Move logError to app-level binding

packages/core/src/application.ts

@@ -59,6 +59,8 @@ export class Application extends Context {
 
     this.handleHttp = (req: ServerRequest, res: ServerResponse) =>
       this._handleHttpRequest(req, res);
+
+    this.bind('logError').to(this._logError.bind(this));
   }
 
   protected _handleHttpRequest(request: ServerRequest, response: ServerResponse) {
@@ -100,6 +102,11 @@ export class Application extends Context {
   public controller<T>(controllerCtor: Constructor<T>): Binding {
     return this.bind('controllers.' + controllerCtor.name).toClass(controllerCtor);
   }
+
+  protected _logError(err: Error, statusCode: number, req: ServerRequest): void {
+    console.error('Unhandled error in %s %s: %s %s',
+      req.method, req.url, statusCode, err.stack || err);
+  }
 }
 
 export interface AppConfig {

packages/core/src/http-handler.ts

@@ -35,11 +35,12 @@ export class HttpHandler {
     this._bindFindRoute(requestContext);
     this._bindInvokeMethod(requestContext);
 
+    // TODO(bajtos) instantiate the Sequence via ctx.get()
     const findRoute = await requestContext.get('findRoute');
     const invokeMethod = await requestContext.get('invokeMethod');
+    const logError = await requestContext.get('logError');
+    const sequence = new Sequence(findRoute, invokeMethod, logError);
 
-    // TODO(bajtos) instantiate the Sequence via ctx.get()
-    const sequence = new Sequence(findRoute, invokeMethod, this.logError.bind(this));
     return sequence.run(parsedRequest, response);
   }
 
@@ -79,9 +80,4 @@ export class HttpHandler {
       };
     });
   }
-
-  logError(err: Error, statusCode: number, req: ServerRequest): void {
-    console.error('Unhandled error in %s %s: %s %s',
-      req.method, req.url, statusCode, err.stack || err);
-  }
 }

packages/core/test/integration/http-handler.integration.ts

@@ -3,7 +3,7 @@
 // This file is licensed under the MIT License.
 // License text available at https://opensource.org/licenses/MIT
 
-import {HttpHandler, Sequence} from '../..';
+import {HttpHandler, Sequence, ServerRequest} from '../..';
 import {Context} from '@loopback/context';
 import {expect, Client, createClientForHandler} from '@loopback/testlab';
 import {OpenApiSpec, ParameterObject} from '@loopback/openapi-spec';
@@ -374,6 +374,12 @@ context('with an operation echoing a string parameter from query', () => {
   let handler: HttpHandler;
   function givenHandler() {
     rootContext = new Context();
+    rootContext.bind('logError').to(logger);
+    function logger(err: Error, statusCode: number, req: ServerRequest) {
+      console.error('Unhandled error in %s %s: %s %s',
+        req.method, req.url, statusCode, err.stack || err);
+    }
+
     handler = new HttpHandler(rootContext);
   }
 
@@ -388,12 +394,13 @@ context('with an operation echoing a string parameter from query', () => {
   }
 
   function logErrorsExcept(ignoreStatusCode: number) {
-    // TODO(bajtos) Rework this code to customize the logger via rootContext.bind()
-    const oldLogger = handler.logError;
-    handler.logError = (err, statusCode, req) => {
+    const oldLogger: Function = rootContext.getSync('logError');
+    rootContext.bind('logError').to(conditionalLogger);
+
+    function conditionalLogger(err: Error, statusCode: number, req: ServerRequest) {
       if (statusCode === ignoreStatusCode) return;
       // tslint:disable-next-line:no-invalid-this
       oldLogger.apply(this, arguments);
-    };
+    }
   }
 });

packages/core/test/unit/application/application.test.ts

@@ -0,0 +1,34 @@
+// Copyright IBM Corp. 2013,2017. All Rights Reserved.
+// Node module: @loopback/core
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+import {expect, ShotRequest} from '@loopback/testlab';
+import {Application, ServerRequest} from '../../..';
+
+describe('Application', () => {
+  describe('"logError" binding', () => {
+    it('provides a default', async () => {
+      const app = new Application();
+      const logError = await app.get('logError');
+      expect(logError.length).to.equal(3); // (err, statusCode, request)
+    });
+
+    it('can be customized by overriding Application._logError() method', async () => {
+      let lastLog: string = 'logError() was not called';
+
+      class MyApp extends Application {
+        protected _logError(err: Error, statusCode: number, request: ServerRequest) {
+          lastLog = `${request.url} ${statusCode} ${err.message}`;
+        }
+      }
+
+      const app = new MyApp();
+      const logError = await app.get('logError');
+      logError(new Error('test-error'), 400, new ShotRequest({url: '/'}));
+
+      expect(lastLog).to.equal('/ 400 test-error');
+    });
+  });
+});
+