add a way to configure error treatment for Query extractor

src/extractor.rs

@@ -200,17 +200,69 @@ impl<T, S> FromRequest<S> for Query<T>
 where
     T: de::DeserializeOwned,
 {
-    type Config = ();
+    type Config = QueryConfig<S>;
     type Result = Result<Self, Error>;
 
     #[inline]
-    fn from_request(req: &HttpRequest<S>, _: &Self::Config) -> Self::Result {
+    fn from_request(req: &HttpRequest<S>, cfg: &Self::Config) -> Self::Result {
+        let req2 = req.clone();
+        let err = Rc::clone(&cfg.ehandler);
         serde_urlencoded::from_str::<T>(req.query_string())
-            .map_err(|e| e.into())
+            .map_err(move |e| (*err)(e, &req2))
             .map(Query)
     }
 }
 
+/// Query extractor configuration
+///
+/// ```rust
+/// # extern crate actix_web;
+/// #[macro_use] extern crate serde_derive;
+/// use actix_web::{error, http, App, HttpResponse, Query, Result};
+///
+/// #[derive(Deserialize)]
+/// struct Info {
+///     username: String,
+/// }
+///
+/// /// deserialize `Info` from request's body, max payload size is 4kb
+/// fn index(info: Query<Info>) -> Result<String> {
+///     Ok(format!("Welcome {}!", info.username))
+/// }
+///
+/// fn main() {
+///     let app = App::new().resource("/index.html", |r| {
+///         r.method(http::Method::GET).with_config(index, |cfg| {
+///             cfg.0.error_handler(|err, req| {
+///                 // <- create custom error response
+///                 error::InternalError::from_response(err, HttpResponse::Conflict().finish()).into()
+///             });
+///         })
+///     });
+/// }
+/// ```
+pub struct QueryConfig<S> {
+    ehandler: Rc<Fn(serde_urlencoded::de::Error, &HttpRequest<S>) -> Error>,
+}
+impl<S> QueryConfig<S> {
+    /// Set custom error handler
+    pub fn error_handler<F>(&mut self, f: F) -> &mut Self
+    where
+        F: Fn(serde_urlencoded::de::Error, &HttpRequest<S>) -> Error + 'static,
+    {
+        self.ehandler = Rc::new(f);
+        self
+    }
+}
+
+impl<S> Default for QueryConfig<S> {
+    fn default() -> Self {
+        QueryConfig {
+            ehandler: Rc::new(|e, _| e.into()),
+        }
+    }
+}
+
 impl<T: fmt::Debug> fmt::Debug for Query<T> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         self.0.fmt(f)
@@ -959,7 +1011,7 @@ mod tests {
         assert_eq!(s.0, "name");
         assert_eq!(s.1, "user1");
 
-        let s = Query::<Id>::from_request(&req, &()).unwrap();
+        let s = Query::<Id>::from_request(&req, &QueryConfig::default()).unwrap();
         assert_eq!(s.id, "test");
 
         let mut router = Router::<()>::default();