Merge pull request #15 from strongloop/html-response

Html response and content negotiation

README.md

@@ -8,10 +8,6 @@ Error handler for use in development (debug) and production environments.
  - When in debug mode, detailed information such as stack traces
    are returned in the HTTP responses.
 
-JSON is the only supported response format at this time.
-
-*There are plans to support other formats such as Text, HTML, and XML.*
-
 ## Install
 
 ```bash
@@ -47,6 +43,15 @@ In LoopBack applications, add the following entry to your
 }
 ```
 
+## Content Type
+
+Depending on the request header's `Accepts`, response will be returned in
+ the corresponding content-type, current supported types include:
+- JSON (`json`/`application/json`)
+- HTML (`html`/`text/html`)
+
+*There are plans to support other formats such as Text and XML.*
+
 ## Options
 
 #### debug

lib/content-negotiation.js

@@ -0,0 +1,85 @@
+// Copyright IBM Corp. 2016. All Rights Reserved.
+// Node module: strong-error-handler
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+var accepts = require('accepts');
+var debug = require('debug')('strong-error-handler:http-response');
+var sendJson = require('./send-json');
+var sendHtml = require('./send-html');
+var util = require('util');
+
+module.exports = negotiateContentProducer;
+
+/**
+ * Handles req.accepts and req.query._format and options.defaultType
+ * to resolve the correct operation
+ *
+ * @param req request object
+ * @param {Object} options options of strong-error-handler
+ * @returns {Function} Opeartion function with signature `fn(res, data)`
+ */
+function negotiateContentProducer(req, options) {
+  var SUPPORTED_TYPES = [
+    'application/json', 'json',
+    'text/html', 'html',
+  ];
+
+  options = options || {};
+  var defaultType = 'json';
+
+  // checking if user provided defaultType is supported
+  if (options.defaultType) {
+    if (SUPPORTED_TYPES.indexOf(options.defaultType) > -1) {
+      debug('Accepting options.defaultType `%s`', options.defaultType);
+      defaultType = options.defaultType;
+    } else {
+      debug('defaultType: `%s` is not supported, ' +
+        'falling back to defaultType: `%s`', options.defaultType, defaultType);
+    }
+  }
+
+  // decide to use resolvedType or defaultType
+  // Please note that accepts assumes the order of content-type is provided
+  // in the priority returned
+  // example
+  // Accepts: text/html, */*, application/json ---> will resolve as text/html
+  // Accepts: application/json, */*, text/html ---> will resolve as application/json
+  // Accepts: */*, application/json, text/html ---> will resolve as application/json
+  // eg. Chrome accepts defaults to `text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*`
+  // In this case `resolvedContentType` will result as: `text/html` due to the order given
+  var resolvedContentType = accepts(req).types(SUPPORTED_TYPES);
+  debug('Resolved content-type', resolvedContentType);
+  var contentType = resolvedContentType || defaultType;
+
+  // to receive _format from user's url param to overide the content type
+  // req.query (eg /api/Users/1?_format=json will overide content negotiation
+  // https://github.com/strongloop/strong-remoting/blob/ac3093dcfbb787977ca0229b0f672703859e52e1/lib/http-context.js#L643-L645
+  var query = req.query || {};
+  if (query._format) {
+    if (SUPPORTED_TYPES.indexOf(query._format) > -1) {
+      contentType = query._format;
+    } else {
+      // format passed through query but not supported
+      var msg = util.format('Response _format "%s" is not supported' +
+        'used "%s" instead"', query._format, defaultType);
+      res.header('X-Warning', msg);
+      debug(msg);
+    }
+  }
+
+  debug('Content-negotiation: req.headers.accept: `%s` Resolved as: `%s`',
+    req.headers.accept, contentType);
+  return resolveOperation(contentType);
+}
+
+function resolveOperation(contentType) {
+  switch (contentType) {
+    case 'application/json':
+    case 'json':
+      return sendJson;
+    case 'text/html':
+    case 'html':
+      return sendHtml;
+  }
+}

lib/handler.js

@@ -9,7 +9,7 @@ var buildResponseData = require('./data-builder');
 var debug = require('debug')('strong-error-handler');
 var format = require('util').format;
 var logToConsole = require('./logger');
-var sendJson = require('./send-json');
+var negotiateContentProducer = require('./content-negotiation');
 
 function noop() {
 }
@@ -52,11 +52,7 @@ exports = module.exports = function createStrongErrorHandler(options) {
     res.setHeader('X-Content-Type-Options', 'nosniff');
     res.statusCode = data.statusCode;
 
