added some error logging for extractors: Data, Json, Query, and Path (#765)

* added some error logging for extractors

* changed log::error to log::debug and fixed position of log for path

* added request path to debug logs

src/data.rs

@@ -96,6 +96,8 @@ impl<T: 'static, P> FromRequest<P> for Data<T> {
         if let Some(st) = req.app_config().extensions().get::<Data<T>>() {
             Ok(st.clone())
         } else {
+            log::debug!("Failed to construct App-level Data extractor. \
+                         Request path: {:?}", req.path());
             Err(ErrorInternalServerError(
                 "App data is not configured, to configure use App::data()",
             ))
@@ -235,6 +237,7 @@ impl<T: 'static, P> FromRequest<P> for RouteData<T> {
         if let Some(st) = req.route_data::<T>() {
             Ok(st.clone())
         } else {
+            log::debug!("Failed to construct Route-level Data extractor");
             Err(ErrorInternalServerError(
                 "Route data is not configured, to configure use Route::data()",
             ))

src/types/json.rs

@@ -179,10 +179,14 @@ where
             .map(|c| (c.limit, c.ehandler.clone()))
             .unwrap_or((32768, None));
 
+        let path = req.path().to_string();
+
         Box::new(
             JsonBody::new(req, payload)
                 .limit(limit)
                 .map_err(move |e| {
+                    log::debug!("Failed to deserialize Json from payload. \
+                                 Request path: {:?}", path);
                     if let Some(err) = err {
                         (*err)(e, &req2)
                     } else {

src/types/query.rs

@@ -122,6 +122,10 @@ where
     fn from_request(req: &HttpRequest, _: &mut Payload<P>) -> Self::Future {
         serde_urlencoded::from_str::<T>(req.query_string())
             .map(|val| Ok(Query(val)))
-            .unwrap_or_else(|e| Err(e.into()))
+            .unwrap_or_else(|e| {
+                log::debug!("Failed during Query extractor deserialization. \
+                             Request path: {:?}", req.path());  
+                Err(e.into())
+            })
     }
 }