to application/problem+json. App::web() negotiates via Accept: prefer text/html → minimal HTML error page; application/problem+json / application/json → Problem Details; otherwise text/plain. Router 404/405 use the same Accept-aware builder. Validation (sova-vld) uses Problem Details with an errors array.

Extractors & Problem+ ​

Extractors & Problem+