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]>

axum-extra/src/routing/resource.rs

@@ -1,13 +1,9 @@
 use axum::{
     body::Body,
     handler::Handler,
-    http::Request,
-    response::IntoResponse,
-    routing::{delete, get, on, post, MethodFilter},
+    routing::{delete, get, on, post, MethodFilter, MethodRouter},
     Router,
 };
-use std::{convert::Infallible, fmt};
-use tower_service::Service;
 
 /// A resource which defines a set of conventional CRUD routes.
 ///
@@ -34,14 +30,15 @@ use tower_service::Service;
 ///     .destroy(|Path(user_id): Path<u64>| async {});
 ///
 /// let app = Router::new().merge(users);
-/// # let _: Router<axum::body::Body> = app;
+/// # let _: Router = app;
 /// ```
-pub struct Resource<B = Body> {
+#[derive(Debug)]
+pub struct Resource<S = (), B = Body> {
     pub(crate) name: String,
-    pub(crate) router: Router<B>,
+    pub(crate) router: Router<S, B>,
 }
 
-impl<B> Resource<B>
+impl<B> Resource<(), B>
 where
     B: axum::body::HttpBody + Send + 'static,
 {
@@ -49,16 +46,29 @@ where
     ///
     /// All routes will be nested at `/{resource_name}`.
     pub fn named(resource_name: &str) -> Self {
+        Self::named_with((), resource_name)
+    }
+}
+
+impl<S, B> Resource<S, B>
+where
+    B: axum::body::HttpBody + Send + 'static,
+    S: Clone + Send + Sync + 'static,
+{
+    /// Create a `Resource` with the given name and state.
+    ///
+    /// All routes will be nested at `/{resource_name}`.
+    pub fn named_with(state: S, resource_name: &str) -> Self {
         Self {
             name: resource_name.to_owned(),
-            router: Default::default(),
+            router: Router::with_state(state),
         }
     }
 
     /// Add a handler at `GET /{resource_name}`.
     pub fn index<H, T>(self, handler: H) -> Self
     where
-        H: Handler<T, B>,
+        H: Handler<T, S, B>,
         T: 'static,
     {
         let path = self.index_create_path();
@@ -68,7 +78,7 @@ where
     /// Add a handler at `POST /{resource_name}`.
     pub fn create<H, T>(self, handler: H) -> Self
     where
-        H: Handler<T, B>,
+        H: Handler<T, S, B>,
         T: 'static,
     {
         let path = self.index_create_path();
@@ -78,7 +88,7 @@ where
     /// Add a handler at `GET /{resource_name}/new`.
     pub fn new<H, T>(self, handler: H) -> Self
     where
-        H: Handler<T, B>,
+        H: Handler<T, S, B>,
         T: 'static,
     {
         let path = format!("/{}/new", self.name);
@@ -88,7 +98,7 @@ where
     /// Add a handler at `GET /{resource_name}/:{resource_name}_id`.
     pub fn show<H, T>(self, handler: H) -> Self
     where
-        H: Handler<T, B>,
+        H: Handler<T, S, B>,
         T: 'static,
     {
         let path = self.show_update_destroy_path();
@@ -98,7 +108,7 @@ where
     /// Add a handler at `GET /{resource_name}/:{resource_name}_id/edit`.
     pub fn edit<H, T>(self, handler: H) -> Self
     where
-        H: Handler<T, B>,
+        H: Handler<T, S, B>,
         T: 'static,
     {
         let path = format!("/{0}/:{0}_id/edit", self.name);
@@ -108,7 +118,7 @@ where
     /// Add a handler at `PUT or PATCH /resource_name/:{resource_name}_id`.
     pub fn update<H, T>(self, handler: H) -> Self
     where
-        H: Handler<T, B>,
+        H: Handler<T, S, B>,
         T: 'static,
     {
         let path = self.show_update_destroy_path();
@@ -118,7 +128,7 @@ where
     /// Add a handler at `DELETE /{resource_name}/:{resource_name}_id`.
     pub fn destroy<H, T>(self, handler: H) -> Self
     where
-        H: Handler<T, B>,
+        H: Handler<T, S, B>,
         T: 'static,
     {
         let path = self.show_update_destroy_path();
@@ -133,13 +143,8 @@ where
         format!("/{0}/:{0}_id", self.name)
     }
 
-    fn route<T>(mut self, path: &str, svc: T) -> Self
-    where
-        T: Service<Request<B>, Error = Infallible> + Clone + Send + 'static,
-        T::Response: IntoResponse,
-        T::Future: Send + 'static,
-    {
-        self.router = self.router.route(path, svc);
+    fn route(mut self, path: &str, method_router: MethodRouter<S, B>) -> Self {
+        self.router = self.router.route(path, method_router);
         self
     }
 }
@@ -150,21 +155,13 @@ impl<B> From<Resource<B>> for Router<B> {
     }
 }
 
-impl<B> fmt::Debug for Resource<B> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("Resource")
-            .field("name", &self.name)
-            .field("router", &self.router)
-            .finish()
-    }
-}
-
 #[cfg(test)]
 mod tests {
     #[allow(unused_imports)]
     use super::*;
     use axum::{extract::Path, http::Method, Router};
-    use tower::ServiceExt;
+    use http::Request;
+    use tower::{Service, ServiceExt};
 
     #[tokio::test]
     async fn works() {
@@ -220,7 +217,7 @@ mod tests {
         );
     }
 
-    async fn call_route(app: &mut Router, method: Method, uri: &str) -> String {
+    async fn call_route(app: &mut Router<()>, method: Method, uri: &str) -> String {
         let res = app
             .ready()
             .await