better handler function ergonimics

src/application.rs

@@ -180,7 +180,7 @@ impl<S> ApplicationBuilder<S> where S: 'static {
     ///         .resource("/test", |r| {
     ///              r.get::<MyRoute>();
     ///              r.handler(Method::HEAD, |req, payload, state| {
-    ///                  httpcodes::HTTPMethodNotAllowed
+    ///                  Ok(httpcodes::HTTPMethodNotAllowed)
     ///              });
     ///         })
     ///         .finish();

src/error.rs

@@ -123,6 +123,13 @@ impl From<HttpError> for HttpResponse {
     }
 }
 
+/// Return `InternalServerError` for `io::Error`
+impl From<IoError> for HttpResponse {
+    fn from(err: IoError) -> Self {
+        HttpResponse::from_error(StatusCode::INTERNAL_SERVER_ERROR, err)
+    }
+}
+
 /// Return `BadRequest` for `cookie::ParseError`
 impl From<cookie::ParseError> for HttpResponse {
     fn from(err: cookie::ParseError) -> Self {

src/lib.rs

@@ -52,7 +52,7 @@ pub use httprequest::{HttpRequest, UrlEncoded};
 pub use httpresponse::{HttpResponse, HttpResponseBuilder};
 pub use payload::{Payload, PayloadItem, PayloadError};
 pub use route::{Route, RouteFactory, RouteHandler, RouteResult};
-pub use resource::{Reply, Resource};
+pub use resource::{Reply, Resource, HandlerResult};
 pub use recognizer::{Params, RouteRecognizer};
 pub use logger::Logger;
 pub use server::HttpServer;

src/resource.rs

@@ -15,6 +15,9 @@ use httprequest::HttpRequest;
 use httpresponse::HttpResponse;
 use httpcodes::{HTTPNotFound, HTTPMethodNotAllowed};
 
+/// Result of a resource handler function
+pub type HandlerResult<T> = Result<T, HttpResponse>;
+
 /// Http resource
 ///
 /// `Resource` is an entry in route table which corresponds to requested URL.
@@ -48,7 +51,6 @@ impl<S> Default for Resource<S> {
     }
 }
 
-
 impl<S> Resource<S> where S: 'static {
 
     pub(crate) fn default_not_found() -> Self {
@@ -66,7 +68,7 @@ impl<S> Resource<S> where S: 'static {
 
     /// Register handler for specified method.
     pub fn handler<F, R>(&mut self, method: Method, handler: F)
-        where F: Fn(&mut HttpRequest, Payload, &S) -> R + 'static,
+        where F: Fn(&mut HttpRequest, Payload, &S) -> HandlerResult<R> + 'static,
               R: Into<HttpResponse> + 'static,
     {
         self.routes.insert(method, Box::new(FnHandler::new(handler)));