-    // TODO: negotiate the content-type, take into account options.defaultType
+    var sendResponse = negotiateContentProducer(req, options);
-    // For now, we always return JSON. See
+    sendResponse(res, data);
-    //  - https://github.com/strongloop/strong-error-handler/issues/4
-    //  - https://github.com/strongloop/strong-error-handler/issues/5
-    //  - https://github.com/strongloop/strong-error-handler/issues/6
-    sendJson(res, data);
   };
 };

lib/send-html.js

@@ -0,0 +1,46 @@
+// Copyright IBM Corp. 2016. All Rights Reserved.
+// Node module: strong-error-handler
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+var ejs = require('ejs');
+var fs = require('fs');
+var path = require('path');
+
+var assetDir = path.resolve(__dirname, '../views');
+var compiledTemplates = {
+  // loading default template and stylesheet
+  default: loadDefaultTemplates(),
+};
+
+module.exports = sendHtml;
+
+function sendHtml(res, data, options) {
+  var toRender = {options: {}, data: data};
+  // TODO: ability to call non-default template functions from options
+  var body = compiledTemplates.default(toRender);
+  sendReponse(res, body);
+}
+
+/**
+ * Compile and cache the file with the `filename` key in options
+ *
+ * @param filepath (description)
+ * @returns {Function} render function with signature fn(data);
+ */
+function compileTemplate(filepath) {
+  var options = {cache: true, filename: filepath};
+  fileContent = fs.readFileSync(filepath, 'utf8');
+  return ejs.compile(fileContent, options);
+}
+
+// loads and cache default error templates
+function loadDefaultTemplates() {
+  var defaultTemplate = path.resolve(assetDir, 'default-error.ejs');
+  return compileTemplate(defaultTemplate);
+}
+
+function sendReponse(res, body) {
+  res.setHeader('Content-Type', 'text/html; charset=utf-8');
+  res.end(body);
+}

package.json

@@ -14,14 +14,20 @@
     "posttest": "npm run lint"
   },
   "dependencies": {
+    "accepts": "^1.3.3",
     "debug": "^2.2.0",
+    "ejs": "^2.4.2",
     "http-status": "^0.2.2"
   },
   "devDependencies": {
     "chai": "^2.1.1",
     "eslint": "^2.5.3",
     "eslint-config-loopback": "^3.0.0",
+    "express": "^4.13.4",
     "mocha": "^2.1.0",
     "supertest": "^1.1.0"
+  },
+  "browser": {
+    "strong-error-handler": false
   }
 }

