Add support for impl Middleware to allow closure middleware

Author: nyxtom

examples/middleware.rs

@@ -1,5 +1,3 @@
-use std::future::Future;
-use std::pin::Pin;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Arc;
 
@@ -25,19 +23,17 @@ impl UserDatabase {
 // This is an example of a function middleware that uses the
 // application state. Because it depends on a specific request state,
 // it would likely be closely tied to a specific application
-fn user_loader(mut request: Request, next: Next) -> Pin<Box<dyn Future<Output = Result> + Send>> {
-    Box::pin(async {
-        if let Some(user) = request.state().find_user().await {
-            tide::log::trace!("user loaded", {user: user.name});
-            request.set_ext(user);
-            Ok(next.run(request).await)
-        // this middleware only needs to run before the endpoint, so
-        // it just passes through the result of Next
-        } else {
-            // do not run endpoints, we could not find a user
-            Ok(Response::new(StatusCode::Unauthorized))
-        }
-    })
+async fn user_loader(mut request: Request, next: Next) -> Result {
+    if let Some(user) = request.state().find_user().await {
+        tide::log::trace!("user loaded", {user: user.name});
+        request.set_ext(user);
+        Ok(next.run(request).await)
+    // this middleware only needs to run before the endpoint, so
+    // it just passes through the result of Next
+    } else {
+        // do not run endpoints, we could not find a user
+        Ok(Response::new(StatusCode::Unauthorized))
+    }
 }
 
 // This is an example of middleware that keeps its own state and could

src/middleware.rs

@@ -5,7 +5,6 @@ use std::sync::Arc;
 use crate::{Endpoint, Request, Response};
 use async_trait::async_trait;
 use std::future::Future;
-use std::pin::Pin;
 
 /// Middleware that wraps around the remaining middleware chain.
 #[async_trait]
@@ -20,15 +19,16 @@ pub trait Middleware: Send + Sync + 'static {
 }
 
 #[async_trait]
-impl<F> Middleware for F
+impl<F, Fut, Res> Middleware for F
 where
-    F: Send
-        + Sync
-        + 'static
-        + Fn(Request, Next) -> Pin<Box<dyn Future<Output = crate::Result> + Send>>,
+    F: Send + Sync + 'static + Fn(Request, Next) -> Fut,
+    Fut: Future<Output = crate::Result<Res>> + Send + 'static,
+    Res: Into<Response> + 'static,
 {
     async fn handle(&self, req: Request, next: Next) -> crate::Result {
-        (self)(req, next).await
+        let fut = (self)(req, next);
+        let res = fut.await?;
+        Ok(res.into())
     }
 }
 

src/server.rs

@@ -181,10 +181,7 @@ where
     ///
     /// Middleware can only be added at the "top level" of an application, and is processed in the
     /// order in which it is applied.
-    pub fn with<M>(&mut self, middleware: M) -> &mut Self
-    where
-        M: Middleware,
-    {
+    pub fn with(&mut self, middleware: impl Middleware) -> &mut Self {
         log::trace!("Adding middleware {}", middleware.name());
         let m = Arc::get_mut(&mut self.middleware)
             .expect("Registering middleware is not possible after the Server has started");

tests/function_middleware.rs

@@ -1,25 +1,18 @@
-use std::future::Future;
-use std::pin::Pin;
 use tide::http::{self, url::Url, Method};
 
 mod test_utils;
 
-fn auth_middleware(
-    request: tide::Request,
-    next: tide::Next,
-) -> Pin<Box<dyn Future<Output = tide::Result> + Send>> {
+async fn auth_middleware(request: tide::Request, next: tide::Next) -> tide::Result {
     let authenticated = match request.header("X-Auth") {
         Some(header) => header == "secret_key",
         None => false,
     };
 
-    Box::pin(async move {
-        if authenticated {
-            Ok(next.run(request).await)
-        } else {
-            Ok(tide::Response::new(tide::StatusCode::Unauthorized))
-        }
-    })
+    if authenticated {
+        Ok(next.run(request).await)
+    } else {
+        Ok(tide::Response::new(tide::StatusCode::Unauthorized))
+    }
 }
 
 async fn echo_path(req: tide::Request) -> tide::Result<String> {