fix(rest): use strong-error-handler for writing errors to the respons…

…e body

packages/rest/package.json

@@ -41,6 +41,7 @@
     "lodash": "^4.17.5",
     "openapi-schema-to-json-schema": "^2.1.0",
     "path-to-regexp": "^2.2.0",
+    "strong-error-handler": "^3.2.0",
     "validator": "^10.4.0"
   },
   "devDependencies": {

packages/rest/src/keys.ts

@@ -24,6 +24,7 @@ import {
 
 import {HttpProtocol} from '@loopback/http-server';
 import * as https from 'https';
+import {ErrorWriterOptions} from 'strong-error-handler';
 
 /**
  * RestServer-specific bindings
@@ -59,6 +60,13 @@ export namespace RestBindings {
    * Internal binding key for http-handler
    */
   export const HANDLER = BindingKey.create<HttpHandler>('rest.handler');
+  /**
+   * Binding key for setting and injecting Reject action's error handling
+   * options
+   */
+  export const ERROR_WRITER_OPTIONS = BindingKey.create<ErrorWriterOptions>(
+    'rest.errorWriterOptions',
+  );
 
   /**
    * Binding key for setting and injecting an OpenAPI spec

packages/rest/src/providers/reject.provider.ts

@@ -6,15 +6,15 @@
 import {LogError, Reject, HandlerContext} from '../types';
 import {inject, Provider} from '@loopback/context';
 import {HttpError} from 'http-errors';
-import {writeErrorToResponse} from '../writer';
 import {RestBindings} from '../keys';
-
-const debug = require('debug')('loopback:rest:reject');
+import {writeErrorToResponse, ErrorWriterOptions} from 'strong-error-handler';
 
 export class RejectProvider implements Provider<Reject> {
   constructor(
     @inject(RestBindings.SequenceActions.LOG_ERROR)
     protected logError: LogError,
+    @inject(RestBindings.ERROR_WRITER_OPTIONS, {optional: true})
+    protected errorWriterOptions?: ErrorWriterOptions,
   ) {}
 
   value(): Reject {
@@ -24,17 +24,7 @@ export class RejectProvider implements Provider<Reject> {
   action({request, response}: HandlerContext, error: Error) {
     const err = <HttpError>error;
     const statusCode = err.statusCode || err.status || 500;
-    writeErrorToResponse(response, err);
-
-    // Always log the error in debug mode, even when the application
-    // has a custom error logger configured (e.g. in tests)
-    debug(
-      'HTTP request %s %s was rejected: %s %s',
-      request.method,
-      request.url,
-      statusCode,
-      err.stack || err,
-    );
+    writeErrorToResponse(err, request, response, this.errorWriterOptions);
     this.logError(error, statusCode, request);
   }
 }

packages/rest/src/writer.ts

@@ -4,7 +4,6 @@
 // License text available at https://opensource.org/licenses/MIT
 
 import {OperationRetval, Response} from './types';
-import {HttpError} from 'http-errors';
 import {Readable} from 'stream';
 
 /**
@@ -51,39 +50,3 @@ export function writeResultToResponse(
   }
   response.end();
 }
-
-/**
- * Write an error into the HTTP response
- * @param response HTTP response
- * @param error Error
- */
-export function writeErrorToResponse(response: Response, error: Error) {
-  const e = <HttpError>error;
-  const statusCode = (response.statusCode = e.statusCode || e.status || 500);
-  if (e.headers) {
-    // Set response headers for the error
-    for (const h in e.headers) {
-      response.setHeader(h, e.headers[h]);
-    }
-  }
-  // Build an error object
-  const errObj: Partial<HttpError> = {
-    statusCode,
-  };
-  if (e.expose) {
-    // Expose other properties if the `expose` flag is set to `true`
-    for (const p in e) {
-      if (
-        p === 'headers' ||
-        p === 'expose' ||
-        p === 'status' ||
-        p === 'statusCode'
-      )
-        continue;
-      errObj[p] = e[p];
-    }
-  }
-  response.setHeader('Content-Type', 'application/json');
-  response.write(JSON.stringify(errObj));
-  response.end();
-}