test/handler.test.js

@@ -8,7 +8,7 @@
 var cloneAllProperties = require('../lib/clone.js');
 var debug = require('debug')('test');
 var expect = require('chai').expect;
-var http = require('http');
+var express = require('express');
 var strongErrorHandler = require('..');
 var supertest = require('supertest');
 var util = require('util');
@@ -361,9 +361,156 @@ describe('strong-error-handler', function() {
         .expect('Content-Type', /^application\/json/);
     }
   });
+
+  context('HTML response', function() {
+    it('contains all error properties when debug=true', function(done) {
+      var error = new ErrorWithProps({
+        message: 'a test error message',
+        details: 'some details',
+        extra: 'sensitive data',
+      });
+      error.statusCode = 500;
+      givenErrorHandlerForError(error, {debug: true});
+      requestHTML()
+        .expect(500)
+        .expect(/<title>ErrorWithProps<\/title>/)
+        .expect(/500(.*?)a test error message/)
+        .expect(/extra(.*?)sensitive data/)
+        .expect(/details(.*?)some details/)
+        .expect(/id="stacktrace"(.*?)ErrorWithProps: a test error message/,
+          done);
+    });
+
+    it('contains subset of properties when status=4xx', function(done) {
+      var error = new ErrorWithProps({
+        name: 'ValidationError',
+        message: 'The model instance is not valid.',
+        statusCode: 422,
+        details: 'some details',
+        extra: 'sensitive data',
+      });
+      givenErrorHandlerForError(error, {debug: false});
+      requestHTML()
+        .end(function(err, res) {
+          expect(res.statusCode).to.eql(422);
+          var body = res.error.text;
+          expect(body).to.match(/some details/);
+          expect(body).to.not.match(/sensitive data/);
+          expect(body).to.match(/<title>ValidationError<\/title>/);
+          expect(body).to.match(/422(.*?)The model instance is not valid./);
+          done();
+        });
+    });
+
+    it('contains only safe info when status=5xx', function(done) {
+      // Mock an error reported by fs.readFile
+      var error = new ErrorWithProps({
+        name: 'Error',
+        message: 'ENOENT: no such file or directory, open "/etc/passwd"',
+        errno: -2,
+        code: 'ENOENT',
+        syscall: 'open',
+        path: '/etc/password',
+      });
+      givenErrorHandlerForError(error);
+
+      requestHTML()
+        .end(function(err, res) {
+          expect(res.statusCode).to.eql(500);
+          var body = res.error.text;
+          expect(body).to.not.match(/\/etc\/password/);
+          expect(body).to.not.match(/-2/);
+          expect(body).to.not.match(/ENOENT/);
+          // only have the following
+          expect(body).to.match(/<title>Internal Server Error<\/title>/);
+          expect(body).to.match(/500(.*?)Internal Server Error/);
+          done();
+        });
+    });
+
+    function requestHTML(url) {
+      return request.get(url || '/')
+        .set('Accept', 'text/html')
+        .expect('Content-Type', /^text\/html/);
+    }
+  });
+
+  context('Content Negotiation', function() {
+    it('defaults to json without options', function(done) {
+      givenErrorHandlerForError(new Error('Some error'), {});
+      request.get('/')
+        .set('Accept', '*/*')
+        .expect('Content-Type', /^application\/json/, done);
+    });
+
+    it('honors accepted content-type', function(done) {
+      givenErrorHandlerForError(new Error('Some error'), {
+        defaultType: 'application/json',
+      });
+      request.get('/')
+        .set('Accept', 'text/html')
+        .expect('Content-Type', /^text\/html/, done);
+    });
+
+    it('honors order of accepted content-type', function(done) {
+      givenErrorHandlerForError(new Error('Some error'), {
+        defaultType: 'text/html',
+      });
+      request.get('/')
+        // `application/json` will be used because its provided first
+        .set('Accept', 'application/json, text/html')
+        .expect('Content-Type', /^application\/json/, done);
+    });
+
+    it('honors order of accepted content-types of text/html', function(done) {
+      givenErrorHandlerForError(new Error('Some error'), {
+        defaultType: 'application/json',
+      });
+      request.get('/')
+        // text/html will be used because its provided first
+        .set('Accept', 'text/html, application/json')
+        .expect('Content-Type', /^text\/html/, done);
+    });
+
+    it('picks first supported type upon multiple accepted', function(done) {
+      givenErrorHandlerForError(new Error('Some error'), {
+        defaultType: 'application/json',
+      });
+      request.get('/')
+        .set('Accept', '*/*, not-supported, text/html, application/json')
+        .expect('Content-Type', /^text\/html/, done);
+    });
+
+    it('falls back for unsupported option.defaultType', function(done) {
+      givenErrorHandlerForError(new Error('Some error'), {
+        defaultType: 'unsupported',
+      });
+      request.get('/')
+        .set('Accept', '*/*')
+        .expect('Content-Type', /^application\/json/, done);
+    });
+
+    it('returns defaultType for unsupported type', function(done) {
+      givenErrorHandlerForError(new Error('Some error'), {
+        defaultType: 'text/html',
+      });
+      request.get('/')
+        .set('Accept', 'unsupported/type')
+        .expect('Content-Type', /^text\/html/, done);
+    });
+
+    it('supports query _format', function(done) {
+      givenErrorHandlerForError(new Error('Some error'), {
+        defaultType: 'text/html',
+      });
+      request.get('/?_format=html')
+        .set('Accept', 'application/json')
+        .expect('Content-Type', /^text\/html/, done);
+    });
+  });
 });
 
