Add with-logging helper to add logging to exception handlers

Author: Deraen

CHANGELOG.md

@@ -1,3 +1,8 @@
+## Unreleased
+
+- Added `compojure.api.exception/with-logging` helper to add logging to exception handlers.
+  - Check extended wiki guide on [exception handling](https://github.com/metosin/compojure-api/wiki/Exception-handling#logging)
+
 ## 0.24.4 (13.1.2016)
 
 **[compare](https://github.com/metosin/compojure-api/compare/0.24.3...0.24.4)**

src/compojure/api/exception.clj

@@ -57,6 +57,15 @@
                           :else "parse-exception")
                   :message (.getMessage cause)})))
 
+;;
+;; Logging
+;;
+
+(defn with-logging [handler]
+  (fn [^Exception e data req]
+    (logging/log! :error e (.getMessage e))
+    (handler e data req)))
+
 ;;
 ;; Mappings from other Exception types to our base types
 ;;

test/compojure/api/middleware_test.clj

@@ -1,5 +1,6 @@
 (ns compojure.api.middleware-test
   (:require [compojure.api.middleware :refer :all]
+            [compojure.api.exception :as ex]
             [midje.sweet :refer :all]
             [ring.util.http-response :refer [ok]]
             [ring.util.http-status :as status]
@@ -39,23 +40,43 @@
 
     (ring.util.test/string-input-stream "foobar") false false))
 
+(def default-options (:exceptions api-middleware-defaults))
+
 (facts "wrap-exceptions"
   (with-out-str
-    (without-err
-      (let [exception (RuntimeException. "kosh")
-            exception-class (.getName (.getClass exception))
-            handler (-> (fn [_] (throw exception))
-                        (wrap-exceptions {}))]
+   (without-err
+     (let [exception (RuntimeException. "kosh")
+           exception-class (.getName (.getClass exception))
+           handler (-> (fn [_] (throw exception))
+                       (wrap-exceptions default-options))]
 
-        (fact "converts exceptions into safe internal server errors"
-          (handler {}) => (contains {:status status/internal-server-error
-                                     :body (contains {:class exception-class
-                                                      :type "unknown-exception"})})))))
+       (fact "converts exceptions into safe internal server errors"
+         (handler {}) => (contains {:status status/internal-server-error
+                                    :body (contains {:class exception-class
+                                                     :type "unknown-exception"})})))))
 
   (with-out-str
    (without-err
      (fact "Slingshot exception map type can be matched"
        (let [handler (-> (fn [_] (throw+ {:type ::test} (RuntimeException. "kosh")))
-                         (wrap-exceptions {:handlers {::test (fn [ex _ _] {:status 500 :body "hello"})}}))]
+                         (wrap-exceptions (assoc-in default-options [:handlers ::test] (fn [ex _ _] {:status 500 :body "hello"}))))]
          (handler {}) => (contains {:status status/internal-server-error
-                                    :body "hello"}))))))
+                                    :body "hello"})))))
+
+  (without-err
+    (fact "Default handler logs exceptions to console"
+      (let [handler (-> (fn [_] (throw (RuntimeException. "kosh")))
+                        (wrap-exceptions default-options))]
+        (with-out-str (handler {})) => "ERROR kosh\n")))
+
+  (without-err
+    (fact "Default request-parsing handler does not log messages"
+      (let [handler (-> (fn [_] (throw (ex-info "Error parsing request" {:type ::ex/request-parsing} (RuntimeException. "Kosh"))))
+                        (wrap-exceptions default-options))]
+        (with-out-str (handler {})) => "")))
+
+  (without-err
+    (fact "Logging can be added to a exception handler"
+      (let [handler (-> (fn [_] (throw (ex-info "Error parsing request" {:type ::ex/request-parsing} (RuntimeException. "Kosh"))))
+                        (wrap-exceptions (assoc-in default-options [:handlers ::ex/request-parsing] (ex/with-logging ex/request-parsing-handler))))]
+        (with-out-str (handler {})) => "ERROR Error parsing request\n"))))