Add type safe state extractor (#1155)

* begin threading the state through

* Pass state to extractors

* make state extractor work

* make sure nesting with different states work

* impl Service for MethodRouter<()>

* Fix some of axum-macro's tests

* Implement more traits for `State`

* Update examples to use `State`

* consistent naming of request body param

* swap type params

* Default the state param to ()

* fix docs references

* Docs and handler state refactoring

* docs clean ups

* more consistent naming

* when does MethodRouter implement Service?

* add missing docs

* use `Router`'s default state type param

* changelog

* don't use default type param for FromRequest and RequestParts

probably safer for library authors so you don't accidentally forget

* fix examples

* minor docs tweaks

* clarify how to convert handlers into services

* group methods in one impl block

* make sure merged `MethodRouter`s can access state

* fix docs link

* test merge with same state type

* Document how to access state from middleware

* Port cookie extractors to use state to extract keys (#1250)

* Updates ECOSYSTEM with a new sample project (#1252)

* Avoid unhelpful compiler suggestion (#1251)

* fix docs typo

* document how library authors should access state

* Add `RequestParts::with_state`

* fix example

* apply suggestions from review

* add relevant changes to axum-extra and axum-core changelogs

* Add `route_service_with_tsr`

* fix trybuild expectations

* make sure `SpaRouter` works with routers that have state

* Change order of type params on FromRequest and RequestParts

* reverse order of `RequestParts::with_state` args to match type params

* Add `FromRef` trait (#1268)

* Add `FromRef` trait

* Remove unnecessary type params

* format

* fix docs link

* format examples

* Avoid unnecessary `MethodRouter`

* apply suggestions from review

Co-authored-by: Dani Pardo <[email protected]>
Co-authored-by: Jonas Platte <[email protected]>

examples/sqlx-postgres/src/main.rs

@@ -15,7 +15,7 @@
 
 use axum::{
     async_trait,
-    extract::{Extension, FromRequest, RequestParts},
+    extract::{FromRequest, RequestParts, State},
     http::StatusCode,
     routing::get,
     Router,
@@ -46,12 +46,10 @@ async fn main() {
         .expect("can connect to database");
 
     // build our application with some routes
-    let app = Router::new()
-        .route(
-            "/",
-            get(using_connection_pool_extractor).post(using_connection_extractor),
-        )
-        .layer(Extension(pool));
+    let app = Router::with_state(pool).route(
+        "/",
+        get(using_connection_pool_extractor).post(using_connection_extractor),
+    );
 
     // run it with hyper
     let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
@@ -62,9 +60,9 @@ async fn main() {
         .unwrap();
 }
 
-// we can extract the connection pool with `Extension`
+// we can extract the connection pool with `State`
 async fn using_connection_pool_extractor(
-    Extension(pool): Extension<PgPool>,
+    State(pool): State<PgPool>,
 ) -> Result<String, (StatusCode, String)> {
     sqlx::query_scalar("select 'hello world from pg'")
         .fetch_one(&pool)
@@ -77,16 +75,14 @@ async fn using_connection_pool_extractor(
 struct DatabaseConnection(sqlx::pool::PoolConnection<sqlx::Postgres>);
 
 #[async_trait]
-impl<B> FromRequest<B> for DatabaseConnection
+impl<B> FromRequest<PgPool, B> for DatabaseConnection
 where
     B: Send,
 {
     type Rejection = (StatusCode, String);
 
-    async fn from_request(req: &mut RequestParts<B>) -> Result<Self, Self::Rejection> {
-        let Extension(pool) = Extension::<PgPool>::from_request(req)
-            .await
-            .map_err(internal_error)?;
+    async fn from_request(req: &mut RequestParts<PgPool, B>) -> Result<Self, Self::Rejection> {
+        let pool = req.state().clone();
 
         let conn = pool.acquire().await.map_err(internal_error)?;