-var _httpServer, _requestHandler, request;
+var app, _requestHandler, request;
 function resetRequestHandler() {
   _requestHandler = null;
 }
@@ -387,7 +534,8 @@ function givenErrorHandlerForError(error, options) {
 }
 
 function setupHttpServerAndClient(done) {
-  _httpServer = http.createServer(function(req, res) {
+  app = express();
+  app.use(function(req, res, next) {
     if (!_requestHandler) {
       var msg = 'Error handler middleware was not setup in this test';
       console.error(msg);
@@ -396,8 +544,22 @@ function setupHttpServerAndClient(done) {
       res.end(msg);
       return;
     }
+    _requestHandler(req, res, warnUnhandledError);
+  });
 
-    _requestHandler(req, res, function(err) {
+  app.listen(0, function() {
+    var url = 'http://127.0.0.1:' + this.address().port;
+    debug('Test server listening on %s', url);
+    request = supertest(app);
+    done();
+  })
+  .once('error', function(err) {
+    debug('Cannot setup HTTP server: %s', err.stack);
+    done(err);
+  });
+}
+
+function warnUnhandledError(err) {
   console.log('unexpected: strong-error-handler called next with '
     (err && (err.stack || err)) || 'no error');
   res.statusCode = 500;
@@ -405,22 +567,6 @@ function setupHttpServerAndClient(done) {
   res.end(err ?
     'Unhandled strong-error-handler error:\n' + (err.stack || err) :
     'The error was silently discared by strong-error-handler');
-    });
-  });
-
-  _httpServer.once('error', function(err) {
-    debug('Cannot setup HTTP server: %s', err.stack);
-    done(err);
-  });
-
-  _httpServer.once('listening', function() {
-    var url = 'http://127.0.0.1:' + this.address().port;
-    debug('Test server listening on %s', url);
-    request = supertest(url);
-    done();
-  });
-
-  _httpServer.listen(0, '127.0.0.1');
 }
 
 function ErrorWithProps(props) {

views/default-error.ejs

@@ -0,0 +1,25 @@
+<html>
+  <head>
+    <meta charset='utf-8'>
+    <title><%- data.name || data.message %></title>
+    <style><%- include style.css %></style>
+  </head>
+  <body>
+    <div id="wrapper">
+      <h1><%- data.name %></h1>
+      <h2><em><%- data.statusCode %></em> <%- data.message %></h2>
+      <%
+        // display all the non-standard properties
+        var standardProps = ['name', 'statusCode', 'message', 'stack'];
+        for (var prop in data) {
+          if (standardProps.indexOf(prop) == -1 && data[prop]) { %>
+            <div><b><%- prop %></b>: <%- data[prop] %></div>
+          <% }
+        }
+        if (data.stack) { %>
+          <pre id="stacktrace"><%- data.stack %></pre>
+        <% }
+      %>
+    </div>
+  </body>
+</html>

views/style.css

@@ -0,0 +1,31 @@
+* {
+  margin: 0;
+  padding: 0;
+  outline: 0;
+}
+body {
+  padding: 80px 100px;
+  font: 13px "Helvetica Neue", "Lucida Grande", "Arial";
+  background: #ECE9E9 -webkit-gradient(linear, 0% 0%, 0% 100%, from(#fff), to(#ECE9E9));
+  background: #ECE9E9 -moz-linear-gradient(top, #fff, #ECE9E9);
+  background-repeat: no-repeat;
+  color: #555;
+  -webkit-font-smoothing: antialiased;
+}
+h1, h2 {
+  font-size: 22px;
+  color: #343434;
+}
+h1 em, h2 em {
+  padding: 0 5px;
+  font-weight: normal;
+}
+h1 {
+  font-size: 60px;
+}
+h2 {
+  margin: 10px 0;
+}
+ul li {
+  list-style: none;
+}