pkg/shelf

pkg/shelf/lib/src/handlers/logger.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library shelf.handlers.logger;
+
+import 'package:stack_trace/stack_trace.dart';
+
+import '../middleware.dart';
+import '../util.dart';
+
+/// Middleware which prints the time of the request, the elapsed time for the
+/// inner handlers, the response's status code and the request URI.
+///
+/// [logger] takes two paramaters.
+///
+/// `msg` includes the request time, duration, request method, and requested
+/// path.
+///
+/// For successful requests, `msg` also includes the status code.
+///
+/// When an error is thrown, `isError` is true and `msg` contains the error
+/// description and stack trace.
+Middleware logRequests({void logger(String msg, bool isError)}) =>
+    (innerHandler) {
+  if (logger == null) logger = _defaultLogger;
+
+  return (request) {
+    var startTime = new DateTime.now();
+    var watch = new Stopwatch()..start();
+
+    return syncFuture(() => innerHandler(request)).then((response) {
+      var msg = _getMessage(startTime, response.statusCode, request.pathInfo,
+          request.method, watch.elapsed);
+
+      logger(msg, false);
+
+      return response;
+    }, onError: (error, stackTrace) {
+      var msg = _getErrorMessage(startTime, request.pathInfo, request.method,
+          watch.elapsed, error, stackTrace);
+
+      logger(msg, true);
+
+      throw error;
+    });
+  };
+};
+
+String _getMessage(DateTime requestTime, int statusCode, String pathInfo,
+  String method, Duration elapsedTime) {
+
+  return '${requestTime}\t$elapsedTime\t$method\t[${statusCode}]\t${pathInfo}';
+}
+
+String _getErrorMessage(DateTime requestTime, String pathInfo,
+  String method, Duration elapsedTime, Object error, StackTrace stack) {
+
+  var chain = new Chain.current();
+  if (stack != null) {
+    chain = new Chain.forTrace(stack)
+      .foldFrames((frame) => frame.isCore || frame.package == 'shelf')
+      .terse;
+  }
+
+  var msg = '${requestTime}\t$elapsedTime\t$method\t${pathInfo}\n$error';
+  if(chain == null) return msg;
+
+  return '$msg\n$chain';
+}
+
+void _defaultLogger(String msg, bool isError) {
+  if (isError) {
+    print('[ERROR] $msg');
+  } else {
+    print(msg);
+  }
+}