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

@@ -15,7 +15,7 @@ import {
 } from '../..';
 import {ControllerSpec, get} from '@loopback/openapi-v3';
 import {Context} from '@loopback/context';
-import {Client, createClientForHandler} from '@loopback/testlab';
+import {Client, createClientForHandler, expect} from '@loopback/testlab';
 import * as HttpErrors from 'http-errors';
 import {ParameterObject, RequestBodyObject} from '@loopback/openapi-v3-types';
 import {anOpenApiSpec, anOperationSpec} from '@loopback/openapi-spec-builder';
@@ -248,9 +248,12 @@ describe('HttpHandler', () => {
         .post('/show-body')
         .send('key=value')
         .expect(415, {
-          message:
-            'Content-type application/x-www-form-urlencoded is not supported.',
-          statusCode: 415,
+          error: {
+            message:
+              'Content-type application/x-www-form-urlencoded is not supported.',
+            name: 'UnsupportedMediaTypeError',
+            statusCode: 415,
+          },
         });
     });
 
@@ -260,7 +263,13 @@ describe('HttpHandler', () => {
         .post('/show-body')
         .set('content-type', 'application/json')
         .send('malformed-json')
-        .expect(400, {statusCode: 400});
+        .expect(400, {
+          error: {
+            message: 'Unexpected token m in JSON at position 0',
+            name: 'SyntaxError',
+            statusCode: 400,
+          },
+        });
     });
 
     function givenBodyParamController() {
@@ -329,7 +338,7 @@ describe('HttpHandler', () => {
   });
 
   context('error handling', () => {
-    it('handles errors throws by controller constructor', () => {
+    it('handles errors thrown by controller constructor', () => {
       const spec = anOpenApiSpec()
         .withOperationReturningString('get', '/hello', 'greet')
         .build();
@@ -344,7 +353,10 @@ describe('HttpHandler', () => {
 
       logErrorsExcept(500);
       return client.get('/hello').expect(500, {
-        statusCode: 500,
+        error: {
+          message: 'Internal Server Error',
+          statusCode: 500,
+        },
       });
     });
 
@@ -363,8 +375,11 @@ describe('HttpHandler', () => {
       logErrorsExcept(404);
 
       await client.get('/hello').expect(404, {
-        message: 'Controller method not found: TestController.unknownMethod',
-        statusCode: 404,
+        error: {
+          message: 'Controller method not found: TestController.unknownMethod',
+          name: 'NotFoundError',
+          statusCode: 404,
+        },
       });
     });
 
@@ -380,22 +395,20 @@ describe('HttpHandler', () => {
       class TestController {
         @get('/hello')
         hello() {
-          const err = new HttpErrors.BadRequest('Bad hello');
-          err.headers = {'X-BAD-REQ': 'hello'};
-          throw err;
+          throw new HttpErrors.BadRequest('Bad hello');
         }
       }
 
       givenControllerClass(TestController, spec);
       logErrorsExcept(400);
 
-      await client
-        .get('/hello')
-        .expect('X-BAD-REQ', 'hello')
-        .expect(400, {
+      await client.get('/hello').expect(400, {
+        error: {
           message: 'Bad hello',
+          name: 'BadRequestError',
           statusCode: 400,
-        });
+        },
+      });
     });
 
     it('handles 500 error thrown from the method', async () => {
@@ -418,6 +431,37 @@ describe('HttpHandler', () => {
       logErrorsExcept(500);
 
       await client.get('/hello').expect(500, {
+        error: {
+          message: 'Internal Server Error',
+          statusCode: 500,
+        },
+      });
+    });
+
+    it('respects error handler options', async () => {
+      rootContext.bind(RestBindings.ERROR_WRITER_OPTIONS).to({debug: true});
+
+      const spec = anOpenApiSpec()
+        .withOperation(
+          'get',
+          '/hello',
+          anOperationSpec().withOperationName('hello'),
+        )
+        .build();
+
+      class TestController {
+        @get('/hello')
+        hello() {
+          throw new HttpErrors.InternalServerError('Bad hello');
+        }
+      }
+
+      givenControllerClass(TestController, spec);
+      logErrorsExcept(500);
+
+      const response = await client.get('/hello').expect(500);
+      expect(response.body.error).to.containDeep({
+        message: 'Bad hello',
         statusCode: 500,
       });
     });